Subjects -> CHEMISTRY (Total: 928 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (661 journals)
    - CRYSTALLOGRAPHY (23 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
    - ORGANIC CHEMISTRY (47 journals)
    - PHYSICAL CHEMISTRY (65 journals)

CHEMISTRY (661 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accounts of Materials Research     Hybrid Journal   (Followers: 11)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 33)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 18)
ACS Catalysis     Hybrid Journal   (Followers: 61)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 26)
ACS Combinatorial Science     Hybrid Journal   (Followers: 14)
ACS Environmental Au     Open Access   (Followers: 11)
ACS Macro Letters     Hybrid Journal   (Followers: 29)
ACS Materials Letters     Open Access   (Followers: 10)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 45)
ACS Nano     Hybrid Journal   (Followers: 235)
ACS Photonics     Hybrid Journal   (Followers: 16)
ACS Symposium Series     Full-text available via subscription   (Followers: 5)
ACS Synthetic Biology     Hybrid Journal   (Followers: 39)
Acta Chemica Malaysia     Open Access   (Followers: 2)
Acta Chimica Slovaca     Open Access   (Followers: 4)
Acta Chimica Slovenica     Open Access   (Followers: 4)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 10)
Acta Scientifica Naturalis     Open Access   (Followers: 4)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 10)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 12)
Adsorption Science & Technology     Open Access   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 14)
Advanced Functional Materials     Hybrid Journal   (Followers: 78)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 4)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 3)
Advanced Science Focus     Free   (Followers: 8)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 141)
Advances in Chemical Science     Open Access   (Followers: 52)
Advances in Chemistry     Open Access   (Followers: 40)
Advances in Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Environmental Chemistry     Open Access   (Followers: 15)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 35)
Advances in Nanoparticles     Open Access   (Followers: 17)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Polymer Science     Hybrid Journal   (Followers: 50)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Sample Preparation     Open Access   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 18)
Aerosol Science and Engineering     Hybrid Journal   (Followers: 2)
African Journal of Chemical Education     Open Access   (Followers: 7)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Aggregate     Open Access   (Followers: 2)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 2)
Alchemy : Jurnal Penelitian Kimia     Open Access  
Alfarama Journal of Basic & Applied Sciences     Open Access   (Followers: 12)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 45)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 21)
American Journal of Chemistry     Open Access   (Followers: 37)
American Journal of Plant Physiology     Open Access   (Followers: 9)
Analyst     Hybrid Journal   (Followers: 35)
Analytical Science Advances     Open Access   (Followers: 1)
Angewandte Chemie     Hybrid Journal   (Followers: 173)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 285)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 6)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 5)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 14)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 20)
Applied Surface Science     Hybrid Journal   (Followers: 31)
Arabian Journal of Chemistry     Open Access   (Followers: 4)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 2)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 2)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 8)
Autophagy     Hybrid Journal   (Followers: 8)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Hybrid Journal   (Followers: 257)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 5)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 24)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 3)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 86)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 61)
Bioorganic Chemistry     Hybrid Journal   (Followers: 7)
Biopolymers     Hybrid Journal   (Followers: 15)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 3)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 25)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 5)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 1)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 11)
Canadian Mineralogist     Full-text available via subscription   (Followers: 5)
Carbohydrate Polymer Technologies and Applications     Open Access   (Followers: 1)
Carbohydrate Polymers     Hybrid Journal   (Followers: 11)
Carbohydrate Research     Hybrid Journal   (Followers: 23)
Carbon     Hybrid Journal   (Followers: 64)
Carbon Capture Science & Technology     Open Access   (Followers: 1)
Carbon Trends     Open Access   (Followers: 6)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 10)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 12)
Cell Reports Physical Science     Open Access   (Followers: 1)
Cellulose     Hybrid Journal   (Followers: 8)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
Chem     Hybrid Journal   (Followers: 8)
Chem Catalysis     Hybrid Journal   (Followers: 2)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 22)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Hybrid Journal   (Followers: 85)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Physics Impact     Full-text available via subscription   (Followers: 1)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 228)
Chemical Science     Open Access   (Followers: 45)
Chemical Science International Journal     Open Access  
Chemical Technology     Open Access   (Followers: 75)
Chemical Thermodynamics and Thermal Analysis     Open Access   (Followers: 4)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 39)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 18)
ChemInform     Hybrid Journal   (Followers: 5)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Industry     Full-text available via subscription   (Followers: 6)
Chemistry - A European Journal     Hybrid Journal   (Followers: 154)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 22)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 7)
Chemistry Education Review     Open Access   (Followers: 2)
Chemistry in Education     Open Access   (Followers: 5)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 5)
Chemistry of Materials     Hybrid Journal   (Followers: 195)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Hybrid Journal   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal   (Followers: 1)
Chemistry–Methods     Open Access   (Followers: 4)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 13)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPhysMater     Full-text available via subscription  
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access  
ChemSystemsChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal   (Followers: 1)
CHIMIA International Journal for Chemistry     Open Access   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 9)
Chromatographia     Hybrid Journal   (Followers: 21)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 4)
Ciencia     Open Access  
Clay Minerals     Hybrid Journal   (Followers: 9)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 7)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 9)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 2)
Combustion Science and Technology     Hybrid Journal   (Followers: 26)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Communications Chemistry     Open Access   (Followers: 2)
Communications Materials     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 7)

        1 2 3 4 | Last

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ISSN (Online) 2624-8549
Published by MDPI Homepage  [258 journals]
  • Chemistry, Vol. 5, Pages 2056-2067: Direct Aniline Formation with Benzene
           and Hydroxylamine

    • Authors: Ningyu Liu, Matthew D. Sleck, William D. Jones
      First page: 2056
      Abstract: A single-step method for aniline formation was examined. Using a vanadate catalyst with an iron oxide co-catalyst and hydroxylamine hydrochloride as the amine source, an up to 90% yield of aniline was obtained with high selectivity. Further study showed that the overall reaction was pseudo-second order in terms of hydroxylamine concentration. Regioselective H-D exchange experiments suggest that the C-N bond formation step occurs via an irreversible electrophilic pathway. Based on all of the key observations, a mechanism is proposed.
      Citation: Chemistry
      PubDate: 2023-09-23
      DOI: 10.3390/chemistry5040139
      Issue No: Vol. 5, No. 4 (2023)
  • Chemistry, Vol. 5, Pages 2068-2074: Isoselenazole Synthesis by
           Rh-Catalyzed Direct Annulation of Benzimidates with Sodium Selenite

    • Authors: Qing-Feng Xu-Xu, Yuji Nishii, Masahiro Miura
      First page: 2068
      Abstract: Organoselenium compounds have attracted significant research interest because of their potent therapeutic activities and indispensable applications in the organic chemistry field. The selenation reactions conventionally rely on the use of sensitive Se reagents; thus, new synthetic methods with improved efficiency and operational simplicity have recently been of particular interest. In this manuscript, we report a Rh-catalyzed direct selenium annulation using tractable sodium selenite (Na2SeO3) as the limiting reagent. The selenite species was converted to highly electrophilic SeO(OBz)2 in situ upon treatment with Bz2O, thereby undergoing C–H/N–H double nucleophilic selenation. A series of benzimidates successfully underwent selenation under mild reaction conditions to afford isoselenazole derivatives.
      Citation: Chemistry
      PubDate: 2023-09-23
      DOI: 10.3390/chemistry5040140
      Issue No: Vol. 5, No. 4 (2023)
  • Chemistry, Vol. 5, Pages 1477-1487: Metal-Free Eliminative C-H
           Arylthiolation of 2H-Imidazole N-Oxides with Thiophenols

    • Authors: Egor A. Nikiforov, Nailya F. Vaskina, Timofey D. Moseev, Mikhail V. Varaksin, Valery N. Charushin, Oleg N. Chupakhin
      First page: 1477
      Abstract: A synthetic strategy based on reactions of cyclic imine oxides, namely 2H-imidazole 1-oxides, with thiophenols mediated by acetyl chloride was successfully applied as a convenient tool to obtain a series of novel azaheterocyclic molecules, including water-soluble hydrochloride forms. Optimized reaction conditions found herein for the nucleophilic substitution of hydrogen (SNH) in non-aromatic azaheterocyclic substrates via the “addition-elimination” (SNH AE) scheme enabled 15 arylthiolated 2H-imidazoles to be prepared in yields of up to 90%. The developed methodology discloses an original synthetic way to obtain numerous azaheterocyclic molecules, which are of interest in the field of medicinal chemistry and materials science.
      Citation: Chemistry
      PubDate: 2023-06-24
      DOI: 10.3390/chemistry5030100
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1488-1496: Synthesis of Selenium-Based Small
           Molecules Inspired by CNS-Targeting Psychotropic Drugs and Mediators

    • Authors: Giovanni Ribaudo, Davide Zeppilli, Alberto Ongaro, Marco Bortoli, Giuseppe Zagotto, Laura Orian
      First page: 1488
      Abstract: Due to its endogenously high oxygen consumption, the central nervous system (CNS) is vulnerable to oxidative stress conditions. Notably, the activity of several CNS-targeting compounds, such as antidepressant and hypnotic drugs, or endogenous mediators, such as melatonin, is indeed linked to their ability of mitigating oxidative stress. In this work, we report the synthesis of two organoselenium compounds of which the structure was inspired by CNS-targeting psychotropic drugs (zolpidem and fluoxetine) and an endogenous mediator (melatonin). The molecules were designed with the aim of combining the ROS-scavenging properties, which were already assessed for the parent compounds, with a secondary antioxidant action, a glutathione peroxidase (GPx) mimic role empowered by the presence of selenium. The compounds were obtained through a facile three-step synthesis and were predicted by computational tools to passively permeate through the blood–brain barrier and to efficiently bind to the GABA A receptor, the macromolecular target of zolpidem. Of note, the designed synthetic pathway enables the production of several other derivatives through minor modifications of the scheme, paving the way for structure–activity relationship studies.
      Citation: Chemistry
      PubDate: 2023-06-27
      DOI: 10.3390/chemistry5030101
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1497-1507: Photocatalytic Duplex-Based DNAzymes
           Switched by an Abasic Site

    • Authors: Longlong Gao, Rui Tian, Yong Shao
      First page: 1497
      Abstract: DNAzymes have attracted increasing interest in developments of gene tools, therapies, and biosensors. Among them, G-quadruplexes are widely used as the key structure elements of DNAzymes to activate the catalytic competency of specific cofactors, such as hemin, but there is a great demand to diversify DNAzymes using other more straightforward DNA structures such as fully matched duplex (FM-DNA). However, the perfect base pairs in duplex limit the DNAzyme activity. In this work, a photocatalytic DNAzyme was developed by introducing an abasic site (AP site) into duplex (AP-DNA) to switch its photocatalytic activity. Palmatine (PAL), a photosensitizer from natural isoquinoline alkaloids, served as a cofactor of the DNAzyme by binding at the AP site. The AP site provides a less polarized environment to favor the PAL fluorescence. As a result, dissolved oxygen was converted into singlet oxygen (1O2) via energy transfer from the excited PAL. The oxidation of substrates by the in situ photogenerated 1O2 served as a readout for the DNAzyme. In addition, the duplex-based DNAzyme was engineered from FM-DNA by the cascade uracil-DNA glycosylase to generate AP-DNA. Our work provides a new way to construct duplex-based DNAzymes.
      Citation: Chemistry
      PubDate: 2023-06-28
      DOI: 10.3390/chemistry5030102
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1508-1517: Synthesis of the Bipyridine-Type
           Ligand 3-(2-Pyridyl)-5,6-diphenyl-1,2,4-triazine and Structural
           Elucidation of Its Cu(I) and Ag(I) Complexes

    • Authors: Antonios Hatzidimitriou, Antonios Stamatiou, Dimitrios Tzimopoulos, Pericles D. Akrivos
      First page: 1508
      Abstract: The synthesis of a substituted diimine with a bipydirine-type backbone, (3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine, L) and its coordination towards Cu(I) and Ag(I) is studied in the presence of diphosphine ligand bis(diphenylphosphino)methane, dppm. The metal complexes are characterized by IR, 1H, and 13C NMR and single crystal X ray diffraction studies. They are dinuclear, as they are held by diphosphine bridges between the tetrahedral metal centers, forming eight-membered ring with the participation of the bridging diphosphinomethane ligands. Within each ring, the planar orientations of M2P2 and of all four P atoms are realized. Solid state excitation spectra are dominated by metal-to-ligand charge transfer bands (MLCT), while geometry relaxation permits only low-intensity emission for the copper compound.
      Citation: Chemistry
      PubDate: 2023-07-05
      DOI: 10.3390/chemistry5030103
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1518-1534: Catalytic Performances of Co/TiO2
           Catalysts in the Oxidative Dehydrogenation of Ethane to Ethylene: Effect
           of CoTiO3 and Co2TiO4 Phase Formation

    • Authors: Hanane Mahir, Younes Brik, Abdallah Benzaouak, Eleonora La Greca, Luca Consentino, Mohamed Kacimi, Adnane El Hamidi, Leonarda Francesca Liotta
      First page: 1518
      Abstract: Co/TiO2 catalysts with different cobalt loadings (3.8, 7.5 and 15 wt%) were prepared by impregnation method of Co(NO3)2 6H2O over titania. Samples containing Co(NO3)2·6H2O and TiO2 in stoichiometric proportions in order to obtain CoTiO3 and Co2 TiO4 phases were also synthesized. The effect of the calcination treatment at two different temperatures, 550 and 1150 °C, was investigated. Characterizations by several techniques, such as XRD, UV–vis–NIR, DRS, Raman and XPS, were carried out. XRD showed the coexistence of three phases: CoTiO3; Co2TiO4 and Co3O4 after calcination at 550 °C, while calcination at high temperature (1150 °C) led to single-phase systems (CoTiO3 or Co2TiO4). Diffuse reflection and XPS spectroscopy showed that divalent cobalt occupies octahedral sites in the ilmenite phase, and both tetrahedral and octahedral sites in the spinel phase. The catalytic performances of the prepared catalysts were evaluated in the oxidative dehydrogenation reaction (ODH) of ethane to ethylene, as a function of the Co content for Co/TiO2 catalysts and as a function of the calcination temperatures for the CoTiO3 and Co2TiO4 phases. Co(7.5)/TiO2 was the most active, although the conversion of ethane decreased in the first 150 min of the reaction, reaching values comparable to those of Co2TiO4 and CoTiO3; however, Co(7.5)/TiO2 was confirmed as having the best selectivity to ethylene in comparison with the bulk phases, CoTiO3 and Co2TiO4. The influence of the reaction mixture composition, specifically the presence of water, at different percentages, was investigated. There is a decrease in the overall ethane conversion and an increase in the ethylene selectivity when the percentage of water increases. This behavior can likely be attributed to an increase in the surface concentration of hydroxyl species (OH), resulting in heightened surface acidity.
      Citation: Chemistry
      PubDate: 2023-07-06
      DOI: 10.3390/chemistry5030104
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1535-1545: Exploring the Potential Energy Surface
           of Medium-Sized Aromatic Polycyclic Systems with Embedded Planar
           Tetracoordinate Carbons: A Guided Approach

    • Authors: Diego Inostroza, Luis Leyva-Parra, Osvaldo Yañez, Andrew L. Cooksy, Venkatesan S. Thimmakondu, William Tiznado
      First page: 1535
      Abstract: This study scrutinizes the complexities of designing and exploring the potential energy surfaces of systems containing more than twenty atoms with planar tetracoordinate carbons (ptCs). To tackle this issue, we utilized an established design rule to design a Naphtho [1,2-b:3,4-b′:5,6-b″:7,8-b′′′]tetrathiophene derivative computationally. This process began with substituting S atoms with CH− units, then replacing three sequential protons with two Si2+ units in the resultant polycyclic aromatic hydrocarbon polyanion. Despite not representing the global minimum, the newly designed Si8C22 system with four ptCs provided valuable insights into strategic design and potential energy surface exploration. Our results underscore the importance of employing adequate methodologies to confirm the stability of newly designed molecular structures containing planar hypercoordinate carbons.
      Citation: Chemistry
      PubDate: 2023-07-11
      DOI: 10.3390/chemistry5030105
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1546-1559: DNA-Based Mechanical Sensors for Cell

    • Authors: Xiaoya Sun, Pengyan Hao, Na Wu
      First page: 1546
      Abstract: Cells constantly experience mechanical forces during growth and development. Increasing evidence suggests that mechanical forces can regulate cellular processes such as proliferation, migration, and differentiation. Therefore, developing new tools to measure and manipulate cellular mechanical forces is essential. DNA nanostructures, due to their simple design and high programmability, have been utilized to create various mechanical sensors and have become a key tool for studying mechanical information in both cellular and non-cellular systems. In this article, we review the development of DNA-based mechanical sensors and their applications in measuring mechanical forces in the extracellular matrix and cell–cell interactions and summarize the latest advances in monitoring and manipulating cellular morphology and function. We hope that this review can provide insights for the development of new mechanical nanodevices.
      Citation: Chemistry
      PubDate: 2023-07-19
      DOI: 10.3390/chemistry5030106
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1560-1576: Exploring the Effect of Sn Addition to
           Supported Au Nanoparticles on Reducible/Non-Reducible Metal Oxides
           Supports for Alkane Oxidation

    • Authors: Marta Stucchi, Alessandro Vomeri, Sándor Stichleutner, Károly Lázár, Emanuela Pitzalis, Claudio Evangelisti, Laura Prati
      First page: 1560
      Abstract: Acetone-stabilized Au- and Sn-solvated metal atoms (SMAs) were used as to obtain Au- and AuSn-supported catalysts by simple impregnation on a reducible (TiO2) and a non-reducible (Al2O3) metal-oxide. Their catalytic behaviour was investigated for cyclohexane oxidation to cyclohexanol and cyclohexanone (KA oil), and their morphological and physical properties were studied by TEM, STEM-EDS and 119Sn-Mössbauer spectroscopy. The catalytic results firstly demonstrated that the bare supports played a role on the reaction mechanism, slowing down the formation of the oxidation products and directing the radical formation. Hereinafter, the comparison between the monometallic Au-supported catalysts and the corresponding bimetallic Au-Sn catalysts allowed for the understanding of the potential role of Sn. 119Sn-Mössbauer characterization analyses showed the presence of SnO2, which was recognized to favour the electrons’ exchange to form radicals, interacting with oxygen. Such interaction, in particular, could be favoured by the co-presence of Au. Moreover, the same metal composition on the catalyst surface resulted in a different catalytic behaviour depending on the support.
      Citation: Chemistry
      PubDate: 2023-07-21
      DOI: 10.3390/chemistry5030107
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1577-1587: Coupling 2-Aminopurine with DNA Copper
           Nanoparticles as a Rapid and Enzyme-Free System for Operating DNA Contrary
           Logic Pairs

    • Authors: Jun Wang, Jiawen Han, Xujuan Lv, Jingyu Hou, Daoqing Fan, Shaojun Dong
      First page: 1577
      Abstract: Exploring affordable and efficient platform for innovative DNA computing is of great significance. Herein, by coupling 2-aminopurine (2AP) with DNA copper nanoparticles (CuNPs) as two universal opposite outputs, we, for the first time, fabricated a rapid and enzyme-free system for operating DNA contrary logic pairs (D-CLPs). Notably, derived from the rapid and concomitant response of both fluorescent probes, different D-CLPs can be achieved via a “double-results-half-efforts” manner in less than 20 min with low-cost. Moreover, based on the same system, the smart ratiometric analysis of target DNA was realized by employing the high reliability and accuracy of D-CLPs, providing a robust and typical paradigm for the exploration of smart nucleic acid sensors.
      Citation: Chemistry
      PubDate: 2023-07-23
      DOI: 10.3390/chemistry5030108
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1588-1598: Low-Temperature Properties of the
           Sodium-Ion Electrolytes Based on EC-DEC, EC-DMC, and EC-DME Binary

