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: 1)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 30)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 9)
ACS Catalysis     Hybrid Journal   (Followers: 51)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 23)
ACS Combinatorial Science     Hybrid Journal   (Followers: 21)
ACS Environmental Au     Open Access   (Followers: 11)
ACS Macro Letters     Hybrid Journal   (Followers: 25)
ACS Materials Letters     Open Access   (Followers: 3)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 41)
ACS Nano     Hybrid Journal   (Followers: 187)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 31)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 8)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 7)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 10)
Adsorption Science & Technology     Open Access   (Followers: 7)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 72)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 3)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 1)
Advanced Science Focus     Free   (Followers: 6)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 2)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 111)
Advances in Chemical Science     Open Access   (Followers: 51)
Advances in Chemistry     Open Access   (Followers: 34)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 15)
Advances in Environmental Chemistry     Open Access   (Followers: 11)
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: 33)
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: 51)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Sample Preparation     Open Access   (Followers: 9)
Advances in Science and Technology     Full-text available via subscription   (Followers: 16)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Chemical Education     Open Access   (Followers: 5)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Aggregate     Open Access   (Followers: 1)
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: 4)
Alchemy : Jurnal Penelitian Kimia     Open Access  
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 44)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 20)
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: 144)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 236)
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: 12)
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: 23)
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  
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: 7)
Autophagy     Hybrid Journal   (Followers: 7)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Hybrid Journal   (Followers: 203)
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: 23)
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: 84)
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: 24)
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  
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Carbohydrate Research     Hybrid Journal   (Followers: 23)
Carbon     Hybrid Journal   (Followers: 65)
Carbon Capture Science & Technology     Open Access  
Carbon Trends     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 9)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 11)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
Chem     Hybrid Journal   (Followers: 1)
Chem Catalysis     Hybrid Journal  
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 7)
Chemical and Engineering News     Free   (Followers: 22)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Hybrid Journal   (Followers: 79)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 26)
Chemical Physics Impact     Full-text available via subscription  
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 178)
Chemical Science     Open Access   (Followers: 41)
Chemical Science International Journal     Open Access  
Chemical Technology     Open Access   (Followers: 75)
Chemical Thermodynamics and Thermal Analysis     Open Access   (Followers: 2)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 40)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 17)
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: 119)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 19)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 18)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 6)
Chemistry Education Review     Open Access   (Followers: 1)
Chemistry in Education     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 42)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 166)
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  
Chemistry–Methods     Open Access   (Followers: 1)
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: 2)
Chromatography Research International     Open Access   (Followers: 4)
Ciencia     Open Access  
Clay Minerals     Hybrid Journal   (Followers: 8)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 6)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
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: 6)
Comptes Rendus : Chimie     Open Access  
Comptes Rendus : Physique     Open Access   (Followers: 3)

        1 2 3 4 | Last

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Chemistry
Number of Followers: 0  

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ISSN (Online) 2624-8549
Published by MDPI Homepage  [84 journals]
  • Chemistry, Vol. 4, Pages 630-646: hERG Blockade Prediction by Combining
           Site Identification by Ligand Competitive Saturation and Physicochemical
           Properties

    • Authors: Himanshu Goel, Wenbo Yu, Alexander D. MacKerell
      First page: 630
      Abstract: The human ether-a-go-go-related gene (hERG) potassium channel is a well-known contributor to drug-induced cardiotoxicity and therefore is an extremely important target when performing safety assessments of drug candidates. Ligand-based approaches in connection with quantitative structure active relationships (QSAR) analyses have been developed to predict hERG toxicity. The availability of the recent published cryogenic electron microscopy (cryo-EM) structure for the hERG channel opened the prospect of using structure-based simulation and docking approaches for hERG drug liability predictions. In recent times, the idea of combining structure- and ligand-based approaches for modeling hERG drug liability has gained momentum offering improvements in predictability when compared to ligand-based QSAR practices alone. The present article demonstrates uniting the structure-based SILCS (site-identification by ligand competitive saturation) approach in conjunction with physicochemical properties to develop predictive models for hERG blockade. This combination leads to improved model predictability based on Pearson’s R and percent correct (represents rank-ordering of ligands) metric for different validation sets of hERG blockers involving a diverse chemical scaffold and wide range of pIC50 values. The inclusion of the SILCS structure-based approach allows determination of the hERG region to which compounds bind and the contribution of different chemical moieties in the compounds to the blockade, thereby facilitating the rational ligand design to minimize hERG liability.
      Citation: Chemistry
      PubDate: 2022-06-21
      DOI: 10.3390/chemistry4030045
      Issue No: Vol. 4, No. 3 (2022)
       