    • Authors: Denis S. Lutsenko, Ekaterina V. Belova, Maxim V. Zakharkin, Oleg A. Drozhzhin, Evgeny V. Antipov
      First page: 1588
      Abstract: Sodium-ion batteries are a promising class of secondary power sources that can replace some of the lithium-ion, lead–acid, and other types of batteries in large-scale applications. One of the critical parameters for their potential use is high efficiency in a wide temperature range, particularly below 0 °C. This article analyzes the phase equilibria and electrochemical properties of sodium-ion battery electrolytes that are based on NaPF6 solutions in solvent mixtures of ethylene carbonate and diethyl carbonate (EC:DEC), dimethyl carbonate (EC:DMC), and 1,2-dimethoxyethane (EC:DME). All studied electrolytes demonstrate a decrease in conductivity at lower temperatures and transition to a quasi-solid state resembling “wet snow” at certain temperatures: EC:DEC at −8 °C, EC:DMC at −13 °C, and EC:DME at −21 °C for 1 M NaPF6 solutions. This phase transition affects their conductivity to a different degree. The impact is minimal in the case of EC:DEC, although it partially freezes at a higher temperature than other electrolytes. The EC:DMC-based electrolyte demonstrates the best efficiency at temperatures down to −20 °C. However, upon further cooling, 1 M NaPF6 in EC:DEC retains a higher conductivity and lower resistivity in symmetrical Na3V2(PO4)3-based cells. The temperature range from −20 to −40 °C is characterized by the strongest deterioration in the electrochemical properties of electrolytes: for 1 M NaPF6 in EC:DMC, the charge transfer resistance increased 36 times, and for 1 M NaPF6 in EC:DME, 450 times. For 1 M NaPF6 in EC:DEC, the growth of this parameter is much more modest and amounts to only 1.7 times. This allows us to consider the EC:DEC-based electrolyte as a promising basis for the further development of low-temperature sodium-ion batteries.
      Citation: Chemistry
      PubDate: 2023-07-23
      DOI: 10.3390/chemistry5030109
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1599-1620: Structural and Magnetic Analysis of a
           Family of Structurally Related Iron(III)-Oxo Clusters of Metal Nuclearity
           Fe8, Fe12Ca4, and Fe12La4

    • Authors: Alok P. Singh, ChristiAnna L. Brantley, Kenneth Hong Kit Lee, Khalil A. Abboud, Juan E. Peralta, George Christou
      First page: 1599
      Abstract: The synthesis, crystal structure, and magnetic characterization are reported for three new structurally related iron(III) compounds (NHEt3)[Fe8O5(OH)5(O2PPh2)10] (1), [Fe12 Ca4O10(O2CPh)10(hmp)4] (2), and [Fe12La4O10(OH)4(tbb)24] (3), where hmpH is 2-(hydroxymethyl)pyridine and tbbH is 4-tBu-benzoic acid. 1 was obtained from the reaction of Fe(NO3)3·9H2O, diphenylphosphinic acid (Ph2PO2H), and NEt3 in a 1:4:16 molar ratio in MeCN at 50 °C; 2 was obtained from the reaction of [Fe3O(O2CPh)6(H2O)3](NO3), Ca(NO3)2, and NEt3 in a 1:1:4:2 ratio at 130 °C; and 3 was obtained from the reaction of Fe(NO3)3·9H2O, La(NO3)3·6H2O, 4-tBu-benzoic acid, and NEt3 in a 1:1:4:4 ratio in PhCN at 140 °C. The core of 1 consists of two {Fe4(µ3-O)2}8+ butterfly units stacked on top of each other and bridged by O2− and HO− ions. The cores of 2 and 3 also contain two stacked butterfly units, plus four additional Fe atoms, two at each end, and four M atoms (M = Ca2+ (2); La3+ (3)) on the sides. Variable-temperature (T) and solid-state dc and ac magnetization (M) data collected in the 1.8–300 K range revealed that 1 has an S = 0 ground state, 2 has a χMT value at low T consistent with the central Fe8 in a local S = 0 ground state and the two Fe3+ ions in each end-pair to be non-interacting, whereas 3 has a χMT value at low T consistent with these end-pairs each being ferromagnetically coupled with S = 5 ground states, plus intermolecular ferromagnetic interactions. These conclusions were reached from complementing the experimental studies with the calculation of the various Fe2 pairwise Jij exchange couplings by DFT computations and by using a magnetostructural correlation (MSC) for polynuclear Fe3+/O complexes, as well as a structural analysis of the intermolecular contacts in the crystal packing of 3.
      Citation: Chemistry
      PubDate: 2023-07-24
      DOI: 10.3390/chemistry5030110
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1621-1633: Constructing a Triangle Ensemble of Pt
           Clusters for Enhanced Direct-Pathway Electrocatalysis of Formic Acid

    • Authors: Cheng Li, Zheng Tang, Lanlan Shi, Yongjia Li, Yingjie Ji, Kaixin Zhang, Zhiyu Yang, Yi-Ming Yan
      First page: 1621
      Abstract: The pursuit of operational advancements in direct formic acid fuel cells (DFAFCs) necessitates the development of high-performance platinum (Pt)-based catalysts for formic acid electrooxidation (FAOR). However, FAOR on Pt-based catalysts follows a dual pathway mechanism, in which the direct pathway is a preferred route due to its efficient dehydrogenation process. Conversely, the indirect pathway results in the generation of adsorbed CO species, a process that deleteriously poisons the active sites of the catalyst, with CO species only being oxidizable at higher potentials, causing a significant compromise in catalyst performance. Herein, we have successfully synthesized Pt-C3N4@CNT, where three Pt clusters are precisely dispersed in a triplet form within the C3N4 by virtue of the unique structure of C3N4. The mass activity for the direct pathway (0.44 V) delivered a current density of 1.91 A mgPt−1, while the indirect pathway (0.86 V) had no obvious oxidation peak. The selectivity of Pt-C3N4@CNT catalysts for the direct pathway of FAOR was improved due to the special structure of C3N4, which facilitates the dispersion of Pt tri-atoms in the structure and the electronic interaction with Pt. In this study, we provide a new strategy for the development of highly active and selective catalysts for DFAFCs.
      Citation: Chemistry
      PubDate: 2023-07-26
      DOI: 10.3390/chemistry5030111
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1634-1644: Construction of an ATP-Activated
           Y-Shape DNA Probe for Smart miRNA Imaging in Living Cells

    • Authors: Wukun Zhong, Yanlin Zheng, Lei Huang, Chao Xing, Chunhua Lu
      First page: 1634
      Abstract: A stringent DNA probe to profile microRNA (miRNA) expression within a specific cell remains a key challenge in biology. To address this issue, an intracellular ATP-activated Y-DNA probe for accurate imaging of miRNA in living cells was designed. Y-DNA was based on the fabrication of tripartite function modules, which consisted of a folate (FA)-modified targeting module, an ATP aptamer-sealed driver, and a miRNA sensing module. The Y-DNA probe could be specifically activated by ATP after it efficiently internalized into FA-receptor-overexpressed cells based on caveolar-mediated endocytosis, leading to the activation of the miRNA sensing module. The activated Y-DNA probe allowed for the imaging of miRNA in living cells with high sensitivity. The design of the ATP-activated Y-DNA sensor opens the door for bioorthogonal miRNA imaging and promotes the development of various responsive DNA molecular probes with enhanced anti-interference ability for clinical diagnosis.
      Citation: Chemistry
      PubDate: 2023-07-27
      DOI: 10.3390/chemistry5030112
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1645-1655: Hydrothermally Synthesized
           Hydroxyapatite-Silica Composites with Enhanced Mechanical Properties for
           Bone Graft Applications

    • Authors: Atiek Rostika Noviyanti, Juliandri Juliandri, Engela Evy Ernawati, Haryono Haryono, Solihudin Solihudin, Dina Dwiyanti, Azman Ma’amor, Ferli Septi Irwansyah, Sharifuddin Bin Md Zain
      First page: 1645
      Abstract: The demand for synthetic bone grafts has increased in recent years. Hydroxyapatite (HA) is one of the highly suitable candidates as a bone graft material due to its excellent biocompatibility and high osteoconductive properties with low toxicity. HA has disadvantageous mechanical strength showing relatively fragile and brittle behavior due to its high hygroscopic properties. This leads to improper mechanical properties for such grafting applications. Therefore, HA should be combined with another material with similar biocompatibility and high hardness, such as SiO2. In this work, HA/SiO2 (HAS) composite material was prepared via a hydrothermal method to obtain the high purities of HA with a particle size of approximately 35 nm and around 50% crystallinity. It was found that the addition of SiO2 stimulated the composite system by forming an orthosilicic acid complex that can reduce the overall solution’s pH, thus contributing to the integrity and stability of the HAS composite. Therefore, higher SiO2 contents in the HAS composite can enhance its mechanical stability when immersed in simulated body fluid (SBF). Our work demonstrated that HAS can highly improve HA material’s hardness and mechanical stability under immersion of SBF. The Vickers test showed that the 0.05 GPa hardness in 10% SiO2 increased to 0.35 GPa hardness with the addition of 20% SiO2. The crystal structures of HAS were analyzed using X-ray diffraction, and the morphology of the HAS composites was observed under electron microscopy.
      Citation: Chemistry
      PubDate: 2023-07-28
      DOI: 10.3390/chemistry5030113
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1656-1680: Aptamer-Based Immune Drug Systems
           (AptIDCs) Potentiating Cancer Immunotherapy

    • Authors: Hongjie Xiong, Liu Liu, Xiaohui Liu, Hui Jiang, Xuemei Wang
      First page: 1656
      Abstract: Aptamers are artificial oligonucleotides with excellent molecule-targeting ability. Compared with monoclonal antibodies, aptamers have the advantages of low cost, no batch effect, and negligible immunogenicity, making them promising candidates for cancer immunotherapy. To date, a series of aptamer agonists/antagonists have been discovered and directly used to activate immune response, such as immune checkpoint blockade, immune costimulation, and cytokine regulation. By incorporating both tumor- and immune cell-targeting aptamers, multivalent bispecific aptamers were designed to pursue high tumor affinity and enhanced immune efficacy. More importantly, benefiting from feasible chemical modification and programmability, aptamers can be engineered with diverse nanomaterials (e.g., liposomes, hydrogels) and even living immune cells (e.g., NK cells, T cells). These aptamer-based assemblies exhibit powerful capabilities in targeted cargo delivery, regulation of cell–cell interactions, tumor immunogenicity activation, tumor microenvironment remodeling, etc., holding huge potential in boosting immunotherapeutic efficacy. In this review, we focus on the recent advances in aptamer-based immune drug systems (AptIDCs) and highlight their advantages in cancer immunotherapy. The current challenges and future prospects of this field are also pointed out in this paper.
      Citation: Chemistry
      PubDate: 2023-07-30
      DOI: 10.3390/chemistry5030114
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1681-1695: Rare Nuclearities and Unprecedented
           Structural Motifs in Manganese Cluster Chemistry from the Combined Use of
           Di-2-Pyridyl Ketone with Selected Diols

    • Authors: Katerina Skordi, Dimitris I. Alexandropoulos, Adeline D. Fournet, Nikos Panagiotou, Eleni E. Moushi, Constantina Papatriantafyllopoulou, George Christou, Anastasios J. Tasiopoulos
      First page: 1681
      Abstract: The combined use of di-2-pyridyl ketone ((py)2CO) with various diols in Mn cluster chemistry has afforded five new compounds, namely, [Mn11O2(OH)2{(py)2CO2}5(pd)(MeCO2)3(N3)3(NO3)2(DMF)4](NO3)∙2DMF∙H2O (1∙2DMF∙H2O), [Mn11O2(OH)2{(py)2CO2}5(mpd)(MeCO2)3(N3)3(NO3)2(DMF)4](NO3) (2), [Mn12O4(OH)2{(py)2CO2}4(mpd)2(Me3CCO2)4(NO3)4(H2O)6](NO3)2∙2MeCN (3∙2MeCN), [Mn4(OMe)2{(py)2C(OMe)O}2(2-hp)2(NO3)2(DMF)2] (4), and [Mn7{(py)2CO2}4(2-hp)4(NO3)2(DMF)2](ClO4)∙DMF (5∙DMF) ((py)2CO22− and (py)2C(OMe)O− = gem-diol and hemiketal derivatives of di-2-pyridyl ketone, pdH2 = 1,3-propanediol, mpdH2 = 2-metly-1,3-propanediol, 2-hpH2 = 2-(hydroxymethyl)phenol). Complexes 1 and 2 are isostructural, possessing an asymmetric [MnIII5MnII6(μ4-O)(μ3-O)(μ3-OH)(μ-OH)(μ3-OR)2(μ-OR)10(μ-N3)]8+ core. Compound 3 is based on a multilayer [MnIII8MnII4(μ4-O)2(μ3-O)2(μ3-OH)2(μ-OR)12]10+ core, while complex 4 comprises a defective dicubane core. The crystal structure of 5 reveals that it is based on an unusual non-planar [MnIII5MnII2(μ-OR)12]7+ core with a serpentine-like topology. Direct current (dc) magnetic susceptibility studies revealed the presence of dominant antiferromagnetic exchange interactions in complex 3, while ferromagnetic coupling between the Mn ions was detected in the case of compound 5. Fitting of the magnetic data for complex 4 revealed weak antiferromagnetic interactions along the peripheral MnII∙∙∙MnIII ions (Jwb = −0.33 (1) cm−1) and ferromagnetic interactions between the central MnIII∙∙∙MnIII ions (Jbb = 6.28 (1) cm−1).
      Citation: Chemistry
      PubDate: 2023-08-01
      DOI: 10.3390/chemistry5030115
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1696-1718: Peptide-Based Vectors for Gene

    • Authors: Juan Yang, Guo-Feng Luo
      First page: 1696
      Abstract: Gene therapy is the ultimate therapeutic technology for diseases related to gene abnormality. However, the use of DNA alone has serious problems, such as poor stability and difficulty in entering target cells. The development of a safe and efficient gene delivery system is the cornerstone of gene therapy. Of particular interest, multifunctional peptides are rationally designed as non-viral vectors for efficient gene delivery. As components of gene delivery vectors, these peptides play critically important roles in skeleton construction, the implementation of targeting strategies, cell membrane penetration, endosome rupture, and nuclear transport. In recent years, the research of functional peptide-based gene delivery vectors has made important progress in improving transfection efficiency. The latest research progress and future development direction of peptide-based gene delivery vectors are reviewed in this paper.
      Citation: Chemistry
      PubDate: 2023-08-05
      DOI: 10.3390/chemistry5030116
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1719-1721: Correction: Kurniawan et al.
           Vapor-Phase Oxidant-Free Dehydrogenation of 2,3- and 1,4-Butanediol over
           Cu/SiO2 Catalyst Prepared by Crown-Ether-Assisted Impregnation. Chemistry
           2023, 5, 406–421

    • Authors: Enggah Kurniawan, Shuya Hosaka, Masayuki Kobata, Yasuhiro Yamada, Satoshi Sato
      First page: 1719
      Abstract: In the published article “Vapor-Phase Oxidant-Free Dehydrogenation of 2,3- and 1,4-Butanediol over Cu/SiO2 Catalyst Prepared by Crown-Ether-Assisted Impregnation“ [...]
      Citation: Chemistry
      PubDate: 2023-08-07
      DOI: 10.3390/chemistry5030117
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1722-1744: New Functionalized Chitosan with
           Thio-Thiadiazole Derivative with Enhanced Inhibition of Pathogenic
           Bacteria, Plant Threatening Fungi, and Improvement of Seed Germination

    • Authors: Ahmed G. Ibrahim, Walid E. Elgammal, Ahmed M. Eid, Maha Alharbi, Ahmad E. Mohamed, Aisha A. M. Alayafi, Saber M. Hassan, Amr Fouda
      First page: 1722
      Abstract: In this study, a new modified chitosan conjugate (Chito-TZ) was developed via amide coupling between the acid chloride derivative of the methylthio-thidiazole compound and the free primary amino groups of chitosan. The product was characterized using several instrumental investigations, including Fourier-transform infrared spectroscopy (FT-IR), 1H-Nuclear magnetic resonance, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). XRD indicated that the crystalline pattern of chitosan was interrupted after chemical modification with the thiadiazole derivative. Broido’s model was used to determine the thermal activation energy Ea, and the results showed that the Ea for the first decomposition region of Chito-TZ is 24.70 KJ mol−1 lower than that required for chitosan (95.57 KJ mol−1), indicating the accelerating effect of the thiadiazole derivative on the thermal decomposition of Chito-TZ. The modified chitosan showed better antibacterial and antifungal activities than the non-modified chitosan; except for seed germination, chitosan was better. The Chito-TZ showed a low MIC value (25–50 µg mL−1) compared to Chito (50–100 µg mL−1). Moreover, the maximum inhibition percentages for plant-pathogenic fungi, Aspergillus niger, Fusarium oxysporum, and Fusarium solani, were attained at a concentration of 300 µg mL−1 with values of 35.4 ± 0.9–39.4 ± 1.7% for Chito and 45.2 ± 1.6–52.1 ± 1.3% for Chito-TZ. The highest germination percentages (%) of broad bean, shoot and root length and weight, and seed vigor index were obtained after Chito treatment with a concentration of 200 µg mL−1 compared to Chito-TZ.
      Citation: Chemistry
      PubDate: 2023-08-08
      DOI: 10.3390/chemistry5030118
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1745-1759: Ratiometric Detection of Zn2+ Using
           DNAzyme-Based Bioluminescence Resonance Energy Transfer Sensors

    • Authors: Yuting Wu, Whitney Lewis, Jing Luen Wai, Mengyi Xiong, Jiao Zheng, Zhenglin Yang, Chloe Gordon, Ying Lu, Siu Yee New, Xiao-Bing Zhang, Yi Lu
      First page: 1745
      Abstract: While fluorescent sensors have been developed for monitoring metal ions in health and diseases, they are limited by the requirement of an excitation light source that can lead to photobleaching and a high autofluorescence background. To address these issues, bioluminescence resonance energy transfer (BRET)-based protein or small molecule sensors have been developed; however, most of them are not highly selective nor generalizable to different metal ions. Taking advantage of the high selectivity and generalizability of DNAzymes, we report herein DNAzyme-based ratiometric sensors for Zn2+ based on BRET. The 8-17 DNAzyme was labeled with luciferase and Cy3. The proximity between luciferase and Cy3 permitted BRET when coelenterazine, the substrate for luciferase, was introduced. Adding samples containing Zn2+ resulted in a cleavage of the substrate strand, causing dehybridization of the DNAzyme construct, thus increasing the distance between Cy3 and luciferase and changing the BRET signals. Using these sensors, we detected Zn2+ in serum samples and achieved Zn2+ detection with a smartphone camera. Moreover, since the BRET pair is not the component that determines the selectivity of the sensors, this sensing platform has the potential to be adapted for the detection of other metal ions with other metal-dependent DNAzymes.
      Citation: Chemistry
      PubDate: 2023-08-08
      DOI: 10.3390/chemistry5030119
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1760-1769: Mechanochemistry through Extrusion:
           Opportunities for Nanomaterials Design and Catalysis in the Continuous

    • Authors: Oscar Trentin, Daniele Polidoro, Alvise Perosa, Enrique Rodríguez-Castellon, Daily Rodríguez-Padrón, Maurizio Selva
      First page: 1760
      Abstract: The potentialities of mechanochemistry trough extrusion have been investigated for the design of nanosized catalysts and their use in C-C bond-forming reactions. The mechanochemical approach proved successful for the synthesis of supported palladium nanoparticles with mean diameter within 6–10 nm, achieved by the reduction of Pd(II) acetate with ethylene glycol, in the absence of any solvent. A mesoporous N-doped carbon derived from chitin as a renewable biopolymer, was used as a support. Thereafter, the resulting nanomaterials were tested as catalysts to implement a second extrusion based-protocol for the Suzuki-Miyaura cross-coupling reaction of iodobenzene and phenylboronic acid. The conversion and the selectivity of the reaction were 81% and >99%, respectively, with a productivity of the desired derivative, biphenyl, of 41 mmol gcat−1 h−1.
      Citation: Chemistry
      PubDate: 2023-08-08
      DOI: 10.3390/chemistry5030120
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1770-1780: Blue-Emitting 2D- and 3D-Zinc
           Coordination Polymers Based on Schiff-Base Amino Acid Ligands

    • Authors: Rodavgi Karakousi, Pinelopi A. Tsami, Maria-Areti I. Spanoudaki, Scott J. Dalgarno, Vassileios C. Papadimitriou, Constantinos J. Milios
      First page: 1770
      Abstract: The solvothermal reaction of Zn(NO3)2·4H2O, 1-OH-2-naphthaldehyde, and 2-methylalanine (mAla) in MeOH leads to the formation of complex {[ZnL1]}2n (1) (H2L1 = the Schiff-base resulting from the reaction of 1-OH-2-naphthaldehyde and mAla) in good yields. The structure of the neutral species, as determined by single-crystal crystallography, describes a two-dimensional coordination polymer, with repeating {Zn2} units bridged by syn, anti-carboxylate groups of the Schiff-base ligands. Repeating the same reaction using glycine (gly) instead of mAla leads to the formation of complex {[ZnL2]·0.33MeOH}3n (2.0.33MeOH) (H2L2 = the Schiff-base resulting from the reaction of 1-OH-2-naphthaldehyde and gly), again in good yields. Complex 2 describes a three-dimensional coordination polymer based on {Zn2} building blocks, arranged by anti, anti-carboxylate groups in a 3D motif. Complexes 1 and 2 were found to strongly emit at ~435 nm (λexc = 317 nm) both in solution and solid state, with complex 2 displaying a slightly longer lifetime of τav = 2.45 ns vs. τav = 2.02 ns for 1.
      Citation: Chemistry
      PubDate: 2023-08-09
      DOI: 10.3390/chemistry5030121
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1781-1803: Recent Advances in Dynamic DNA

    • Authors: Qin Fan, Linzi Yang, Jie Chao
      First page: 1781
      Abstract: DNA nanotechnology has been widely used to fabricate precise nanometer-scale machines. In particular, dynamic DNA nanodevices have demonstrated their ability to mimic molecular motions and fluctuations in bion-anomic systems. The elaborately designed DNA nanomachines can conduct a variety of motions and functions with the input of specific commands. A dynamic DNA nanodevice with excellent rigidity and unprecedented processability allows for structural transformation or predictable behavior, showing great potential in tackling single-molecule sensing, drug delivery, molecular systems, and so on. Here, we first briefly introduce the development history of DNA nanotechnology. The driving energy of dynamic DNA nanomachines is also discussed with representative examples. The motor pattern of DNA nanomachines is classified into four parts including translational motion, shear motion, 360° rotation, and complex motion. This review aims to provide an overview of the latest reports on the dynamic DNA nanomachine and give a perspective on their future opportunities.
      Citation: Chemistry
      PubDate: 2023-08-10
      DOI: 10.3390/chemistry5030122
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1804-1814: Porous Natural Diamond with Embedded
           Metal (Pt0.50–Co0.50)

    • Authors: Evgeny Filatov, Aleksei Chepurov, Valeri Sonin, Andrey Zadesenets, Sergey Gromilov, Egor Zhimulev
      First page: 1804
      Abstract: Natural diamond crystals with a highly porous surface were used as substrates for synthesizing single-phase bimetallic Pt–Co nanoparticles at temperatures of 500 °C and 800 °C. The metal nanoparticles inside the pores were determined to take the form of single-phase Pt0.50Co0.50 solid solutions with different degrees of superstructure ordering. A detailed characterization of both nanoalloys revealed a tetragonal symmetry with a space group, P4/mmm. For the sample obtained at 500 °C, the lattice parameters were a = 2.673(2), c = 3.735(3) Å, and c/a = 1.397(1); for the samples obtained at 800 °C, the parameters were—a = 2.688(2), c = 3.697(3) Å, and c/a = 1.375(1). Within the experimental parameters, no significant chemical interaction of the diamond with the Pt–Co particles was identified. The results demonstrate a strong anchoring effect of the metallic material within the etching pores. The successful synthesis of bimetallic Pt–Co particles embedded inside the caverns can facilitate a study of their magnetic properties. The presence of Pt–Co in specific diamond compositions can also be used for marking diamond crystals as a means for their subtle identification, as well as confirming the possibility of capturing significant amounts of metal along with diamonds during their dissolution in the deep Earth.
      Citation: Chemistry
      PubDate: 2023-08-14
      DOI: 10.3390/chemistry5030123
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1815-1831: DNA Nanotechnology-Empowered
           Fluorescence Imaging of APE1 Activity

    • Authors: Hui He, Xiaojun Liu, Yuchen Wu, Lanlin Qi, Jin Huang, Yan Zhou, Jiahao Zeng, Kemin Wang, Xiaoxiao He
      First page: 1815
      Abstract: Apurinic/apyrimidinic endonuclease 1 (APE1), also known as redox factor-1 (Ref-1), is a multifunctional protein that exists widely in living organisms. It can specifically recognize and cleave the DNA in apurinic/apyrimidinic (AP) sites in the base excision repair (BER) pathway, as well as regulate the expression of genes to activate some transcription factors. The abnormal expression and disruptions in the biological functions of APE1 are linked to a number of diseases, including inflammation, immunodeficiency, and cancer. Hence, it is extremely desired to monitor the activity of APE1, acquiring a thorough understanding of the healing process of damaged DNA and making clinical diagnoses. Thanks to the advent of DNA nanotechnology, some nanodevices are used to image the activity of APE1 with great sensitivity and simplicity. In this review, we will summarize developments in DNA-nanotechnology-empowered fluorescence imaging in recent years for APE1 activity according to different types of DNA probes, which are classified into linear DNA probes, composite DNA nanomaterials, and three-dimensional (3D) DNA nanostructures. We also highlight the future research directions in the field of APE1 activity imaging.
      Citation: Chemistry
      PubDate: 2023-08-17
      DOI: 10.3390/chemistry5030124
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1832-1842: A Ratiometric Fluorescent Probe for pH
           Measurement over a Wide Range Composed of Three Types of Fluorophores
           Assembled on a DNA Scaffold

    • Authors: Eiji Nakata, Khongorzul Gerelbaatar, Mashal Asif, Hiroaki Konishi, Yuya Shibano, Peng Lin, Takashi Morii
      First page: 1832
      Abstract: The desirable properties of the sophisticated fluorescent pH probe are ratiometric detection properties and a wide detection range. In this study, three types of fluorophores with different fluorescence properties were assembled on a DNA origami nanostructure. DNA nanostructure has the advantage of being a scaffold that can assemble different types of fluorophores with control over their number and position. The defined number of three different fluorophores, i.e., pH-sensitive fluorescein (CF) and Oregon Green (OG), and pH-insensitive tetramethylrhodamine (CR), assembled on the DNA scaffold provided a ratiometric fluorescent pH probe with a wide pH detection range that could cover the variation of intracellular pH.
      Citation: Chemistry
      PubDate: 2023-08-17
      DOI: 10.3390/chemistry5030125
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1843-1854:
           Tris(3-nitropentane-2,4-dionato-κ2 O,O′) Complexes as a New
           Type of Highly Energetic Materials: Theoretical and Experimental

    • Authors: Danijela S. Kretić, Ivana S. Veljković, Dušan Ž. Veljković
      First page: 1843
      Abstract: Decreasing the sensitivity towards detonation of high-energy materials (HEMs) is the ultimate goal of numerous theoretical and experimental studies. It is known that positive electrostatic potential above the central areas of the molecular surface is related to high sensitivity towards the detonation of high-energy molecules. Coordination compounds offer additional structural features that can be used for the adjustment of the electrostatic potential values and sensitivity towards detonation of this class of HEM compounds. By a careful combination of the transition metal atoms and ligands, it is possible to achieve a fine-tuning of the values of the electrostatic potential on the surface of the chelate complexes. Here we combined Density Functional Theory calculations with experimental data to evaluate the high-energy properties of tris(3-nitropentane-2,4-dionato-κ2 O,O′) (nitro-tris(acetylacetonato)) complexes of Cr(III), Mn(III), Fe(III), and Co(III). Analysis of the Bond Dissociation Energies (BDE) of the C-NO2 bonds and Molecular Electrostatic Potentials (MEP) showed that these compounds may act as HEM molecules. Analysis of IR spectra and initiation of the Co(AcAc-NO2)3 complex in the open flame confirmed that these compounds act as high-energy molecules. The measured heat of combustion for the Co(AcAc-NO2)3 complex was 14,133 J/g, which confirms the high-energy properties of this compound. The results also indicated that the addition of chelate rings may be used as a new tool for controlling the sensitivity towards the detonation of high-energy coordination compounds.
      Citation: Chemistry
      PubDate: 2023-08-18
      DOI: 10.3390/chemistry5030126
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1855-1869: Optimization of Enzymatic Synthesis of
           D-Glucose-Based Surfactants Using Supported Aspergillus niger Lipase as

    • Authors: Alexis Spalletta, Nicolas Joly, Patrick Martin
      First page: 1855
      Abstract: Surfactants are amphiphilic molecules with the ability to modify the surface tension between two surfaces. They can be obtained by various methods, the main one being synthetic, from petroleum-based substrates. Their universal use in a wide range of fields has created a global market and, consequently, ecological, and economic expectations for their production. Biocatalyzed processes, involving enzymes, can address this objective with processes complying with the principles of green chemistry: energy saving, product selectivity, monodispersity, and reduction in the use of solvents, with energy eco-efficiency. For example, fatty-acid carbohydrate esters are biobased surfactants that can be synthesized by lipases. In this work, we were interested in the synthesis of D-glucose lauric ester, which presents interesting properties described in the literature, with Aspergillus niger lipase, rarely described with sugar substrates. We optimized the synthesis for different parameters and reaction media. This lipase appeared to be highly selective for 6-O-lauroyl-D-glucopyranose. However, the addition of DMSO (dimethyl sulfoxide) as a co-solvent displays a duality, increasing yields but leading to a loss of selectivity. In addition, DMSO generates more complex and energy-intensive purification and processing steps. Consequently, a bio-sourced alternative as co-solvent with 2MeTHF3one (2-methyltetrahydrofuran-3-one) is proposed to replace DMSO widely described in the literature.
      Citation: Chemistry
      PubDate: 2023-08-23
      DOI: 10.3390/chemistry5030127
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1870-1881: Insight into the Adsorption Behavior
           of Carbon Nanoparticles Derived from Coffee Skin Waste for Remediating
           Water Contaminated with Pharmaceutical Ingredients

    • Authors: Mutaz Salih, Babiker Y. Abdulkhair, Mansour Alotaibi
      First page: 1870
      Abstract: Coffee skins, a cheap, agricultural waste, were carbonized in a tubular furnace under a nitrogen stream and then ball milled to fabricate coffee skin-carbon-nanoparticles (CCNPs). SEM showed 35.6–41.6 nm particle size. The 26.64 and 43.16 peaks in the XRD indicated a cubic graphite lattice. The FT-IR broadband revealed a 2500–3500 cm−1 peak, suggesting an acidic O-H group. CCNPs possessed a type-H3-loop in the N2-adsorption-desorption analysis, with a surface of 105.638 m2 g−1. Thereafter, CCNPs were tested for ciprofloxacin (CPXN) adsorption, which reached equilibrium in 90 min. CCNPs captured 142.6 mg g−1 from 100 mg L−1 CPXN, and the 5:12 sorbent mass-to-solution volume ratio was suitable for treating up to 75 mg L−1 contamination. The qt dropped from 142.6 to 114.3 and 79.2 mg g−1 as the temperature rose from 20 °C to 35 °C and 50 °C, respectively, indicating exothermic adsorption. CPXN removal efficiency decreased below pH 5.0 and above pH 8.0. Kinetically, CPXN adsorption fits the second-order model and is controlled by the liquid-film mechanism, indicating its preference for the CCNPs’ surface. The adsorption agreement with the liquid-film and Freundlich models implied the ease of CPXN penetration into the CCNP inner shells and the multilayered accumulation of CPXN on the CCNPs’ surface. The negative ∆H° and ∆G° revealed the exothermic nature and spontaneity of CPXN adsorption onto the CCNP. The CCNPs showed an efficiency of 95.8% during four consecutive regeneration-reuse cycles with a relative standard deviation (RSD) of 3.1%, and the lowest efficiency in the fourth cycle was 92.8%.
      Citation: Chemistry
      PubDate: 2023-08-24
      DOI: 10.3390/chemistry5030128
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1882-1910: Self-Assembled DNA Nanospheres: Design
           and Applications

    • Authors: Jing Li, Xiaojun Liu, Jiaoli Wang, Qi Jiang, Minhui Chen, Wei Zhang, Yu Chen, Ying Pu, Jin Huang
      First page: 1882
      Abstract: Self-assembled DNA nanospheres, as versatile and ideal vehicles, have offered new opportunities to create intelligent delivery systems for precise bioimaging and cancer therapy, due to their good biostability and cell permeability, large loading capacity, and programmable self–assembly behaviors. DNA nanospheres can be synthesized by the self–assembly of Y–shaped DNA monomers, ultra–long single-stranded DNA (ssDNA), and even metal–DNA coordination. Interestingly, they are size–controllable by varying some parameters including concentration, reaction time, and mixing ratio. This review summarizes the design of DNA nanospheres and their extensive biomedical applications. First, the characteristics of DNA are briefly introduced, and different DNA nanostructures are mentioned. Then, the design of DNA nanospheres is emphasized and classified into three main categories, including Y–shaped DNA unit self-assembly by Watson–Crick base pairing, liquid crystallization and the dense packaging of ultra–long DNA strands generated via rolling circle amplification (RCA), and metal–DNA coordination–driven hybrids. Meanwhile, the advantages and disadvantages of different self–assembled DNA nanospheres are discussed, respectively. Next, the biomedical applications of DNA nanospheres are mainly focused on. Especially, DNA nanospheres serve as promising nanocarriers to deliver functional nucleic acids and drugs for biosensing, bioimaging, and therapeutics. Finally, the current challenges and perspectives for self-assembled DNA nanospheres in the future are provided.
      Citation: Chemistry
      PubDate: 2023-08-29
      DOI: 10.3390/chemistry5030129
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1911-1920: Structure, Stability and Binding
           Properties of Collagen-Binding Domains from Streptococcus mutans

    • Authors: Akari Nishi, Hikaru Matsui, Azumi Hirata, Atsushi Mukaiyama, Shun-ichi Tanaka, Takuya Yoshizawa, Hiroyoshi Matsumura, Ryota Nomura, Kazuhiko Nakano, Kazufumi Takano
      First page: 1911
      Abstract: Collagen-binding proteins (CBP), Cnm and Cbm, from Streptococcus mutans are involved in infective endocarditis caused by S. mutans because of their collagen-binding ability. In this study, we focused on the collagen-binding domain (CBD), which is responsible for the collagen-binding ability of CBP, and analyzed its structure, binding activity, and stability using CBD domain variants. The CBD consists of the N1 domain, linker, N2 domain, and latch (N1-N2~) as predicted from the amino acid sequences. The crystal structure of the Cnm/CBD was determined at a 1.81 Å resolution. N1_linker_N2 forms a ring structure that can enfold collagen molecules, and the latch interacts with N1 to form a ring clasp. N1 and N2 have similar immunoglobulin folds. The collagen-binding activities of Cbm/CBD and its domain variants were examined using ELISA. N1-N2~ bound to collagen with KD = 2.8 μM, and the latch-deleted variant (N1-N2) showed weaker binding (KD = 28 μM). The linker-deleted variant (N1N2~) and single-domain variants (N1 and N2) showed no binding activity, whereas the domain-swapped variant (N2-N1~) showed binding ability, indicating that the two N-domains and the linker are important for collagen binding. Thermal denaturation experiments showed that N1-N2 was slightly less stable than N1-N2~, and that N2 was more stable than N1. The results of this study provide a basis for the development of CBD inhibitors and applied research utilizing their collagen-binding ability.
      Citation: Chemistry
      PubDate: 2023-09-01
      DOI: 10.3390/chemistry5030130
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1921-1941: Antioxidant Determining Using
           Electrochemical Method

    • Authors: Rani Melati Sukma, Dyah Iswantini, Novik Nurhidayat, Mohamad Rafi, Dita Ariyanti
      First page: 1921
      Abstract: Antioxidants are very beneficial for health as they protect the body from the effects of free radicals on various degenerative diseases caused by food contamination, air pollution, sunlight, etc. In general, methods for measuring the capacity of antioxidants generally use accurate methods such as spectrophotometry and chromatography. Still, this takes time, accurate sample preparation, and must be performed in a laboratory with particular expertise. Therefore, a new, more practical method needs to be developed for determining antioxidants, namely the electrochemical method. The electrochemical method is a promising method to develop because it comes with several advantages, including high sensitivity and fast response. The electrochemical method discussed in this article reviews sensors, biosensors, and nanosensors. This paper comprehensively analyzes contemporary developments in electrochemical biosensor techniques and antioxidant evaluation methodologies. The discussion centers on utilizing multiple biosensors. Electrochemical biosensors have been determined to be prevalent in analyzing food quality, assessing active factor functionality, and screening practical components. The present study outlines the difficulties linked with electrochemical bio-sensor technology and provides insights into the potential avenues for future research in this domain.
      Citation: Chemistry
      PubDate: 2023-09-01
      DOI: 10.3390/chemistry5030131
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1942-1960: Encapsulation of Ciprofloxacin into a
           Cyclodextrin Polymer Matrix: The Complex Formation with Human Serum
           Albumin and In Vitro Studies