  • Chemistry, Vol. 4, Pages 647-654: Growing Gold Nanostars on SiO2
           Nanoparticles: Easily Accessible, NIR Active Core–Shell
           Nanostructures from PVP/DMF Reduction

    • Authors: Laura C. Straub, John A. Capobianco, Mathias S. Wickleder
      First page: 647
      Abstract: A new synthesis strategy towards gold-coated silica nanoparticles is presented. The method provides an efficient, reliable and facile-coating process of well-defined star-shaped shell structures, characterized by UV-Vis, TEM, PXRD, DLS and zeta-potential measurements. A marked red shift of the Au-based plasmonic band to the region of the first biological window is observed offering great potential for future research of biological applications.
      Citation: Chemistry
      PubDate: 2022-06-21
      DOI: 10.3390/chemistry4030046
      Issue No: Vol. 4, No. 3 (2022)
       
  • Chemistry, Vol. 4, Pages 655-668: Piperine Derivatives Enhance Fusion and
           Axonal Transport of Mitochondria by Activating Mitofusins

    • Authors: Lihong Zhang, Xiawei Dang, Antonietta Franco, Haiyang Zhao, Gerald W. Dorn
      First page: 655
      Abstract: Piperine (1-piperoylpiperidine) is the major pungent component of black pepper (Piper nigrum) and exhibits a spectrum of pharmacological activities. The molecular bases for many of piperine’s biological effects are incompletely defined. We noted that the chemical structure of piperine generally conforms to a pharmacophore model for small bioactive molecules that activate mitofusin (MFN)-mediated mitochondrial fusion. Piperine, but not its isomer chavicine, stimulated mitochondrial fusion in MFN-deficient cells with EC50 of ~8 nM. We synthesized piperine analogs having structural features predicted to optimize mitofusin activation and defined structure-activity relationships (SAR) in live-cell mitochondrial elongation assays. When optimal spacing was maintained between amide and aromatic groups the derivatives were potent mitofusin activators. Compared to the prototype phenylhexanamide mitofusin activator, 2, novel molecules containing the piperidine structure of piperine exhibited markedly enhanced passive membrane permeability with no loss of fusogenic potency. Lead compounds 5 and 8 enhanced mitochondrial motility in cultured murine Charcot-Marie-Tooth disease type 2A (CMT2A) neurons, but only 8 improved mitochondrial transport in sciatic nerve axons of CMT2A mice. Piperine analogs represent a new chemical class of mitofusin activators with potential pharmaceutical advantages.
      Citation: Chemistry
      PubDate: 2022-06-23
      DOI: 10.3390/chemistry4030047
      Issue No: Vol. 4, No. 3 (2022)
       
  • Chemistry, Vol. 4, Pages 216-258: Recent Advances in Influenza, HIV and
           SARS-CoV-2 Infection Prevention and Drug Treatment—The Need for
           Precision Medicine

    • Authors: Tamás Kálai, Judit Erzsébet Pongrácz, Péter Mátyus
      First page: 216
      Abstract: Viruses, and in particular, RNA viruses, dominate the WHO’s current list of ten global health threats. Of these, we review the widespread and most common HIV, influenza virus, and SARS-CoV-2 infections, as well as their possible prevention by vaccination and treatments by pharmacotherapeutic approaches. Beyond the vaccination, we discuss the virus-targeting and host-targeting drugs approved in the last five years, in the case of SARS-CoV-2 in the last one year, as well as new drug candidates and lead molecules that have been published in the same periods. We share our views on vaccination and pharmacotherapy, their mutually reinforcing strategic significance in combating pandemics, and the pros and cons of host and virus-targeted drug therapy. The COVID-19 pandemic has provided evidence of our limited armamentarium to fight emerging viral diseases. Novel broad-spectrum vaccines as well as drugs that could even be applied as prophylactic treatments or in early phases of the viremia, possibly through oral administration, are needed in all three areas. To meet these needs, the use of multi-data-based precision medicine in the practice and innovation of vaccination and drug therapy is inevitable.
      Citation: Chemistry
      PubDate: 2022-03-25
      DOI: 10.3390/chemistry4020019
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 259-269: Initial Coupling and Reaction
           Progression of Directly Deposited Biradical Graphene Nanoribbon Monomers
           on Iodine-Passivated Versus Pristine Ag(111)