    • Authors: Anna A. Skuredina, Tatiana Yu. Kopnova, Natalya G. Belogurova, Elena V. Kudryashova
      First page: 1942
      Abstract: Here, we propose a drug delivery system for ciprofloxacin (CF) based on cyclodextrin (CD) polymer. We obtained a 3D matrix system with encapsulated drug molecules by crosslinking CF+CD non-covalent complexes with 1.6-hexamethylene isocyanate. The obtained polycarbamide (MAX-system) represents particles (~225 nm in diameter) that demonstrate CF’s sustained release. We investigated how the carrier affects the drug’s interaction with the biological macromolecule human serum albumin (HSA) and CF’s antibacterial properties. Compared to a binary CF–HSA system, CD decreases CF’s binding efficiency to HSA by two times, whereas CF encapsulation in a polymer matrix doubles the Ka value and prevents protein aggregation. The changes in HSA’s secondary structure indicate no alterations in the main mechanism of complex formation between CF and HSA in the presence of both CD-based carriers. CD as well as MAX systems practically do not change CF’s activity against E. coli and B. subtilis, but for MAX systems, prolonged action is realized due to CF’s sustained release. We believe that our findings are important for the further development of new, efficient drug forms.
      Citation: Chemistry
      PubDate: 2023-09-01
      DOI: 10.3390/chemistry5030132
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1961-1989: Syntheses, Crystal and Electronic
           Structures of Rhodium and Iridium Pyridine Di-Imine Complexes with O- and
           S-Donor Ligands: (Hydroxido, Methoxido and Thiolato)

    • Authors: Stephan, Völker, Schreyer, Burger
      First page: 1961
      Abstract: The syntheses of new neutral square-planar pyridine di-imine rhodium and iridium complexes with O- and S-donor (OH, OR, SH, SMe and SPh) ligands along with analogous cationic compounds are reported. Their crystal and electronic structures are investigated in detail with a focus on the non-innocence/innocence of the PDI ligand. The oxidation states of the metal centers were analyzed by a variety of experimental (XPS and XAS) and theoretical (LOBA, EOS and OSLO) methods. The dπ-pπ interaction between the metal centers and the π-donor ligands was investigated by theoretical methods and revealed the partial multiple-bond character of the M-O,S bonds. Experimental support is provided by a sizable barrier for the rotation about the Ir-S bond in the methyl thiolato complex and confirmed by DFT and LNO-CCSD(T) calculations. This was corroborated by the high Ir-O and Ir-S bond dissociation enthalpies calculated at the PNO-CCSD(T) level.
      Citation: Chemistry
      PubDate: 2023-09-05
      DOI: 10.3390/chemistry5030133
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1990-1997: Solid State Fabrication of Copper
           Nanoclusters and Supraparticles

    • Authors: Rui Wang, Yunyun Zheng, Yunsheng Xia
      First page: 1990
      Abstract: In this study, we present solid state processes for the fabrication of copper nanoclusters (NCs) and hierarchical supraparticles (SPs). To achieve this, copper salt and thiols are mixed and are then grinded for 10–15 min, and the nano-products are thereby obtained. Interestingly, it was found in this study that the formation of the NCs or SPs is completely dependent on the grinding methods that are used: with mechanical grinding, the products are several nanometer-sized NCs, whereas manual grinding in an agate mortar can obtain Cu SPs with diameters as low as 10 nm all the way up to 200 nm. The photoluminescence emission wavelength of the nano-products is located at ~680 nm. The Stokes shift of the obtained nanomaterials is more than 300 nm. The emission quantum yields of the Cu NCs and SPs are as high as 47.5% and 63%, respectively. Due to their facile fabrication processes and their favorable optical properties, the two as-prepared types of copper nano-materials exhibit great potential for bio-imaging and bio-sensing applications.
      Citation: Chemistry
      PubDate: 2023-09-06
      DOI: 10.3390/chemistry5030134
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 1998-2008: Expanding Heteroaromatic and
           2-Aminosugar Chemical Space Accessible from the Biopolymer Chitin

    • Authors: Thaís A. Rossa, Jessica C. Neville, Seongmin Paul Jun, Tilo Söhnel, Jonathan Sperry
      First page: 1998
      Abstract: Herein, we report the expansion of chemical space available from chitin, accessible via the biogenic N-platforms 3A5AF, M4A2C, and di-HAF. The biologically active heteroaromatics furo[3,2-d]pyrimidin-4-one and furo[3,2-d]pyrimidin-4-amine can be selectively accessed from 3A5AF and M4A2C, respectively. The chiral pool synthon di-HAF is a viable substrate for Achmatowicz rearrangement, providing streamlined access to 2-aminosugars possessing a versatile hydroxymethyl group at C5.
      Citation: Chemistry
      PubDate: 2023-09-09
      DOI: 10.3390/chemistry5030135
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 2009-2024: The Antimicrobial and Mosquitocidal
           Activity of Green Magnesium Oxide Nanoparticles Synthesized by an Aqueous
           Peel Extract of Punica granatum

    • Authors: Amr Fouda, Khalid S. Alshallash, Mohammed I. Alghonaim, Ahmed M. Eid, Ahmed M. Alemam, Mohamed A. Awad, Mohammed F. Hamza
      First page: 2009
      Abstract: An aqueous extract of Punica granatum peel was used as a biocatalyst for magnesium oxide nanoparticle (MgO-NP) synthesis, which was characterized via UV-Vis spectroscopy, TEM, EDX, FT-IR, XRD, DLS, and zeta potential. Data showed the efficacy of the plant aqueous extract in forming spherical, crystalline-nature, well-arranged MgO-NPs with sizes in the range of 10–45 nm with average sizes of 24.82 ± 8.85 nm. Moreover, EDX analysis revealed that the highest weight and atomic percentages were recorded for Mg and O ions. The green synthesized MgO-NPs showed antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, E. coli, Pseudomonas aeruginosa, and Candida albicans in a concentration-dependent manner with clear zones in the range of 8.7 ± 0.6 to 19.7 ± 0.5 mm with various concentrations. Also, the MIC value was varied to be 25 µg mL−1 for Gram-negative bacteria, B. subtilis, and C. albicans and 50 µg mL−1 for S. aureus. Moreover, MgO-NPs showed high activity against the 3rd-instar larvae of Culex quinquefasciatus. The mortality percentages were concentration- and time-dependent. Data analysis showed that the highest mortality was 88.3 ± 3.2%, attained at a concentration of 100 µg mL−1 after 72 h. Also, all originated pupae were malformed and did not hatch to adults, with mortality percentages of 100% at all concentrations. Overall, the P. granatum-mediated MgO-NPs showed promising activity in inhibiting the growth of pathogenic microbes and the hatching of C. quinquefasciatus larvae to adults.
      Citation: Chemistry
      PubDate: 2023-09-12
      DOI: 10.3390/chemistry5030136
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 2025-2037: High Thermal Stability of Enzyme-MOF
           Composites at 180 °C

    • Authors: Shitong Cui, Jun Ge
      First page: 2025
      Abstract: Encapsulating enzymes in a tailored scaffold is of great potential in industrial enzymatic catalysis, which can enhance the stability of enzymes thus expanding their applications. Metal–organic frameworks (MOFs) are emerging as promising candidates for enzyme encapsulation due to their precise pore structure, ease of synthesis and good biocompatibility. Despite the fact that enzymes encapsulated in MOFs can obtain enhanced stability, there has been little discussion about the thermal stability of enzyme-MOF composites in solid state under extremely high temperatures. Herein, we fabricated the enzyme-MOF composites, CALB-ZIF-8, via a convenient coprecipitation method in aqueous solution, which exhibited good thermal stability at 180 °C. It was found that the activity of CALB encapsulated in ZIF-8 retained nearly ~80% after heating for 10 min at 180 °C. A finite element method was applied to investigate the heat transfer process within a ZIF-8 model, indicating that the air filled in cavities of ZIF-8 played a significant role in hindering the heat transfer and this may be an important reason for the outstanding thermal stability of CALB-ZIF-8 at 180 °C, which paves a new path for expanding the industrial application of enzyme-MOF composites.
      Citation: Chemistry
      PubDate: 2023-09-19
      DOI: 10.3390/chemistry5030137
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 2038-2055: In Pursuit of Next Generation
           N-Heterocyclic Carbene-Stabilized Copper and Silver Precursors for
           Metalorganic Chemical Vapor Deposition and Atomic Layer Deposition

    • Authors: Ilamparithy Selvakumar, Nils Boysen, Marco Bürger, Anjana Devi
      First page: 2038
      Abstract: Volatile, reactive, and thermally stable organometallic copper and silver complexes are of significant interest as precursors for the metalorganic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD) of ultra-thin metallic films. Well-established CuI and AgI precursors are commonly stabilized by halogens, phosphorous, silicon, and oxygen, potentially leading to the incorporation of these elements as impurities in the thin films. These precursors are typically stabilized by a neutral and anionic ligand. Recent advancements were established by the stabilization of these complexes using N-heterocyclic carbenes (NHCs) as neutral ligands. To further enhance the reactivity, in this study the anionic ligand is sequentially changed from β-diketonates to β-ketoiminates and β-diketiminates, yielding two new CuI and two new AgI NHC-stabilized complexes in the general form of [M(NHC) (R)] (M = Cu, Ag; R = β-ketoiminate, β-diketiminate). The synthesized complexes were comparatively analyzed in solid, dissolved, and gaseous states. Furthermore, the thermal properties were investigated to assess their potential application in MOCVD or ALD. Among the newly synthesized complexes, the β-diketiminate-based [Cu(tBuNHC) (NacNacMe)] was identified to be the most suitable candidate as a precursor for Cu thin film deposition. The resulting halogen-, oxygen-, and silicon-free CuI and AgI precursors for MOCVD and ALD applications are established for the first time and set a new baseline for coinage metal precursors.
      Citation: Chemistry
      PubDate: 2023-09-20
      DOI: 10.3390/chemistry5030138
      Issue No: Vol. 5, No. 3 (2023)
  • Chemistry, Vol. 5, Pages 703-712: Nature Inspired Manganese(III)-Calcium
           Complexes: Towards Synthetic Models for the WOC of PSII

    • Authors: Joaquin Bonelli Blasco, Sara Mauri Querol, Kevin Consuegra Naranjo, E. Carolina Sañudo
      First page: 703
      Abstract: For some time, the presence of high oxidation state Mn ions and Ca(II) in the active center of Photosystem II has been known. However, coordination complexes that combine both Mn(III) and Ca(II) have been difficult to obtain, with only a handful of examples reported. In this paper we report the synthesis of two new Mn(III)-Ca(II) complexes, 1 [Pr2NH2]3[Mn6CaO2(OH)(OMe)3(SALO)6 (SALOH)3] and 2 [Mn18Ca6O12(OH)6(MeO)12(PhCOO)18(MeOH)6]. The complexes have been characterized by single-crystal X-ray diffraction to establish the oxidation state of manganese. The use of salicylato ligands with tert-butyl substituents leads to effective encapsulation of a Ca(II) ion in a cavity that has both hydrophobic and hydrophilic regions, mimicking the enzyme environment.
      Citation: Chemistry
      PubDate: 2023-03-23
      DOI: 10.3390/chemistry5020049
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 713-719: Molecular Modeling and Potential Ca2+
           Channel Blocker Activity of Diphenylmethoxypiperidine Derivatives

    • Authors: Victor M. Pulgar, Jill Harp, Tony E. Reeves
      First page: 713
      Abstract: Molecular interactions of 4-diphenylmethoxy-1-methylpiperidine derivatives with the calcium channel CaV1.1 (pdb:6JP5) are described. All the compounds tested, previously shown to inhibit adrenergic vascular contractions, display similar binding energetics and interactions with the trans-membrane domain of 6JP5 on the opposite side relative to the channel pore, where nifedipine, a known dihydropyridine Ca2+ channel blocker binds. Additionally, the compounds tested inhibit Ca2+-dependent contractions in isolated mouse mesenteric arteries. Thus, diphenylpyraline analogs may exert their anticontractile effects, at least partially, by blocking vascular Ca2+ channels.
      Citation: Chemistry
      PubDate: 2023-03-25
      DOI: 10.3390/chemistry5020050
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 720-729: UiO-66 MOF-Derived Ru@ZrO2 Catalysts for
           Photo-Thermal CO2 Hydrogenation

    • Authors: Fernando Almazán, Marta Lafuente, Amaya Echarte, Mikel Imizcoz, Ismael Pellejero, Luis M. Gandía
      First page: 720
      Abstract: The use of metal–organic frameworks (MOFs) as templates or precursors in the manufacture of heterogeneous catalysts is highly attractive due to the transfer of MOFs’ inherent porosity and homogeneous metallic distribution to the derived structure. Herein, we report on the preparation of MOF-derived Ru@ZrO2 catalysts by controlled thermal treatment of zirconium-based MOF UiO-66 with ruthenium moieties. Ru3+ (3 or 10 mol%) precursor was added to UiO-66 synthesis and, subsequently, the as-synthesized hybrid structure was calcined in flowing air at different temperatures (400–600 °C) to obtain ZrO2-derived oxides doped with highly dispersed Ru metallic clusters. The materials were tested for the catalytic photo-thermal conversion of CO2 to CH4. Methanation experiments were conducted in a continuous flow (feed flow rate of 5 sccm and 1:4 CO2 to H2 molar ratio) reactor at temperatures from 80 to 300 °C. Ru0.10@ZrO2 catalyst calcined at 600 °C was able to hydrogenate CO2 to CH4 with production rates up to 65 mmolCH4·gcat.–1·h–1, CH4 yield of 80% and nearly 100% selectivity at 300 °C. The effect of the illumination was investigated with this catalyst using a high-power visible LED. A CO2 conversion enhancement from 18% to 38% was measured when 24 sun of visible LED radiation was applied, mainly due to the increase in the temperature as a result of the efficient absorption of the radiation received. MOF-derived Ru@ZrO2 catalysts have resulted to be noticeably active materials for the photo-thermal hydrogenation of CO2 for the purpose of the production of carbon-neutral methane. A remarkable effect of the ZrO2 crystalline phase on the CH4 selectivity has been found, with monoclinic zirconia being much more selective to CH4 than its cubic allotrope.
      Citation: Chemistry
      PubDate: 2023-03-25
      DOI: 10.3390/chemistry5020051
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 730-752: Synthesis and Structure of COE-11, a New
           Borosilicate Zeolite with a Two-Dimensional Pore System of 12-Ring

    • Authors: Bernd Marler, Hermann Gies, Trees De Baerdemaeker, Ulrich Müller, Andrei-Nicolae Parvulescu, Weiping Zhang, Toshiyuki Yokoi, Feng-Shou Xiao, Xiangju Meng, Dirk De Vos, Ute Kolb
      First page: 730
      Abstract: The new zeolite, COE-11, was synthesized at 155 °C to 168 °C by hydrothermal synthesis from a reaction mixture of SiO2/tetraethylammonium hydroxide/H3BO3/NaOH/H2O. Because tetraethylammonium is an unspecific structure directing agent, COE-11 crystallizes in all cases together with at least one impurity phase from a selection of phases: zeolite types *BEA, CHA, FER, MFI, MOR, MTW; the layered silicates magadiite and kenyaite; and searlsite and silica polymorph quartz. The crystal structure was solved from 3D electron diffraction (3D ED) data. Subsequent structure refinements of X-ray powder diffraction (PXRD) data and single crystal electron diffraction data converged to residual values of RF = 0.039, chi2 = 3.6 (PXRD) and RF = 21.81% (3D ED) confirming the structure model. COE-11 crystallizes in space group C2 with unit cell dimensions of a0 = 17.3494(11) Å, b0 = 17.3409(11) Å, c0 = 14.2789(4) Å and β = 113.762(2) °. The structure of COE-11 is characterized by a microporous borosilicate framework with intersecting, highly elliptical 12-ring channels running parallel (110) and (1–10) and forming a two-dimensional pore system. The Rietveld refinement provided a hint that boron partly substitutes silicon on three specific T sites of the framework. The idealized chemical composition of as-made COE-11 is [(CH3CH2)4N]4[B4Si62O132] per unit cell. Physico-chemical characterization using solid-state NMR spectroscopy, SEM, TG-DTA, and ATR-FTIR spectroscopy confirmed that COE-11 is a microporous borosilicate zeolite. COE-11 is structurally closely related to zeolite beta polymorph B but differs concerning the dimensionality of the pore system, which is 2D instead of 3D.
      Citation: Chemistry
      PubDate: 2023-03-28
      DOI: 10.3390/chemistry5020052
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 753-761: Defective PrOx for Efficient
           Electrochemical NO2−-to-NH3 in a Wide Potential Range

    • Authors: Shunhan Jia, Xingxing Tan, Limin Wu, Jiaqi Feng, Libing Zhang, Liang Xu, Ruhan Wang, Xiaofu Sun, Buxing Han
      First page: 753
      Abstract: Electrocatalytic reduction of nitrite (NO2−) is a sustainable and carbon-neutral approach to producing green ammonia (NH3). We herein report the first work on building defects on PrOx for electrochemical NO2− reduction to NH3, and demonstrate a high NH3 yield of 2870 μg h−1 cm−2 at the optimal potential of –0.7 V with a faradaic efficiency (FE) of 97.6% and excellent FEs of >94% at a wide given potential range (−0.5 to −0.8 V). The kinetic isotope effect (KIE) study suggested that the reaction involved promoted hydrogenation. Theoretical calculations clarified that there was an accelerated rate-determining step of NO2− reduction on PrOx. The results also indicated that PrOx could be durable for long-term electrosynthesis and cycling tests.
      Citation: Chemistry
      PubDate: 2023-03-29
      DOI: 10.3390/chemistry5020053
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 762-777: Insight into Tyrosine-Containing
           Pharmaceuticals as Potential Inhibitors of SARS-CoV-2 3CLpro and NSP16:
           Structural Analysis, Docking Studies, Molecular Dynamics Simulations, and
           Density Functional Theory Investigations

    • Authors: Mohamed R. Elamin, Tarek A. Yousef, Amin O. Elzupir
      First page: 762
      Abstract: Tyrosine-containing pharmaceuticals’ (TPh) potential to inhibit SARS CoV-2 3-chymotrypsin-like proteases (3CLpro) and nonstructural protein 16 (NSP16) has been explored using docking studies, molecular dynamics simulations, and density functional theory. The TPh with FDA approval showed excellent contact with the active site pockets of 3CLpro and NSP16. Their binding affinity scores ranged from −5.8 to −4.9 kcal/mol and −6.3 to −4.8 for 3CLpro and NSP16, respectively. A 100-ns molecular dynamics simulation confirmed the stability of the carbidopa/NSP16 complex and N-acetyl tyrosine with both target enzymes. Further, the HOMO-LUMO transitions, molecular orbitals, and dipole moments of carbidopa, droxidopa, and N-acetyl tyrosine were computed using density functional theory (DFT). Considering N-acetyl tyrosine and carbidopa’s substantial inhibitory activity, it is recommended to investigate them further in order to explore their application for the treatment of COVID-19 or any other coronaviruses in the future.
      Citation: Chemistry
      PubDate: 2023-04-03
      DOI: 10.3390/chemistry5020054
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 778-788: Effects of Two Amphiphilic Diesters of
           L-Ascorbic Acid on the Oxidative Stability of Rabbit Meatballs

    • Authors: Giulia Secci, Antonella Capperucci, Adja Cristina Lira de Medeiros, Luca Pellicciari, Damiano Tanini, Giuliana Parisi
      First page: 778
      Abstract: Lipid oxidation involves a cascade of phenomena leading to serious impairments of meat quality during storage. Novel strategies for lipid protection are therefore highly desirable. Herein, two amphiphilic diesters of L-ascorbic acid with myristic (DA) and stearic (DB) acids were synthesised and added at a 0.1% (w/w) to minced rabbit meat before preparing meatballs. Then, pH, colour indexes, weight loss, fatty acid profile and primary and secondary lipid oxidation products were analysed for meatballs treated with DA (n = 16), DB (n = 16), or not treated (C, n = 16), and stored for 80 days at −10 °C. Results showed that DA and DB did not specifically prevent weight loss and lipid oxidation. Nevertheless, the addition of DA on stored rabbit meatballs seemed to prevent colour modification and reduced (p = 0.0613) TBARS levels in the treated stored meat. For these reasons, further investigations on the properties of L-ascorbyl diesters on the oxidative stability of meat will likely be performed.
      Citation: Chemistry
      PubDate: 2023-04-03
      DOI: 10.3390/chemistry5020055
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 789-799: Graphene Oxide-Assisted Aptamer-Based
           Fluorescent Detection of Tetracycline Antibiotics

    • Authors: Yang Zhou, Juewen Liu
      First page: 789
      Abstract: Tetracyclines are a group of common antibiotics, but owing to their toxicity, most of them are only used in animal husbandry and veterinary medicine. A DNA aptamer for tetracyclines has recently been reported. Upon aptamer binding, the fluorescence of tetracyclines was enhanced. This unique fluorescence enhancement was used to selectively detect the tetracyclines. The purpose of this study was to use graphene oxide (GO) to suppress the background fluorescence for enhanced detection. First, the adsorption of doxycycline on GO was studied. At pH 8.0, 82.7% of doxycycline was adsorbed by GO, and adding 2 µM aptamer desorbed 55.4% of doxycycline. With GO, the signal increase was comparable from pH 6 to 8, whereas without GO, the increase was significantly lower at pH 8. Under optimized condition, a detection limit of 1.6 nM doxycycline was achieved at pH 8.0 in the presence of GO, whereas without GO, the detection limit was 18.9 nM. This is an interesting example of the use of nanomaterials to enhance the performance of aptamer-based biosensors.
      Citation: Chemistry
      PubDate: 2023-04-04
      DOI: 10.3390/chemistry5020056
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 800-812: Production of Alkyl Levulinates from
           Carbohydrate-Derived Chemical Intermediates Using Phosphotungstic Acid
           Supported on Humin-Derived Activated Carbon (PTA/HAC) as a Recyclable
           Heterogeneous Acid Catalyst

    • Authors: Nivedha Vinod, Saikat Dutta
      First page: 800
      Abstract: This work reports a straightforward and high-yielding synthesis of alkyl levulinates (ALs), a class of promising biofuel, renewable solvent, and chemical feedstock of renewable origin. ALs were prepared by the acid-catalyzed esterification of levulinic acid (LA) and by the alcoholysis of carbohydrate-derived chemical platforms, such as furfuryl alcohol (FAL) and α-angelica lactone (α-AGL). Phosphotungstic acid (PTA) was chosen as the solid acid catalyst for the transformation, which was heterogenized on humin-derived activated carbon (HAC) for superior recyclability. Using HAC as catalyst support expands the scope of valorizing humin, a complex furanic resin produced inevitably as a side product (often considered waste) during the acid-catalyzed hydrolysis/dehydration of sugars and polymeric carbohydrates. Under optimized conditions (150 °C, 7 h, 25 wt.% of 20%PTA/HAC-600 catalyst), ethyl levulinate (EL) was obtained in an 85% isolated yield starting from FAL. Using the general synthetic protocol, EL was isolated in 88% and 84% yields from LA and α-AGL, respectively. The 20%PTA/HAC-600 catalyst was successfully recovered from the reaction mixture and recycled for five cycles. A marginal loss in the yield of ALs was observed in consecutive catalytic cycles due to partial leaching of PTA from the HAC support.
      Citation: Chemistry
      PubDate: 2023-04-06
      DOI: 10.3390/chemistry5020057
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 813-833: Coinage Metal Complexes Containing
           Perfluorinated Carboxylates

    • Authors: Robin Piani, Björn B. Beele, Jörg Rust, Christian W. Lehmann, Fabian Mohr
      First page: 813
      Abstract: A variety of coinage-metal complexes containing perfluorinated carboxylate ligands, together with their structures and thermal behavior, are reported. The silver(I) salts were accessible from the direct reaction of Ag2O with the acids in toluene. Their gold(I) phosphine counterparts formed in high yields by transmetallation using the silver(I) salts. Some structurally unique, mixed-metal (Au,Ag) complexes formed upon combining solutions of the silver(I) salts with the gold(I) phosphine carboxylates. The reduction of dinuclear copper(II) compounds containing perfluorinated carboxylates with triphenylphosphine resulted in the formation of the corresponding copper(I) tris(phosphine) complexes. X-ray structures of representative complexes, together with IR- and TGA data, are reported.
      Citation: Chemistry
      PubDate: 2023-04-08
      DOI: 10.3390/chemistry5020058
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 834-885: Combining Two Types of Boron in One
           Molecule (To the 60th Anniversary of the First Synthesis of Carborane)

    • Authors: Igor B. Sivaev
      First page: 834
      Abstract: This review is an attempt to bring together the data from the literature on the synthesis and properties of icosahedral carborane derivatives, in which exo-polyhedral three- and four-coordinated boron substituents are attached directly to the carborane cage through boron–carbon or boron–boron bonds. Various classes of compounds are considered, including carboranyl aryl boranes, boronic acids and their derivatives, boroles, diazaboroles, etc. Particular attention is paid to carborane-fused heterocycles containing boron atoms.
      Citation: Chemistry
      PubDate: 2023-04-11
      DOI: 10.3390/chemistry5020059
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 886-899: Hydrogen Evolution upon Ammonia Borane
           Solvolysis: Comparison between the Hydrolysis and Methanolysis Reactions

    • Authors: Naixin Kang, Changlong Wang, Didier Astruc
      First page: 886
      Abstract: Hydrogen (H2) production is a key challenge for green carbon-free sustainable energy. Among the H2 evolution methods from H-rich materials, ammonia borane (AB) solvolysis stands as a privileged source under ambient and sub-ambient conditions given its stability, non-toxicity, and solubility in protic solvents, provided suitable and optimized nanocatalysts are used. In this paper dedicated to Prof. Avelino Corma, we comparatively review AB hydrolysis and alcoholysis (mostly methanolysis) in terms of nanocatalyst performances and discuss the advantages and inconveniences of these two AB solvolysis methods including AB regeneration.
      Citation: Chemistry
      PubDate: 2023-04-13
      DOI: 10.3390/chemistry5020060
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 900-911: Room Temperature Surfactant-Free
           Synthesis of Gold Nanoparticles in Alkaline Ethylene Glycol

    • Authors: Rasmussen, Nielsen, Quinson
      First page: 900
      Abstract: Gold nanoparticles are easily obtained by a range of room temperature processes. In particular, polyols-based syntheses performed in alkaline conditions without the need for surfactants lead to small size nanoparticles around 10 nm in diameter. While highly viscous polyols, such as glycerol, have been the most studied polyols with which to perform the reaction, the use of alternative alcohols with lower viscosity could benefit the processing of the nanoparticles. Here, we show that ethylene glycol is a suitable alternative to glycerol. Via a study comprising more than 70 experiments overall, we identified that the key parameters by which to control nanoparticle size and colloidal stability are the amount of base used and the amount of ethylene glycol. Too-high or too-low values of base and/or ethylene glycol do not lead to stable colloidal nanoparticles. An optimal Base/Gold molar ratio is around 4 and an optimal amount of ethylene glycol is around 30 v.% to obtain stable ca. 10 nm Au NPs and to develop a green room temperature surfactant-free colloidal synthesis of gold nanoparticles.
      Citation: Chemistry
      PubDate: 2023-04-14
      DOI: 10.3390/chemistry5020061
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 912-933: Phosphine Functionalized CpC Ligands and
           Their Metal Complexes

    • Authors: Florian Nährig, Yu Sun, Werner R. Thiel
      First page: 912
      Abstract: Simple nucleophilic aliphatic substitution gives access to mono- and diphosphine ligands with a CpC group in the backbone. The monophosphine ligand coordinates to gold(I) via the phosphine site, to thallium(I) via the cyclopentadienyl site and to ruthenium(II) via a combination of both, resulting in an ansa-type structure. Coordination with the cyclopentadiene site is not possible for the diphosphine ligand. In this case, monodentate coordination to gold(I) and bidentate coordination to the [PdCl(μ2-Cl)]2, the [Rh(CO)(μ2-Cl)]2, and the Rh(CO)Cl fragment is observed, showing the variability in coordination modes possible for the long-chain diphosphine ligand. Ligands and complexes were characterized by means of NMR and IR spectroscopy, elemental analysis and X-ray structure analysis.
      Citation: Chemistry
      PubDate: 2023-04-18
      DOI: 10.3390/chemistry5020062
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 934-947: Stabilization of 2-Pyridyltellurium(II)
           Derivatives by Oxidorhenium(V) Complexes

    • Authors: Felipe Dornelles da Silva, Maximilian Roca Jungfer, Adelheid Hagenbach, Ernesto Schulz Lang, Ulrich Abram
      First page: 934
      Abstract: Zwitterionic compounds such as pyridine-containing tellurenyl compounds are interesting building blocks for heterometallic assemblies. They can act as ambiphilic donor/acceptors as is shown by the products of reactions of the zwitterions HpyTeCl2 or HCF3pyTeCl2 with the rhenium(V) complex [ReOCl3(PPh3)2]. The products have a composition of [ReO2Cl(pyTeCl)(PPh3)2] and [ReO2Cl(CF3pyTeCl)(PPh3)2] with central {O=Re=O…Te(Cl)p⏠y}+ units. The Re-O bonds in the products are elongated by approximately 0.1 Å compared with those to the terminal oxido ligands and establish Te…O contacts. Thus, the normally easily assigned concept of oxidation states established at the two metal ions becomes questionable (ReV/TeII vs. ReIII/TeIV). A simple bond length consideration rather leads to a description with the coordination of a mesityltellurenyl(II) chloride unit to an oxido ligand of the Re(V) center, but the oxidation of the tellurium ion and the formation of a tellurinic acid chloride cannot be ruled out completely from an analysis of the solid-state structures. DFT calculations (QTAIM, NBO analysis) give clear support for the formation of a Re(V) dioxide complex donating into an organotellurium(II) chloride and the alternative description can at most be regarded as a less favored resonance structure.
      Citation: Chemistry
      PubDate: 2023-04-18
      DOI: 10.3390/chemistry5020063
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 948-964: Synthesis of
           5-Metalla-Spiro[4.5]Heterodecenes by [1,4]-Cycloaddition Reaction of Group
           13 Diyls with 1,2-Diketones

    • Authors: Hanns M. Weinert, Christoph Wölper, Stephan Schulz
      First page: 948
      Abstract: Monovalent group 13 diyls are versatile reagents in oxidative addition reactions. We report here [1,4]-cycloaddition reactions of β-diketiminate-substituted diyls LM (M = Al, Ga, In, Tl; L = HC[C(Me)NDipp]2, Dipp = 2,6-iPr2C6H3) with various 1,2-diketones to give 5-metalla-spiro[4.5]heterodecenes 1, 4–6, and 8–10, respectively. In contrast, the reaction of LTl with acenaphthenequinone gave the [2,3]-cycloaddition product 7, with Tl remaining in the +1 oxidation state. Compound 1 also reacted with a second equivalent of butanedione as well as with benzaldehyde in aldol-type addition reactions to the corresponding α,β-hydroxyketones 2 and 3, while a reductive activation of a benzene ring was observed in the reaction of benzil with two equivalents of LAl to give the 1,4-aluminacyclohex-2,4-dien 12. In addition, the reaction of L’BCl2 (L = HC[C(Me)NC6F5]2) with one equivalent of benzil in the presence of KC8 gave the corresponding 5-bora-spiro[4.5]heterodecene 13, whereas the hydroboration reaction of butanedione with L’BH2 (14), which was obtained from the reaction of L’BCl2 with L-selectride, failed to give the saturated 5-bora-spiro[4.5]heterodecane.
      Citation: Chemistry
      PubDate: 2023-04-20
      DOI: 10.3390/chemistry5020064
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 965-977: Synthesis, Structure, and Spectroscopic
           Properties of Luminescent Coordination Polymers Based on the
           2,5-Dimethoxyterephthalate Linker

    • Authors: Aimée E. L. Cammiade, Laura Straub, David van Gerven, Mathias S. Wickleder, Uwe Ruschewitz
      First page: 965
      Abstract: We report on the synthesis and the crystal structure of the solvent-free coordination polymer CoII(2,5-DMT) (1) with 2,5-DMT ≡ 2,5-dimethoxyterephthalate which is isostructural to the already reported MnII and ZnII congeners (C2/c, Z = 4). In contrast, for M = MgII, a MOF with DMF-filled pores is obtained, namely Mg2(2,5-DMT)2(DMF)2 (2) (P1¯, Z = 2). Attempts to remove these solvent molecules to record a gas sorption isotherm did not lead to meaningful results. In a comparative study, the thermal (DSC/TGA) and luminescence properties of all the four compounds were investigated. The compounds of the MII(2,5-DMT) composition show high thermal stability up to more than 300 °C, with the ZnII compound having the lowest decomposition temperature. MII(2,5-DMT) with MII = MnII, ZnII and 2 show a bright luminescence upon blue light irradiation (λ = 405 nm), whereas CoII in 1 quenches the emission. While ZnII in ZnII(2,5-DMT) and MgII in 2 do not significantly influence the (blue) emission and excitation bands compared to the free 2,5-DMT ligand, MnII in MnII(2,5-DMT) shows an additional metal-centred red emission.
      Citation: Chemistry
      PubDate: 2023-04-22
      DOI: 10.3390/chemistry5020065
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 978-986: Mechanosynthesis of
           Diaminobiphenyls-Based Schiff’s Bases as Simple Probes for the
           Naked-Eye Detection of Cyanide Ion

    • Authors: Wahab K. A. Al-Ithawi, Albert F. Khasanov, Igor S. Kovalev, Igor L. Nikonov, Dmitry S. Kopchuk, Vadim A. Platonov, Sougata Santra, Grigory V. Zyryanov, Brindaban C. Ranu
      First page: 978
      Abstract: Cyanide ions are known to be lethal for insects and mammals and harmful for the environment, and new methods for their selective detection are in high demand. Herein, the mechanosynthesis of simple Schiff’s bases-based probes S1–S3 for visual detection of CN− anion is reported. These probes were obtained by means of a reaction between isomeric 4,4-, 3,3- and 2,2-diaminobiphenyls and 4-nitrobenzaldehyde under ball milling conditions. The probes showed high selectivity and sensitivity toward CN− anion via a dramatic “yellow-to-dark purple” color change with a detection limit of 26 × 103, 8.7 × 103 and 14 × 103 ppm for S1–S3, respectively. The proposed mechanism of the detection suggests the deprotonation of a proton from an imine moiety, followed by the formation of charge transfer complexes (CTC).
      Citation: Chemistry
      PubDate: 2023-04-25
      DOI: 10.3390/chemistry5020066
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 987-995: Single-Ion Magnetism in a
           Three-Dimensional Thiocyanate-Bridged Dysprosium(III) Framework

    • Authors: Qingyun Wan, Mirosław Arczyński, Masanori Wakizaka, Shraddha Gupta, Nobuto Funakoshi, Masahiro Yamashita
      First page: 987
      Abstract: New three-dimensional (3D) lanthanide framework compounds supported by bridging thiocyanate ligand and K+ cations, K4[Ln(NCS)4(H2O)4](NCS)3(H2O)2(1: Ln = Dy, 2: Ln = Tb, 3: Ln = Gd) have been synthesized. A single-crystal X-ray diffraction study showed that all three compounds were isostructural and crystallized in the I 2/a space group. The K+ ion form 2D layers with thiocyanates which are further linked by [Ln(NCS)4(H2O)4]- complexes and additional thiocyanate ions to generate an interesting 3D framework structure. Compound 1 shows slow magnetic relaxation behavior under a zero direct current (DC) field, indicating that 1 behaves as a single-ion magnet (SIM). As estimated from AC magnetic measurements, the effective energy barrier for spin reversal in 1 was Ueff = 42 cm–1. Slow relaxation of magnetization under a small external DC field was also detected for 2 and 3 at 1.8 K.
      Citation: Chemistry
      PubDate: 2023-04-26
      DOI: 10.3390/chemistry5020067
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 996-1005: A Missing Nuclearity in the
           Co(III)/Ln(III)/2-Pyridyladoxime Chemistry: Tetranuclear Compounds Using
           the “Assisted Self-Assembly” Approach (Ln = Rare Earth Metals)

    • Authors: Zoi G. Lada, Eugenia Katsoulakou, Christina D. Polyzou, Catherine P. Raptopoulou, Vassilis Psycharis
      First page: 996
      Abstract: By employing the HSAB principle and the “assisted self-assembly” approach and using 2-pyridylaldoximate (pao−) as the primary ligand and pivalate (piv−) as the ancillary co-ligand, tetranuclear [CoIII2LnIII2(NO3)4(pao)4(piv)4] complex polynuclear compounds were isolated (Ln = Dy, Gd, Tb, Pr, Y). The structure of the Dy(III) complex was determined via single-crystal X-ray crystallography, revealing a metal topology of two {CoIIIDyIII2} triangles that shared a common DyIII…DyIII edge. Microanalytical, PXRD (for the two first members)d and spectroscopic (IR, EDX) data for all complexes provided strong evidence that the complexes were isostructural. The nuclearity and metal topology of the crystallographically characterized [CoIII2LnIII2(NO3)4(pao)4(piv)4] are new in the previously investigated CoIII/LnIII/pao− chemistry emphasizing utility of the “assisted self-assembly” approach.
      Citation: Chemistry
      PubDate: 2023-04-27
      DOI: 10.3390/chemistry5020068
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1006-1027: Divalent Europium, NIR and Variable
           Emission of Trivalent Tm, Ho, Pr, Er, Nd, and Ce in 3D Frameworks and 2D
           Networks of Ln–Pyridylpyrazolates

    • Authors: Heba Youssef, Jonathan Becker, Clemens Pietzonka, Ilya V. Taydakov, Florian Kraus, Klaus Müller-Buschbaum
      First page: 1006
      Abstract: The redox reactions of various lanthanide metals with 3-(4-pyridyl)pyrazole (4-PyPzH) or 3-(3-pyridyl)pyrazole (3-PyPzH) ligands yield the 2D network 2∞[Eu(4-PyPz)2(Py)2] containing divalent europium, the 3D frameworks 3∞[Ln(4-PyPz)3] and 3∞[Ln(3-PyPz)3] for trivalent cerium, praseodymium, neodymium, holmium, erbium, and thulium as well as 3∞[La(4-PyPz)3], and the 2D networks 2∞[Ln(4-PyPz)3(Py)] for trivalent cerium and thulium and 2∞[Ln2(4-PyPz)6]·Py for trivalent ytterbium and lutetium. The 18 lanthanide coordination polymers were synthesized under solvothermal conditions in pyridine (Py), partly acting as a co-ligand for some networks. The compounds exhibit a variety of luminescence properties, including metal-centered 4f–4f/5d–4f emission in the visible and near-infrared spectral range, metal-to-ligand energy transfer, and ligand-centered fluorescence and phosphorescence. The anionic ligands 3-PyPz− and 4-PyPz− serve as suitable antennas for lanthanide-based luminescence in the visible and near-infrared range through effective sensitization followed by emission through intra–4f transitions of the trivalent thulium, holmium, praseodymium, erbium, and neodymium. 2∞[Ce(4-PyPz)3(Py)], 3∞[Ce(4-PyPz)3], and 3∞[Ce(3-PyPz)3] exhibit strong degrees of reduction in the 5d excited states that differ in intensity compared to the ligand-based emission, resulting in a distinct emission ranging from pink to orange. The direct current magnetic studies show magnetic isolation of the lanthanide centers in the crystal lattice of 3∞[Ln(3-PyPz)3], Ln = Dy, Ho, and Er.
      Citation: Chemistry
      PubDate: 2023-04-28
      DOI: 10.3390/chemistry5020069
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1028-1045: Synthesis, Structures and
           Photophysical Properties of Tetra- and Hexanuclear Zinc Complexes
           Supported by Tridentate Schiff Base Ligands