    • Authors: Gianluca Galeotti, Massimo Fritton, Matthias Lischka, Sebastian Obermann, Ji Ma, Wolfgang M. Heckl, Xinliang Feng, Markus Lackinger
      First page: 259
      Abstract: The development of widely applicable methods for the synthesis of C-C-bonded nanostructures on inert and insulating surfaces is a challenging yet rewarding milestone in the field of on-surface synthesis. This would enable studies of nearly unperturbed covalent nanostructures with unique electronic properties as graphene nanoribbons (GNR) and π-conjugated 2D polymers. The prevalent Ullmann-type couplings are almost exclusively carried out on metal surfaces to lower the temperature required for initial dehalogenation well below the desorption threshold. To overcome the necessity for the activation of monomers on the target surface, we employ a recently developed Radical Deposition Source (RaDeS) for the direct deposition of radicals onto inert surfaces for subsequent coupling by addition reactions. The radicals are generated en route by indirect deposition of halogenated precursors through a heated reactive tube, where the dehalogenation reaction proceeds. Here, we use the ditopic 6,11-diiodo-1,2,3,4-tetraphenyltriphenylene (DITTP) precursor that afforded chevron-like GNR on Au(111) via the usual two-staged reaction comprised of monomer-coupling into covalent polymers and subsequent formation of an extended GNR by intramolecular cyclodehydrogenation (CDH). As a model system for inert surfaces, we use Ag(111) passivated with a closed monolayer of chemisorbed iodine that behaves in an inert manner with respect to dehalogenation reactions and facilitates the progressive coupling of radicals into extended covalent structures. We deposit the DITTP-derived biradicals onto both iodine-passivated and pristine Ag(111) surfaces. While on the passivated surface, we directly observe the formation of covalent polymers, on pristine Ag(111) organometallic intermediates emerge instead. This has decisive consequences for the further progression of the reaction: heating the organometallic chain directly on Ag(111) results in complete desorption, whereas the covalent polymer on iodine-passivated Ag(111) can be transformed into the GNR. Yet, the respective CDH proceeds directly on Ag(111) after thermal desorption of the iodine passivation. Accordingly, future work is aimed at the further development of approaches for the complete synthesis of GNR on inert surfaces.
      Citation: Chemistry
      PubDate: 2022-03-29
      DOI: 10.3390/chemistry4020020
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 270-271: A Special Issue in Honor of Professor
           Josef Michl

    • Authors: Igor Alabugin, Petr Klán
      First page: 270
      Abstract: This Special Issue of Chemistry is dedicated to Professor Josef Michl [...]
      Citation: Chemistry
      PubDate: 2022-03-30
      DOI: 10.3390/chemistry4020021
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 272-296: Enhanced Photocatalytic Oxidation of RhB
           and MB Using Plasmonic Performance of Ag Deposited on Bi2WO6

    • Authors: Shomaila Khanam, Sanjeeb Kumar Rout
      First page: 272
      Abstract: Visible-light-driven heterostructure Ag/Bi2WO6 nanocomposites were prepared using a hydrothermal method followed by the photodeposition of Ag on Bi2WO6. A photocatalyst with a different molar ratio of Ag to Bi2WO6 (1:1, 1:2 and 2:1) was prepared. The catalytic performance of Ag/Bi2WO6 towards the photocatalytic oxidation of rhodamine B (RhB) and methylene blue (MB) was explored. Interestingly, the Ag/Bi2WO6 (1:2) catalyst exhibited superior performance; it oxidized 83% of RhB to Rh-110 and degraded 68% of MB in 90 min. This might be due to the optimum amount of Ag nanoparticles, which supported the rapid generation and transfer of separated charges from Bi2WO6 to Ag through the Schottky barrier. An excess of Ag on Bi2WO6 (1:1 and 2:1) blocked the active sites of the reaction and did not produce the desired result. The introduction of Ag on Bi2WO6 improved the electrical conductivity of the composite and lowered the recombination rate of charge carriers. Our work provides a cost-effective route for constructing high-performance catalysts for the degradation of toxic dyes.
      Citation: Chemistry
      PubDate: 2022-04-06
      DOI: 10.3390/chemistry4020022
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 297-315: Thermal and Catalytic Pyrolysis of Urban
           Plastic Waste: Modified Mordenite and ZSM-5 Zeolites