    • Authors: Tobias Severin, Viktoriia Karabtsova, Martin Börner, Hendrik Weiske, Agnieszka Kuc, Berthold Kersting
      First page: 1028
      Abstract: The synthesis, structure and photophysical properties of two polynuclear zinc complexes, namely [Zn6L2(µ3-OH)2(OAc)8] (1) and [Zn4L4(µ2-OH)2](ClO4)2 (2), supported by tridentate Schiff base ligand 2,6-bis((N-benzyl)iminomethyl)-4-tert-butylphenol (HL) are presented. The synthesized compounds were investigated using ESI-MS, IR, NMR, UV-vis absorption spectroscopy, photoluminescence spectroscopy and single-crystal X-ray crystallography. The hexanuclear neutral complex 1 comprises six-, five- and four-coordinated Zn2+ ions coordinated by O and N atoms from the supporting ligand and OH- and acetate ligands. The Zn2+ ions in complex cation [Zn4L4(µ2-OH)2]2+ of 2 are all five-coordinated. The complexation of ligand HL by Zn2+ ions leads to a six-fold increase in the intensity and a large blue shift of the ligand-based 1(π-π)* emission. Other biologically relevant ions, i.e., Na+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+ and Cu2+, did not give rise to a fluorescence enhancement.
      Citation: Chemistry
      PubDate: 2023-05-02
      DOI: 10.3390/chemistry5020070
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1046-1059: Justus von Liebig

    • Authors: Siegfried Schindler
      First page: 1046
      Abstract: This is a short overview of the life and achievements of Justus von Liebig. Clearly, this can only be an incomplete and somewhat personal view of the author, who has been a professor of inorganic chemistry at Justus Liebig University since 2002. Having already been interested in the work of Liebig for many years, and with a strong connection to the Liebig Museum in Giessen, the author hopes to provide some useful information about this great chemist, one of the founders of modern chemistry. The reader should find many interesting, probably new, facts about Liebig’s major impact on chemistry, agriculture, nutrition, and pharmacology.
      Citation: Chemistry
      PubDate: 2023-05-06
      DOI: 10.3390/chemistry5020071
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1060-1076: Surface Functionalization of Calcium
           Phosphate Nanoparticles via Click Chemistry: Covalent Attachment of
           Proteins and Ultrasmall Gold Nanoparticles

    • Authors: Kathrin Kostka, Matthias Epple
      First page: 1060
      Abstract: Calcium phosphate nanoparticles (60 nm) were stabilized with either polyethyleneimine (PEI; polycationic electrolyte) or carboxymethylcellulose (CMC; polyanionic electrolyte). Next, a silica shell was added and terminated with either azide or alkyne groups via siloxane coupling chemistry. The particles were covalently functionalized by copper-catalyzed azide-alkyne cycloaddition (CuAAC; click chemistry) with proteins or gold nanoparticles that carried the complementary group, i.e., either alkyne or azide. The model proteins hemoglobin and bovine serum albumin (BSA) were attached as well as ultrasmall gold nanoparticles (2 nm). The number of protein molecules and gold nanoparticles attached to each calcium phosphate nanoparticle was quantitatively determined by extensive fluorescent labelling and UV–Vis spectroscopy on positively (PEI) or negatively (CMC) charged calcium phosphate nanoparticles, respectively. Depending on the cargo and the nanoparticle charge, this number was in the range of several hundreds to thousands. The functionalized calcium phosphate particles were well dispersible in water as shown by dynamic light scattering and internally amorphous as shown by X-ray powder diffraction. They were easily taken up by HeLa cells and not cytotoxic. This demonstrates that the covalent surface functionalization of calcium phosphate nanoparticles is a versatile method to create transporters with firmly attached cargo molecules into cells.
      Citation: Chemistry
      PubDate: 2023-05-07
      DOI: 10.3390/chemistry5020072
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1077-1088: A Simple and Effective Protocol for
           the Pechmann Reaction to Obtain 4-Methylcoumarin Derivatives Using a
           High-Speed Mixer Ball Mill Process

    • Authors: Silvia J. Becerra-Anaya, Diego R. Merchán Arenas, Vladimir V. Kouznetsov
      First page: 1077
      Abstract: We hereby report a simple and efficient method for the preparation of 4-methylcoumarins series, including Coumarin 120 (7-amino-4-methylcoumarin) from phenols (or naphthols) and ethyl acetoacetate in the presence of 3 mol% InCl3. Coumarins were obtained in good yields (52–92%) through Pechmann condensation, under a rapid and environmentally friendly protocol using a high-speed ball mill mixer at room temperature, with short reaction times, under solvent-free conditions.
      Citation: Chemistry
      PubDate: 2023-05-08
      DOI: 10.3390/chemistry5020073
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1089-1100: Exploiting Supramolecular Synthons in
           Cocrystals of Two Racetams with 4-Hydroxybenzoic Acid and
           4-Hydroxybenzamide Coformers

    • Authors: Jason Marquez, Egor Novikov, Sergei Rigin, Marina S. Fonari, Raúl Castañeda, Tatiana Kornilova, Tatiana V. Timofeeva
      First page: 1089
      Abstract: Structures of three cocrystals of nootropic racetams were studied. They included two cocrystals of phenylpiracetam (PPA) with 4-hydroxybenzoic acid (HBA) with different stoichiometries, PPA·HBA and PPA·2HBA, and cocrystal of 2-(4-phenyl-2-oxopyrrolidin-1-yl)-N’-isopropylideneacetohydrazide (PPAH) with 4-hydroxybenzamide (HBD), PPAH·HBD·(acetone solvate). X-ray study of the pure forms of PPA and PPAH was also carried out to identify variations of molecular synthons under the influence of conformers. The cocrystal structures revealed the diversity of supramolecular synthons namely, amide-amide, amide-acid, acid-acid, and hydroxyl-hydroxyl; however, very similar molecular chains were found in PPA and PPA·2HBA, and similar molecular dimers in PPAH and PPAH·HBD. In addition, conformational molecular diversity was observed as disorder in PPA·2HBA as it was observed earlier for rac-PPA that allows for the consideration that cocrystal as an example of partial solid solution. Quantum chemical calculations of PPA and PPAH conformers demonstrated that for most conformers, energy differences do not exceed 2 kcal/mol that suggests the influence of packing conditions (in this case R- and S-enantiomers intend to occupy the same molecular position in crystal) on molecular conformation.
      Citation: Chemistry
      PubDate: 2023-05-08
      DOI: 10.3390/chemistry5020074
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1101-1112: Probing Low-Temperature OCM
           Performance over a Dual-Domain Catalyst Bed

    • Authors: Baoting Huang, Jin Wang, Dina Shpasser, Oz M. Gazit
      First page: 1101
      Abstract: The Mn-Na2WO4/SiO2 catalyst is regarded as the most promising catalyst for the oxidative coupling of methane (OCM). Despite its remarkable performance, the Mn-Na2WO4/SiO2 catalyst requires a high reaction temperature (>750 °C) to show significant activity, a temperature regime that simultaneously causes quick deactivation. In the current work, we show that the benefits of this catalyst can be leveraged even at lower reaction temperatures by a using a stacked catalyst bed, which includes also a small amount of 5% La2O3/MgO on-top- of the Mn-Na2WO4/SiO2 catalyst. The simple stacking of the two catalysts provides >7-fold higher activity and ~1.4-fold higher C2 yield at 705 °C compared to Mn-Na2WO4/SiO2 and La2O3/MgO, respectively. We specifically show that the enhanced OCM performance is associated with synergistic interactions between the two catalyst domains and study their origin.
      Citation: Chemistry
      PubDate: 2023-05-08
      DOI: 10.3390/chemistry5020075
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1113-1123: Five Bonds to Carbon through
           Tri-Coordination in Al3C3−/0

    • Authors: Abdul Hamid Malhan, Venkatesan S. Thimmakondu, Krishnan Thirumoorthy
      First page: 1113
      Abstract: Here, five bonds to carbon through tri-coordination are theoretically established in the global minimum energy isomers of Al3C3− anion (1a) and Al3C3 neutral (1n) for the first time. Various isomers of Al3C3−/0 are theoretically identified using density functional theory at the PBE0-D3/def2-TZVP level. Chemical bonding features are thoroughly analyzed for these two isomers (1a and 1n) with different bonding and topological quantum chemical tools, such as adaptive natural density partitioning (AdNDP), Wiberg Bond Indices (WBIs), nucleus-independent chemical shifts (NICS), and atoms in molecules (AIM) analyses. The structure of isomer 1a is planar with C2v symmetry, whereas its neutral counterpart 1n is non-planar with C2 symmetry, in which its terminal aluminum atoms are out of the plane. The central allenic carbon atom of isomers 1a and 1n exhibits tri-coordination and thus makes it a case of five bonds to carbon, which is confirmed through their total bond order as observed in WBI. Both the isomers show σ- and π-aromaticity and are predicted with the NICS and AdNDP analyses. Further, the results of ab initio molecular dynamics simulations reveal their kinetic stability at room temperature; thus, they are experimentally viable systems.
      Citation: Chemistry
      PubDate: 2023-05-09
      DOI: 10.3390/chemistry5020076
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1124-1137: Activated Carbon from Sugarcane
           Bagasse: A Low-Cost Approach towards Cr(VI) Removal from Wastewater

    • Authors: Rana Ahmed, Inga Block, Fabian Otte, Christina Günter, Alysson Duarte-Rodrigues, Peter Hesemann, Amitabh Banerji, Andreas Taubert
      First page: 1124
      Abstract: The potential of pretreated sugarcane bagasse (SCB) as a low-cost and renewable source to yield activated carbon (AC) for chromate CrO42− removal from an aqueous solution has been investigated. Raw sugarcane bagasse was pretreated with H2SO4, H3PO4, HCl, HNO3, KOH, NaOH, or ZnCl2 before carbonization at 700 °C. Only pretreatments with H2SO4 and KOH yield clean AC powders, while the other powders still contain non-carbonaceous components. The point of zero charge for ACs obtained from SCB pretreated with H2SO4 and KOH is 7.71 and 2.62, respectively. Batch equilibrium studies show that the most effective conditions for chromate removal are a low pH (i.e., below 3) where >96% of the chromate is removed from the aqueous solution.
      Citation: Chemistry
      PubDate: 2023-05-09
      DOI: 10.3390/chemistry5020077
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1138-1170: Liquid Phase Calorimetric Method as a
           Tool for Acid Strength Measurements and Application to a Variety of
           Sustainable Catalysts

    • Authors: Deborah da Silva Valadares, Juliene Oliveira Campos de França, Roberto Chaves Fernandes, Luiz Marcos Dezaneti, Sílvia Cláudia Loureiro Dias, José Alves Dias
      First page: 1138
      Abstract: It has been about 36 years since the first published paper about the calorimetry and adsorption (Cal-Ad) method by Prof. Drago. These separated methods are very old and important characterization tools for different molecules and materials, as recognized in chemistry. The idea of coupling these two techniques arose from the need to have more information about the thermodynamic parameters of a catalyst. The Cal-Ad method provides a measure of the magnitude (Ki), strength (−∆Hi), and quantity (ni) of sites present in a catalyst. The original idea is based on the application of the donor-acceptor concept using the Electrostatic Covalent Model, ECW in the areas of catalysis and material chemistry. Particularly, enthalpy measurements of acidity are directly related to the activity of various catalysts in a variety of reactions. Currently, more than twenty-five catalysts have been carefully characterized by this method in addition to spectroscopic and other thermal methods. Thus, this review seeks to present the fundamentals of the method and show different applications of the characterized catalysts for a variety of reactions in order to use these data as an alternative to choose a catalyst for an acid-dependent type reaction.
      Citation: Chemistry
      PubDate: 2023-05-09
      DOI: 10.3390/chemistry5020078
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1171-1189: Platform Chemicals from Ethylene
           Glycol and Isobutene: Thermodynamics “Pays” for Biomass
           Valorisation and Acquires “Cashback”

    • Authors: Sergey P. Verevkin, Aleksandra A. Zhabina
      First page: 1171
      Abstract: Ethylene glycol (EG) produced from biomass is a promising candidate for several new applications. In this paper, EG derivatives such as mono- and di-tert-butyl ethers are considered. However, accurate thermodynamic data are essential to optimise the technology of the direct tert-butyl ether EG synthesis reaction or reverse process isobutene release. The aim of this work is to measure the vapour pressures and combustion energies for these ethers and determine the vaporisation enthalpies and enthalpies of formation from these measurements. Methods based on the First and Second Law of Thermodynamics were combined to discover the reliable thermodynamics of ether synthesis reactions. The thermochemical data for ethylene glycol tert-butyl ethers were validated using structure–property correlations and quantum chemical calculations. The literature results of the equilibrium study of alkylation of EG with isobutene were evaluated and the thermodynamic functions of ethylene glycol tert-butyl ethers were derived. The energetics of alkylation determined according to the “First Law” and the “Second Law” methods agree very well. Some interesting aspects related to the entropy of ethylene glycol tert-butyl ethers were also revealed and discussed.
      Citation: Chemistry
      PubDate: 2023-05-09
      DOI: 10.3390/chemistry5020079
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1190-1202: Tweaking of Peripheral Moieties in

    • Authors: Soumya Patra, Nimisha A. Mavlankar, Lakshminarayan Ramesan, Ashmeet Singh, Asish Pal
      First page: 1190
      Abstract: The de novo design and synthesis of peptide-based biocatalysts that can mimic the activity of natural enzymes is an exciting field with unique opportunities and challenges. In a natural enzyme, the active site is composed of an assembly of different amino acid residues, often coordinated with a metal ion. A metalloenzyme’s catalytic activity results from the dynamic and concerted interplay of various interactions among the residues and metal ions. Aiming to mimic such enzymes, simple peptide fragments, drawing structural inspiration from natural enzymes, can be utilized as a model. In our effort to mimic a metal-containing hydrolase, we designed peptide amphiphiles (PA) 1 and 2 with a terminal histidine having amide and acid functionalities, respectively, at its C-terminal, imparting differential ability to coordinate with Zn and Cu ions. The PAs demonstrate remarkable self-assembly behavior forming excellent nanofibers. Upon coordination with metal ions, depending on the coordination site the nanofibers become rigidified or weakened. Rheological studies revealed excellent mechanical properties of the hydrogels formed by the PAs and the PA–metal co-assemblies. Using such co-assemblies, we mimic hydrolase activity against a p-nitrophenyl acetate (p-NPA) substrate. Michaelis–Menten’s enzyme kinetic parameters indicated superior catalytic activity of 2 with Zn amongst all the assemblies.
      Citation: Chemistry
      PubDate: 2023-05-10
      DOI: 10.3390/chemistry5020080
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1203-1219: A Pathway for Aldol Additions
           Catalyzed by l-Hydroxyproline-Peptides via a β-Hydroxyketone
           Hemiaminal Intermediate

    • Authors: Lo’ay Ahmed Al-Momani, Heinrich Lang, Steffen Lüdeke
      First page: 1203
      Abstract: While the use of l-proline-derived peptides has been proven similarly successful with respect to enantioselectivity, the physico-chemical and conformational properties of these organocatalysts are not fully compatible with transition state and intermediate structures previously suggested for l-proline catalysis. l-Proline or l-4-hydroxyproline catalysis is assumed to involve proton transfers mediated by the carboxylic acid group, whereas a similar mechanism is unlikely for peptides, which lack a proton donor. Herein, we prepared an array of hydroxyproline-based dipeptides through amide coupling of Boc-protected cis- or trans-4-l-hydroxyproline (cis- or trans-4-Hyp) to benzylated glycine (Gly-OBn) and l-valine (l-Val-OBn) and used these dipeptides as catalysts for a model aldol reaction. Despite the lack of a proton donor in the catalytic site, we observed good stereoselectivities for the R-configured aldol product both with dipeptides formed from cis- or trans-4-Hyp at moderate conversions after 24 h. To explain this conundrum, we modeled reaction cycles for aldol additions in the presence of cis-4-Hyp, trans-4-Hyp, and cis- and trans-configured 4-Hyp-peptides as catalysts by calculation of free energies of conformers of intermediates and transition states at the density functional theory level (B3LYP/6-31G(d), DMSO PCM as solvent model). While a catalytic cycle as previously suggested with l-proline is also plausible for cis- or trans-4-Hyp, with the peptides, the energy barrier of the first reaction step would be too high to allow conversions at room temperature. Calculations on modeled transition states suggest an alternative pathway that would explain the experimental results: here, the catalytic cycle is entered by the acetone self-adduct 4-hydroxy-4-methylpentan-2-one, which forms spontaneously to a small extent in the presence of a base, leading to considerably reduced calculated free energy levels of transition states of reaction steps that are considered rate-determining.
      Citation: Chemistry
      PubDate: 2023-05-10
      DOI: 10.3390/chemistry5020081
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1220-1232: Selective Fluorimetric Detection of
           Pyrimidine Nucleotides in Neutral Aqueous Solution with a
           Styrylpyridine-Based Cyclophane

    • Authors: Julika Schlosser, Julian F. M. Hebborn, Daria V. Berdnikova, Heiko Ihmels
      First page: 1220
      Abstract: A styrylpyridine-containing cyclophane with diethylenetriamine linkers is presented as a host system whose association with representative nucleotides was examined with photometric and fluorimetric titrations. The spectrometric titrations revealed the formation of 1:1 complexes with log Kb values in the range of 2.3–3.2 for pyrimidine nucleotides TMP (thymidine monophosphate), TTP (thymidine triphosphate) and CMP (cytidine monophosphate) and 3.8–5.0 for purine nucleotides AMP (adenosine monophosphate), ATP (adenosine triphosphate), and dGMP (deoxyguanosine monophosphate). Notably, in a neutral buffer solution, the fluorimetric response to the complex formation depends on the type of nucleotide. Hence, quenching of the already weak fluorescence was observed with the purine bases, whereas the association of the cyclophane with pyrimidine bases TMP, TTP, and CMP resulted in a significant fluorescence light-up effect. Thus, it was demonstrated that the styrylpyridine unit is a useful and complementary fluorophore for the development of selective nucleotide-targeting fluorescent probes based on alkylamine-linked cyclophanes.
      Citation: Chemistry
      PubDate: 2023-05-11
      DOI: 10.3390/chemistry5020082
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1233-1242: Short I⋯O Interactions in the
           Crystal Structures of Two 2-Iodo-Phenyl Methyl-Amides as Substrates for
           Radical Translocation Reactions

    • Authors: Ahtsham Ishaq, John M. D. Storey, William T. A. Harrison
      First page: 1233
      Abstract: Radical translocation reactions are finding various uses in organic synthesis, in particular the stereospecific formation of complex natural products. In this work, the syntheses and single-crystal structures of two substituted 2-iodo-phenyl methyl-amides are reported, namely cyclo-propane carboxylic acid (2-iodo-phenyl)-methyl-amide, C11H12INO (1), and cyclo-heptane carboxylic acid (2-iodo-phenyl)-methyl-amide, C15H20INO (2). In each case, the methyl-amide group has a syn conformation, and this grouping is perpendicular to the plane of the benzene ring: these solid-state conformations appear to be well setup to allow an intramolecular hydrogen atom transfer to take place as part of a radical translocation reaction. Short intermolecular I⋯O halogen bonds occur in each crystal structure, leading to [010] chains in 1 [I⋯O = 3.012 (2) Å] and isolated dimers in 2 [I⋯O = 3.024 (4) and 3.057 (4) Å]. The intermolecular interactions are further quantified by Hirshfeld surface analyses.
      Citation: Chemistry
      PubDate: 2023-05-12
      DOI: 10.3390/chemistry5020083
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1243-1255: Modification of the Bridging Unit in
           Luminescent Pt(II) Complexes Bearing C^N*N and C^N*N^C Ligands

    • Authors: Stefan Buss, María Victoria Cappellari, Alexander Hepp, Jutta Kösters, Cristian A. Strassert
      First page: 1243
      Abstract: In this work, we explored the synthesis and characterization of Pt(II) complexes bearing different tri- and tetradentate luminophores acting as C^N*N- and C^N*N^C-chelators. Thus, we investigated diverse substitution patterns in order to improve their processability and assessed the effects of structural variations on their excited state properties. Hence, a detailed analysis of the different synthetic pathways is presented; the photophysical properties were studied by using steady-state and time-resolved photoluminescence spectroscopy. We determined the absorption and emission spectra, the photoluminescence efficiencies, and the excited state lifetimes of the complexes in fluid solutions at room temperature and frozen glassy matrices at 77 K. Finally, a structure–property relationship was established, showing that the decoration of the bridging unit on the tridentate luminophores only marginally affects the excited state properties, whereas the double cyclometallation related to the tetradentate chelator prolongs the excited state lifetime and increases the photoluminescence quantum yield.
      Citation: Chemistry
      PubDate: 2023-05-15
      DOI: 10.3390/chemistry5020084
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1256-1270: Investigation of the Properties of
           Mo/ZSM-5 Catalysts Based on Zeolites with Microporous and
           Micro–Mesoporous Structures

    • Authors: Andrey A. Stepanov, Ludmila L. Korobitsyna, Alexander V. Vosmerikov
      First page: 1256
      Abstract: The dehydroaromatization of methane (MDA) is of great interest as a promising process for processing natural and associated petroleum gases, the main component of which is methane. The rapid loss of catalyst activity because of coke formation hinders the introduction of the DHA methane process into the industry. Therefore, the aim of this research was to find ways to improve Mo/ZSM-5 catalysts for MDA. The paper presents the results of the synthesis of high-silica zeolites of the ZSM-5 type with microporous and micro–mesoporous structures, the preparation of Mo/ZSM-5 catalysts based on them, and the study of the physicochemical and catalytic properties of the obtained samples during the non-oxidative conversion of methane into aromatic hydrocarbons. Zeolite catalysts were investigated using IR spectroscopy, X-ray diffraction, TPD-NH3, SEM, HR-TEM, and N2 adsorption. It was found that the addition of carbon black in the stage of the synthesis of zeolite type ZSM-5 did not lead to structural changes, and the obtained samples had a crystallinity degree equal to 100%. The creation of the micro–mesoporous structure in Mo/ZSM-5 catalysts led to an increase in their activity and stability in the process of methane dehydroaromatization. The highest conversion of methane was observed on a 4.0%Mo/ZSM-5 catalyst prepared based on zeolite synthesized using 1.0% carbon black and was 13.0% after 20 min of reaction, while the benzene yield reached 7.0%. It was shown using HR-TEM that a more uniform distribution of the active metal component was observed in a zeolite catalyst with a micro–mesoporous structure than in a microporous zeolite.
      Citation: Chemistry
      PubDate: 2023-05-17
      DOI: 10.3390/chemistry5020085
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1271-1287: Improved Synthesis and Coordination
           Behavior of 1H-1,2,3-Triazole-4,5-dithiolates (tazdt2−) with NiII,
           PdII, PtII and CoIII

    • Authors: Nils Pardemann, Alexander Villinger, Wolfram W. Seidel
      First page: 1271
      Abstract: A new synthetic route to 1H-1,2,3-triazole-4,5-dithiols (tazdtH2) as ligands for the coordination of NiII, PdII, PtII and CoIII via the dithiolate unit is presented. Different N-protective groups were introduced with the corresponding azide via a click-like copper-catalyzed azide-alkyne [3 + 2] cycloaddition (CuAAC) and fully characterized by NMR spectroscopy. Possible isomers were isolated and an alternative synthetic route was investigated and discussed. After removal of the benzyl protective groups on sulfur by in situ-generated sodium naphthalide, complexes at the [(dppe)M] (M = Ni, Pd, Pt), [(PPh3)2Pt] and [(η5-C5H5)Co] moieties were prepared and structurally characterized by XRD analysis. In this process, the by-products 11 and 12 as monothiolate derivatives were isolated and structurally characterized as well. With regioselective coordination via the dithiolate unit, the electronic influence of different metals or protective groups at N was investigated and compared spectroscopically by means of UV/Vis spectroscopy and cyclic voltammetry. Complex [(η5-C5H5)Co(5c)] (10), is subject to a dimerization equilibrium, which was investigated by temperature-dependent NMR and UV/Vis spectroscopy (solution and solid-state). The thermodynamic parameters of the monomer/dimer equilibrium were derived.
      Citation: Chemistry
      PubDate: 2023-05-17
      DOI: 10.3390/chemistry5020086
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1288-1301: On the Redox Equilibrium of TPP/TPPO
           Containing Cu(I) and Cu(II) Complexes

    • Authors: Stephanie L. Faber, Nesrin I. Dilmen, Sabine Becker
      First page: 1288
      Abstract: Copper(II) clusters of the type [CuII4OCl6L4] (L = ligand or solvent) are a well-studied example of inverse coordination compounds. In the past, they have been studied because of their structural, magnetic, and spectroscopic features. They have long been believed to be redox-inactive compounds, but recent findings indicate a complex chemical equilibrium with diverse mononuclear as well as multinuclear copper(I) and copper(II) compounds. Furthermore, depending on the ligand system, such cluster compounds have proven to be versatile catalysts, e.g., in the oxidation of cyclohexane to adipic acid. This report covers a systematic study of the formation of [CuII4OCl6(TPP)4] and [CuII4OCl6(TPPO)4] (TPP = triphenylphosphine, PPh3; TPPO = triphenylphosphine oxide, O=PPh3) as well as the redox equilibrium of these compounds with mononuclear copper(I) and copper(II) complexes such as [CuIICl2(TPPO)2], [{CuIICl2}2(TPPO)2], [{CuIICl2}3(TPPO)2], [{CuII4Cl4}(TPP)4], and [CuICl(TPP)n] (n = 1–3).
      Citation: Chemistry
      PubDate: 2023-05-17
      DOI: 10.3390/chemistry5020087
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1302-1316: Fe Doping Enhances the Peroxidase-Like
           Activity of CuO for Ascorbic Acid Sensing

    • Authors: Boyu Yan, Ying Yang, Yinyun Xie, Jinzhao Li, Kun Li
      First page: 1302
      Abstract: Although significant advances have been witnessed in the application of nanozymes in recent years, exploring new strategies to enhance the enzyme-like activity of nanozymes is of urgent importance. Herein, we investigate the feasibility of accelerating the peroxidase-like reaction rate of CuO nanostructures through Fe doping. The coprecipitation method was used to synthesize Fe-doped CuO (Fe-CuO) nanozymes, and the results indicate that the diversified valence of Fe benefits the redox reaction driven by CuO-based nanozymes. With the improved peroxidase-like activity, the Fe-CuO nanozyme enables the significant chromogenic oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB), facilitating the construction of a visual sensing platform for the sensitive and selective determination of ascorbic acid. Under optimal conditions, the absorbance at 652 nm decreases linearly with the concentration of ascorbic acid in the range of 5–50 μM, with a limit of detection as low as 4.66 μM. This work exemplifies the activity enhancement for peroxidase-mimicking nanozymes with a metal-doping strategy and provides a broad prospect for the design of more high-performance nanozymes for biosensing applications.
      Citation: Chemistry
      PubDate: 2023-05-23
      DOI: 10.3390/chemistry5020088
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1317-1328: Multiple Intramolecular Hydrogen
           Bonding in Large Biomolecules: DFT Calculations and Deuterium Isotope
           Effects on 13C Chemical Shifts as a Tool in Structural Studies

    • Authors: Poul Erik Hansen, Fadhil S. Kamounah
      First page: 1317
      Abstract: Large biomolecules often have multiple intramolecular hydrogen bonds. In the cases where these interact, it requires special tools to disentangle the patterns. Such a tool could be deuterium isotope effects on chemical shifts. The use of theoretical calculations is an indispensable tool in such studies. The present paper illustrates how DFT calculations of chemical shifts and deuterium isotope effects on chemical shifts in combination with measurements of these effects can establish the complex intramolecular hydrogen bond patterns of rifampicin as an example) The structures were calculated using DFT theoretical calculations, performed with the Gaussian 16 software. The geometries were optimized using the B3LYP functional and the Pople basis set 6-31G(d) and the solvent (DMSO) was taken into account in the PCM approach. Besides the 6-31G(d) basis set, the 6-31 G(d,p) and the 6-3111G(d,p) basis sets were also tested. The nuclear shieldings were calculated using the GIAO approach. Deuteriation was simulated by shortening the X-H bond lengths by 0.01 Å.
      Citation: Chemistry
      PubDate: 2023-05-23
      DOI: 10.3390/chemistry5020089
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1329-1343: Using Imidazolium in the Construction
           of Hybrid 2D and 3D Lead Bromide Pseudoperovskites

    • Authors: Gonzalo García-Espejo, Konstantis F. Konidaris, Antonietta Guagliardi, Norberto Masciocchi
      First page: 1329
      Abstract: The field of hybrid organic–inorganic perovskite materials continues to attract the interest of the scientific community due to their fascinating properties and the plethora of promising applications in photovoltaic and optoelectronic devices. To enhance the efficiency and stability of perovskite-based devices, it is essential to discover novel compounds but also to investigate their various physicochemical, structural, and thermal properties. In this work, we report the synthesis and structural characterization of two novel hybrid lead bromide perovskites, combining the imidazolium cation (IMI) with methylammonium (MA) or formamidinium (FA) cations. The isolated polycrystalline powders were studied with X-ray powder diffraction (XPRD) and were formulated as (IMI)(MA)Pb2Br6, a 3D structure consisting of dimers of face-sharing octahedra linked in corner-sharing mode, and (IMI)(FA)PbBr4, a 2D (110) oriented layer structure with zig-zag corner-sharing octahedra. The thermal stability of (IMI)(MA)Pb2Br6 and (IMI)(FA)PbBr4 was investigated with thermogravimetric (TG) and differential scanning calorimetry (DSC) experiments which showed that both compounds are chemically stable (at least) up to 250 °C. Variable-temperature X-ray diffractometric (VT-XRD) studies of (IMI)(FA)PbBr4 highlighted a structural modification occurring above 100 °C, that is a phase transformation from triclinic to orthorhombic, via an elusive monoclinic phase.
      Citation: Chemistry
      PubDate: 2023-05-26
      DOI: 10.3390/chemistry5020090
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1343-1356: Synthesis and Characterization of
           Abasic β-Diol-C-nucleosides

    • Authors: Maria Moccia, Linda Piras, Gea Bellini, Michele Saviano, Mauro F. A. Adamo
      First page: 1343
      Abstract: Modified nucleobases are potentially useful building blocks when containing catalytically active functionalities and could be introduced in chiral tridimensional molecules such as nucleic acids, which creates the premises for the development of novel catalytic species. Herein, we describe the synthesis of a novel β-C-nucleoside bearing a diol group at anomeric position, amenable as a metal ligand or organocatalyst. An abasic ligand was successfully prepared and inserted into a complementary DNA strand.
      Citation: Chemistry
      PubDate: 2023-05-31
      DOI: 10.3390/chemistry5020091
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1357-1368: The Anion Impact on Dimensionality of
           Cadmium(II) Complexes with Nicotinamide

    • Authors: Željka Soldin, Boris-Marko Kukovec, Milica Kovačić, Marijana Đaković, Zora Popović
      First page: 1357
      Abstract: Three novel cadmium(II) coordination compounds, the dimeric [Cd(CH3COO)2(nia)2]2 (1), the polymeric {[Cd(nia)4](ClO4)2}n (2), and the monomeric [Cd(H2O)3(nia)3](ClO4)2·nia (3), were prepared in the reactions of the nicotinamide (pyridine-3-carboxamide, nia) with the corresponding cadmium(II) salts. All prepared compounds were characterized by elemental analyses, FT-IR spectroscopy, TGA/DTA, and single crystal X-ray analysis. The impact of anions (acetate, perchlorate) and solvent used on the dimensionality of cadmium(II) complexes and the cadmium(II) coordination environment was investigated. The bridging capabilities of acetate ions enabled the formation of dimers in the crystal structure of 1. It was shown that the dimensionality of perchlorate complexes depends on the solvent used. The coordination polymer 2 is isolated from an ethanol solution, while monomeric compound 3 was obtained by using a water/ethanol mixture as a solvent. The pentagonal-bipyramidal coordination of cadmium(II) was found in the presence of chelating and bridging acetate ions in 1. In the presence of non-coordinating perchlorate anions in 2 and 3, the coordination geometry of cadmium(II) is found to be octahedral. The supramolecular amide-amide homosynthon R22(8) was preserved in the hydrogen-bonded frameworks of all three compounds.
      Citation: Chemistry
      PubDate: 2023-06-01
      DOI: 10.3390/chemistry5020092
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1369-1377: Palladium-Catalyzed sp3 C–H
           Acetoxylation of α,α-Disubstituted α-Amino Acids

    • Authors: Atsushi Matsumura, Yoshinosuke Usuki, Tetsuya Satoh
      First page: 1369
      Abstract: The sp3 C–H acetoxylation at the β-position of α,α-disubstituted α-amino acids proceeds smoothly under palladium catalysis in the presence of PhI(OAc)2. This reaction provides a straightforward synthetic route to non-natural β-acetoxy-α-amino acids. The reaction of α-aminocyclopropanecarboxylic acid takes place via ring-opening to selectively afford an acyclic γ-acetoxy-α,β-unsaturated amino acid.
      Citation: Chemistry
      PubDate: 2023-06-01
      DOI: 10.3390/chemistry5020093
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1378-1394: Reactivity of Rare-Earth Oxides in
           Anhydrous Imidazolium Acetate Ionic Liquids

    • Authors: Sameera Shah, Tobias Pietsch, Maria Annette Herz, Franziska Jach, Michael Ruck
      First page: 1378
      Abstract: Rare-earth metal sesquioxides (RE2O3) are stable compounds that require high activation energies in solid-state reactions or strong acids for dissolution in aqueous media. Alternatively, dissolution and downstream chemistry of RE2O3 have been achieved with ionic liquids (ILs), but typically with additional water. In contrast, the anhydrous IL 1-butyl-3-methylimidazolium acetate [BMIm][OAc] dissolves RE2O3 for RE = La–Ho and forms homoleptic dinuclear metal complexes that crystallize as [BMIm]2[RE2(OAc)8] salts. Chloride ions promote the dissolution without being included in the compounds. Since the lattice energy of RE2O3 increases with decreasing size of the RE3+ cation, Ho2O3 dissolves very slowly, while the sesquioxides with even smaller cations appear to be inert under the applied conditions. The Sm and Eu complex salts show blue and red photoluminescence and Van Vleck paramagnetism. The proton source for the dissolution is the imidazolium cation. Abstraction of the acidic proton at the C2-atom yields an N-heterocyclic carbene (imidazole-2-ylidene). The IL can be regenerated by subsequent reaction with acetic acid. In the overall process, RE2O3 is dissolved by anhydrous acetic acid, a reaction that does not proceed directly.
      Citation: Chemistry
      PubDate: 2023-06-02
      DOI: 10.3390/chemistry5020094
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1395-1406: Au Single Metal Atom for Carbon
           Dioxide Reduction Reaction

    • Authors: Anna Vidal-López, Sergio Posada-Pérez, Miquel Solà, Albert Poater
      First page: 1395
      Abstract: CO2 is the gas that contributes the most to the greenhouse effect and, therefore, to global warming. One of the greatest challenges facing humanity is the reduction of the concentration of CO2 in the air. Here, we analyze the possible use of Au1@g-C3N4 electrocatalyst to transform CO2 into added-value products. We use density functional theory (DFT) to determine the reaction Gibbs energies for eight electron–proton transfer reaction paths of the electrochemical carbon dioxide reduction reaction (CO2RR) using a single Au atom supported on 2D carbon nitride support. Our simulations classify the Au1@g-C3N4 electrocatalysts as “beyond CO” since their formation is energetically favored, although their strong binding with a Au single atom does not allow the desorption process. DFT calculations revealed that the lowest energy pathway is CO2 (g) → COOH* → CO* → HCO* → HCOH* → CH2OH* → CH2* → CH3* → CH4 (g), where the first hydrogenation of CO to HCO is predicted as the rate-limiting step of the reaction with slightly lower potential than predicted for Cu electrodes, the most effective catalysts for CO2RR. Methane is predicted to be the main reaction product after eight proton–electron transfers (CO2 + 8 H+ + 8e− → CH4 + 2H2O). The generation of formaldehyde is discarded due to the large formation energy of the adsorbed moiety and the production of methanol is slightly less favorable than methane formation. Our computational study helps to identify suitable electrocatalysts for CO2RR by reducing the amount of metal and using stable and low-cost supports.
      Citation: Chemistry
      PubDate: 2023-06-05
      DOI: 10.3390/chemistry5020095
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1407-1418: Suzuki–Miyaura Reaction in the
           Presence of N-Acetylcysteamine Thioesters Enables Rapid Synthesis of
           Biomimetic Polyketide Thioester Surrogates for Biosynthetic Studies

    • Authors: Sebastian Derra, Luca Schlotte, Frank Hahn
      First page: 1407
      Abstract: Biomimetic N-acetylcysteamine thioesters are essential for the study of polyketide synthases, non-ribosomal peptide synthetases and fatty acid synthases. The chemistry for their preparation is, however, limited by their specific functionalization and their susceptibility to undesired side reactions. Here we report a method for the rapid preparation of N-acetylcysteamine (SNAC) 7-hydroxy-2-enethioates, which are suitable for the study of various enzymatic domains of megasynthase enzymes. The method is based on a one-pot sequence of hydroboration and the Suzuki–Miyaura reaction. The optimization of the reaction conditions made it possible to suppress potential side reactions and to introduce the highly functionalized SNAC methacrylate unit in a high yield. The versatility of the sequence was demonstrated by the synthesis of the complex polyketide-SNAC thioesters 12 and 33. Brown crotylation followed by the hydroboration to Suzuki–Miyaura reaction sequence enabled the introduction of the target motif in significantly fewer steps and with a higher overall yield and stereoselectivity than previously described approaches. This is the first report of a transition-metal-catalyzed cross-coupling reaction in the presence of an SNAC thioester.
      Citation: Chemistry
      PubDate: 2023-06-08
      DOI: 10.3390/chemistry5020096
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1419-1453: Synthetic and Structural Chemistry of
           Uranyl-Amidoxime Complexes: Technological Implications

    • Authors: Sokratis T. Tsantis, Maria Iliopoulou, Demetrios I. Tzimopoulos, Spyros P. Perlepes
      First page: 1419
      Abstract: Resource shortage is a major problem in our world. Nuclear energy is a green energy and because of this and its high energy density, it has been attracting more and more attention during the last few decades. Uranium is a valuable nuclear fuel used in the majority of nuclear power plants. More than one thousand times more uranium exists in the oceans, at very low concentrations, than is present in terrestrial ores. As the demand for nuclear power generation increases year-on-year, access to this reserve is of paramount importance for energy security. Water-insoluble polymeric materials functionalized with the amidoxime group are a technically feasible platform for extracting uranium, in the form of {UO2}2+, from seawater, which also contains various concentrations of other competing metal ions, including vanadium (V). An in-depth understanding of the coordination modes and binding strength of the amidoxime group with uranyl and other competing ions is a key parameter for improving extraction efficiency and selectivity. Very limited information on the complexation of {UO2}2+ with amidoximes was available before 2012. However, significant advances have been made during the last decade. This report reviews the solid-state coordination chemistry of the amidoxime group (alone or within ligands with other potential donor sites) with the uranyl ion, while sporadic attention on solution and theoretical studies is also given. Comparative studies with vanadium complexation are also briefly described. Eight different coordination modes of the neutral and singly deprotonated amidoxime groups have been identified in the structures of the uranyl complexes. Particular emphasis is given to describing the reactivity of the open-chain glutardiamidoxime, closed-ring glutarimidedioxime and closed-ring glutarimidoxioxime moieties, which are present as side chains on the sorbents, towards the uranyl moiety. The technological implications of some of the observed coordination modes are outlined. It is believed that X-ray crystallography of small uranyl-amidoxime molecules may help to build an understanding of the interactions of seawater uranyl with amidoxime-functionalized polymers and improve their recovery capacity and selectivity, leading to more efficient extractants. The challenges for scientists working on the structural elucidation of uranyl coordination complexes are also outlined. The review contains six sections and 95 references.
      Citation: Chemistry
      PubDate: 2023-06-13
      DOI: 10.3390/chemistry5020097
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1454-1464: Rolling-Circle-Amplification-Assisted
           DNA Biosensors for Sensitive and Specific Detection of Hypochlorous Acid
           and Myeloperoxidase

    • Authors: Bo Liu, Jia-Yi Ma, Jing Wang, Dong-Xia Wang, An-Na Tang, De-Ming Kong
      First page: 1454
      Abstract: Hypochlorous acid (HClO) is a common reactive oxygen species (ROS), with a high chemical reactivity. Myeloperoxidase (MPO) is an enzyme that catalyzes in vivo redox reactions between H2O2 and Cl− to produce HClO. Abnormal levels of HClO and MPO may lead to oxidative stress, irreversible tissue damage and, thus, serious diseases; they are thus becoming important biomarkers and therapeutic targets. In this work, using HClO-induced site-specific cleavage of phosphorothioate-modified DNA to trigger rolling circle amplification (RCA), RCA-assisted biosensors have been developed for the highly sensitive and specific detection of HClO and MPO. Only two DNA oligonucleotides are used in the sensing systems. The powerful signal-amplification capability of RCA endows the sensing systems with a high sensitivity, and the specific fluorescent response of thioflavin T (ThT) to G-quadruplexes in RCA products makes a label-free signal output possible. The proposed biosensors were demonstrated to work well not only for the sensitive and specific quantitation of HClO and MPO with detection limits of 1.67 nM and 0.33 ng/mL, respectively, but also for the screening and inhibitory capacity evaluation of MPO inhibitors, thus holding great promise in disease diagnosis and drug analysis.
      Citation: Chemistry
      PubDate: 2023-06-18
      DOI: 10.3390/chemistry5020098
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 1465-1476: Unraveling the Synthesis of
           SbCl(C3N6H4): A Metal-Melaminate Obtained through Deprotonation of
           Melamine with Antimony(III)Chloride

    • Authors: Elaheh Bayat, Markus Ströbele, Hans-Jürgen Meyer
      First page: 1465
      Abstract: The discovery of melamine by Justus von Liebig was fundamental for the development of several fields of chemistry. The vast majority of compounds with melamine or melamine derivatives appear as adducts. Herein, we focus on the development of novel compounds containing anionic melamine species, namely the melaminates. For this purpose, we analyze the reaction of SbCl3 with melamine by differential scanning calorimetry (DSC). The whole study includes the synthesis and characterization of three antimony compounds that are obtained during the deprotonation process of melamine to melaminate with the reaction sequence from SbCl4(C9N18H19) (1) via (SbCl4(C6N12H13))2 (2) to SbCl(C3N6H4) (3). Compounds are characterized by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), and infrared spectroscopy (IR). The results give an insight into the mechanism of deprotonation of melamine, with the replacement of one, two, or eventually three hydrogen atoms from the three amino groups of melamine. The structure of (3) suggests that metal melaminates are likely to form supramolecular structures or metal-organic frameworks (MOFs).
      Citation: Chemistry
      PubDate: 2023-06-20
      DOI: 10.3390/chemistry5020099
      Issue No: Vol. 5, No. 2 (2023)
  • Chemistry, Vol. 5, Pages 571-588: Ni-Mg/Al Mixed Oxides Prepared from
           Double Layered Hydroxides as Catalysts for the Conversion of Furfural to
           Tetrahydrofurfuryl Alcohol

    • Authors: Abdulaziz Aldureid, Daniel Montané, Jordi Llorca, Francesc Medina
      First page: 571
      Abstract: Ni-Mg/Al mixed oxide catalysts (Ni2Al, Ni2Mg1Al, and Ni1Mg1Al) obtained from layered double hydroxides (LDHs) were tested on the one-pot production of tetrahydrofurfuryl alcohol (TFA) from furfural (FF). Upon calcination at 400 °C and reduction at 500 °C, the LDHs gave catalysts containing small nickel crystallites (<4 nm) dispersed on mixtures of metal oxides and spinel structures. Complete conversion of FF (>99.5%) was achieved on all the catalysts after 4 h at 190 °C and 5.0 MPa of H2 using 5 wt.% FF in ethanol and a furfural-to-catalyst mass ratio of 7.44 g/g. TFA evolved from the sequential hydrogenation of FF to furfuryl alcohol (FA) to TFA. Competing reaction routes involved decarbonylation of FF to furan (FUR) followed by hydrogenation to tetrahydrofuran (THF) or hydrogenolysis to n-butane (BU) and the hydrogenation of the carbonyl group in FF to form 2-methyl furan (mFUR) and its hydrogenation to 2-methyltetrahydrofuran (mTHF). A third competing route consisted of the nucleophilic addition of FF with ethanol and with FA to form acetals (such as 2-(diethoxymethyl)furan, FDA), which were later converted to difurfuryl ether (DFE) and tetrahydrofurfuryl ethyl ether (TFEE) as final products. Hydrogen pressure favored the production of TFA and diminished the formation of acetals, while temperature reduced the capacity of the catalyst to hydrogenate the furan ring, thus reducing TFA and increasing FA and FUR. An 80% yield to TFA was achieved with the Ni2Mg1Al catalysts after 6 h at 190 °C and 50 bar H2, but a variety of coproducts were present at low concentration. Testing of the catalysts in gas-phase hydrogenation conditions at atmospheric pressure revealed a poorer performance, with FA as the main product.
      Citation: Chemistry
      PubDate: 2023-03-09
      DOI: 10.3390/chemistry5010041
      Issue No: Vol. 5, No. 1 (2023)
  • Chemistry, Vol. 5, Pages 589-601: Selective Styrene Oxidation Catalyzed by
           Phosphate Modified Mesoporous Titanium Silicate

    • Authors: Rupak Chatterjee, Avik Chowdhury, Sudip Bhattacharjee, Rajaram Bal, Asim Bhaumik
      First page: 589
      Abstract: Selective oxidation of organics over an efficient heterogeneous catalyst under mild liquid phase conditions is a very demanding chemical reaction. Herein, we first report the modification of the surface of mesoporous silica MCM-41 material by phosphate for the efficient incorporation of Ti(IV) in the silica framework to obtain highly ordered 2D hexagonal mesoporous material STP-1. STP-1 has been synthesized by using tetraethyl orthosilicate, triethyl phosphate, and titanium isopropoxide as Si, P, and Ti precursors, respectively, in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) under hydrothermal conditions. The observed specific surface area and pore volume of STP-1 were 878 m2g−1 and 0.75 ccg−1, respectively. Mesoporous STP-1 has been thoroughly characterized by XRD, FT-IR, Raman spectroscopy, SEM, and TEM analyses. Titanium incorporation (Ti/Si = 0.006) was confirmed from the EDX analysis. This mesoporous STP-1 was used as a heterogeneous catalyst for the selective oxidation of styrene into benzaldehye in the presence of dilute aqueous H2O2 as an oxidizing agent. Various reaction parameters such as the reaction time, the reaction temperature, and the styrene/H2O2 molar ratio were systematically studied in this article. Under optimized reaction conditions, the selectivity of benzaldehyde could reach up to 93.8% from styrene over STP-1. Further, the importance of both titanium and phosphate in the synthesis of STP-1 for selective styrene oxidation was examined by comparing the catalytic result with only a phosphate-modified mesoporous silica material, and it suggests that both titanium and phosphate synergistically play an important role in the high selectivity of benzaldehyde in the liquid phase oxidation of styrene.
      Citation: Chemistry
      PubDate: 2023-03-10
      DOI: 10.3390/chemistry5010042
      Issue No: Vol. 5, No. 1 (2023)
  • Chemistry, Vol. 5, Pages 602-615: Comparison of Cu-CHA-Zeolites in the
           Hybrid NSR-SCR Catalytic System for NOx Abatement in Mobile Sources

    • Authors: Sergio Molina-Ramírez, Marina Cortés-Reyes, Concepción Herrera, María Ángeles Larrubia, Luis José Alemany
      First page: 602
      Abstract: DeNOx activity in a NSR–SCR hybrid system of two copper-containing chabazite-type zeolitic catalysts was addressed. A Pt-Ba-K/Al2O3 model catalyst was used as the NSR (NOx storage and reduction) catalyst. For the SCR (selective catalytic reduction) system, two Cu-CHA zeolites were synthesized employing a single hydrothermal synthesis method assisted with ultrasound and incorporating Cu in a 2 wt.%, 2Cu-SAPO-34 and 2Cu-SSZ-13. The prepared catalysts were characterized, and the crystallinity, surface area, pore size, HR-TEM and EDX mapping, coordination of Cu ions and acidity were compared. The NH3 storage capacity of the SCR catalysts was 1890 and 837 μmol NH3·gcat−1 for 2Cu-SAPO-34 and 2Cu-SSZ-13, respectively. DeNOx activity was evaluated for the single NSR system and the double-bed NSR–SCR by employing alternating lean (3%O2) and rich (1%H2) cycles, maintaining a concentration of 600 ppm NO, 1.5% H2O and 0.3% CO2 between 200 and 350 °C. The addition of the SCR system downstream of the NSR catalyst significantly improved NOx conversion mainly at low temperature, maintaining the selectivity to N2 above 80% and reaching values above 90% at 250 °C when the 2Cu-SSZ-13 catalyst was located. The total reduction in the production of NH3 and ~2% of N2O was observed when comparing the NSR–SCR configuration with the single NSR catalyst.
      Citation: Chemistry
      PubDate: 2023-03-10
      DOI: 10.3390/chemistry5010043
      Issue No: Vol. 5, No. 1 (2023)
  • Chemistry, Vol. 5, Pages 616-632: Impact of Di- and Poly-Radical
           Characters on the Relative Energy of the Doubly Excited and La States of
           Linear Acenes and Cyclacenes

    • Authors: Yasi Dai, Juan-Carlos Sancho-García, Fabrizia Negri
      First page: 616
      Abstract: Linear and cyclic acenes are polycyclic aromatic hydrocarbons that can be viewed as building blocks of graphene nanoribbons and carbon nanotubes, respectively. While short linear acenes demonstrated remarkable efficiency in several optoelectronic applications, the longer members are unstable and difficult to synthesize as their cyclic counterparts. Recent progress in on-surface synthesis, a powerful tool to prepare highly reactive species, opens promising perspectives and motivates the computational investigations of these potentially functional molecules. Owing to their di- and poly-radical character, low-lying excited states dominated by doubly excited configurations are expected to become more important for longer members of both linear and cyclic molecules. In this work, we investigate the lowest-lying La and the doubly excited (DE) state of linear acenes and cyclacenes, with different computational approaches, to assess the influence of the di-/poly-radical characters (increasing with the molecular dimensions) on their relative order. We show that DFT/MRCI calculations correctly reproduce the crossing of the two states for longer linear acenes, while TDUDFT calculations fail to predict the correct excitation energy trend of the DE state. The study suggests a similarity in the excited electronic state pattern of long linear and cyclic acenes leading ultimately to a lowest lying dark DE state for both.
      Citation: Chemistry
      PubDate: 2023-03-11
      DOI: 10.3390/chemistry5010044
      Issue No: Vol. 5, No. 1 (2023)
  • Chemistry, Vol. 5, Pages 633-645: MgAl-NO3 LDH: Adsorption Isotherms and
           Multivariate Optimization for Cr(VI) Removal

    • Authors: Anna Maria Cardinale, Cristina Carbone, Simone Molinari, Gabriella Salviulo, Francisco Ardini
      First page: 633
      Abstract: Within the framework of the various strategies studied for the abatement of polluting agents in water, both from anthropogenic and natural origins, adsorption processes are among the most widespread techniques. In this context, Layered Double Hydroxides (LDHs) play a fundamental role. In this study, a Mg–Al LDH (nitrate intercalated, Mg/Al = 2) was prepared to be used as an anion exchanger for Cr(VI)-removal purposes from water. The LDH was synthesized through a coprecipitation reaction, followed by an aging process under heating. The compound was characterized by means of inductively coupled plasma–atomic emission spectroscopy (ICP-AES), X-ray powder diffraction (XRPD), field-emission scanning electron microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FT-IR). Regarding LDH adsorption capacity, with respect to Cr(VI), the adsorption isotherms and reaction kinetic were studied, and the adsorption process was well described by the Langmuir model. A central composite design was used for the multivariate optimization of the working parameters. The maximum adsorption capacity was estimated to be 30 mg/g.
      Citation: Chemistry
      PubDate: 2023-03-14
      DOI: 10.3390/chemistry5010045
      Issue No: Vol. 5, No. 1 (2023)
  • Chemistry, Vol. 5, Pages 646-661: Perspectives on the Structural Design
           and Luminescent Behavior of Liquid Crystalline Materials Based on
           Copper(I) Complexes

    • Authors: Muhammed Alkali, Viorel Cîrcu
      First page: 646
      Abstract: This paper provides insight into the various studies that have been carried out to date on liquid crystalline materials based on copper(I) complexes. Although the study of copper(I) complexes with respect to their liquid crystalline property is quite limited, metallomesogens prepared with different structural components and ligands from groups such as azamacrocycles, alkythiolates, ethers, isocyanides, phenanthroline, Schiff bases, pyrazolates, phosphines, biquinolines, and benzoylthioureas are reported and summarized in this review. A special section is dedicated to the discussion of emission properties of copper(I) metallomesogens.
      Citation: Chemistry
      PubDate: 2023-03-15
      DOI: 10.3390/chemistry5010046
      Issue No: Vol. 5, No. 1 (2023)
  • Chemistry, Vol. 5, Pages 662-690: Cesium Heteropolyacid Salts: Synthesis,
           Characterization and Activity of the Solid and Versatile Heterogeneous

    • Authors: Marcio Jose da Silva, Alana Alves Rodrigues, Neide Paloma Gonçalves Lopes
      First page: 662
      Abstract: Keggin-type heteropolyacid cesium salts have been regarded as potential candidates for heterogeneous catalytic reactions. This review describes the success of Keggin-type heteropolyacids cesium salts (Cs-HPA salts) as efficient catalysts in various synthesis processes. The Cs-HPA catalysts can be synthesized as solid salts through the metathesis of a solution containing precursor HPA and another solution containing soluble Cs salt, which will give Cs-HPA salt as a solid precipitate. Alternatively, they can be also obtained from the commercial precursor HPA. In this review, all the routes to prepare the different cesium salts (i.e., saturated, lacunar, metal-doped) were described. These salts can be used in acid-catalyzed reactions (i.e., esterification, etherification, acetalization, dehydration) or oxidative transformations (oxidative esterification, oxidation, epoxidation). All of these reactions were addressed herein. Aspects related to the synthesis and characterization of these catalyst salts were discussed. This review aims to discuss the most pertinent heterogeneous catalytic systems based on Keggin HPA Cs salts. The focus was to correlate the physicochemical properties of these salts with their catalytic activity. Ultimately, the most recent advances achieved in the applications of these Cs-HPA salts as catalysts in the synthesis of industrial interest compounds were discussed. Cesium heteropoly salts are an alternative to the traditional soluble mineral acids as well as to solid-supported catalysts.
      Citation: Chemistry
      PubDate: 2023-03-21
      DOI: 10.3390/chemistry5010047
      Issue No: Vol. 5, No. 1 (2023)
  • Chemistry, Vol. 5, Pages 691-702: Stimuli-Responsive Designer
           Supramolecular Polymer Gel

    • Authors: M. Douzapau, Srayoshi Roy Chowdhury, Surajit Singh, Olamilekan Joseph Ibukun, Debasish Haldar
      First page: 691
      Abstract: This paper reports a stimuli-responsive designer supramolecular polymer gel in dimethylsulphoxide (DMSO)/water (1:2) based on a dipeptide amphiphile and β-cyclodextrin (β-CD) The dipeptide amphiphile contains caproic acid at the N terminus and methyl ester at the C terminus. From X-ray single crystal diffraction, the amphiphile adopts a kink-like conformation. The amphiphile self-assembled to form a parallel sheet-like structure stabilized by multiple intermolecular hydrogen bonds. Moreover, the parallel sheet-like structure is also stabilized by edge-to-edge π–π stacking interactions. In higher-order packing, it forms a corrugated sheet-like structure stabilized by hydrophobic interactions. The dipeptide amphiphile interacts with β-cyclodextrin and forms gel through supramolecular polymer formation in (DMSO)/water (1:2) by a simple heating-cooling cycle. The sol-to-gel transformation is because of a host–guest complex between compound 1 and β-CD and the formation of supramolecular polymer accompanied by microstructure changes from nanofibers to microrods. The gel is temperature responsive with a Tgel of 70 °C. The supramolecular polymer gel is also responsive to stimuli such aspicric acid and HCl. The extensive spectroscopic studies show that the aromatic hydrophobic side chain of compound 1 forms a host–guest complex with β-CD. These results will be helpful for the design of advanced programable eco-friendly functional materials.
      Citation: Chemistry
      PubDate: 2023-03-22
      DOI: 10.3390/chemistry5010048
      Issue No: Vol. 5, No. 1 (2023)
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