    • Authors: Taihana Parente Paula, Maria de Fatima Vieira Marques, Mônica Regina da Costa Marques, Michelle Souza Oliveira, Sergio Neves Monteiro
      First page: 297
      Abstract: Zeolites have been successfully applied as catalysts in the pyrolysis of plastics to obtain valuable lower molecular weight hydrocarbon compounds. In the present work, mordenite was directly synthesized and chemically modified from commercial mordenite to increase pore volume. For the first time, the performance of these mordenites was compared with that of an alkali-treated ZSM-5 as catalysts for assisting the pyrolysis of simulated urban plastic waste. The investigated zeolites were: (i) as-supplied synthetic ZSM-5 (ZSM-5/AS); (ii) 0.2 M NaOH treated ZSM-5 (ZSM-5/02); (iii) as-supplied mordenite (MOR/AS); (iv) 0.2 M NaOH treated mordenite (MOR/02); and (v) synthetic lab-developed mordenite (MOR/SD). The modified and synthesized zeolites were individually applied as catalysts in the 700 °C pyrolyzes of combined polyethylene, polypropylene, and polystyrene wastes in a mixture simulating most plastics found in Rio de Janeiro (Brazil) city garbage composition. X-ray diffraction revealed crystallite sizes of all zeolites in a nanometric range from 17 to 43 nm. Textural analysis disclosed the alkali-treated ZSM-5/02 with a superior external surface area, 153 m²/g, and mesopore volume equal to 0.253 cm3/g. Lower values were obtained by MOR/02 (39 m²/g and 0.072 cm3/g). The pyrolysis of the plastic mixture with ZSM-5/02 presented a lower initial degradation temperature, 387 °C, followed by MOR/02, with 417 °C. The ZSM-5/02 catalyst obtained the highest conversion in the pyrolysis of the plastic mixture, totaling 49.2%. However, pyrolysis assisted by the MOR/02 catalyst showed the largest fraction (81.5%) of light hydrocarbons.
      Citation: Chemistry
      PubDate: 2022-04-08
      DOI: 10.3390/chemistry4020023
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 316-328: Wasteless Synthesis and Properties of
           Highly Dispersed MgAl2O4 Based on Product of Thermal Activation of
           Gibbsite

    • Authors: Aleksey V. Zhuzhgov, Vasily Y. Kruglyakov, Tatyana S. Glazneva, Evgeny A. Suprun, Lyubov A. Isupova
      First page: 316
      Abstract: The study showed that the interaction of the product of centrifugal thermal activation of gibbsite with an aqueous solution of magnesium nitrate at a cationic ratio Mg:Al = 1:2 leads to the formation of mixed double hydroxides both under hydrothermal treatment at 150 °C and at room temperature. The subsequent thermal treatment at 550 °C of the product of mild interaction leads to ~90% alumina-magnesia spinel and ~10% MgO, while the treatment of the hydrothermal interaction product leads to ~100% spinel with the stoichiometric composition MgAl2O4. The obtained spinel samples possess a high specific surface area (above 100 m2/g) and a hierarchical pore structure formed by the micron-level particles of different sizes (1–2 and 10–20 μm) consisting of ~70 nm crystallites with ~3 nm pores; the samples differ mostly in the total volume and quantitative ratio of the pores. The samples have Lewis acid sites of moderate strength on the surface, the amount of which is much lower to how it is when compared with a sample prepared by precipitation in that they also differ by quantity from each other as well (503 μmol/g for stoichiometric spinel and 304 μmol/g for sample with admixture of MgO). As the calcination temperature is raised to 850 °C, the acidity decreases—only weak Lewis acid sites are observed, the amount of which is also higher for stoichiometric spinel (161 and 39 μmol/g, respectively). The method proposed for the synthesis of alumina-magnesia systems provides a high dispersion and a much lower surface acidity for the oxides; in addition, it minimizes or completely excludes wash water, in distinction to the precipitation method.
      Citation: Chemistry
      PubDate: 2022-04-11
      DOI: 10.3390/chemistry4020024
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 329-344: Raman Activities of Cyano-Ester
           Quinoidal Oligothiophenes Reveal Their Diradical Character and the
           Proximity of the Low-Lying Double Exciton State

    • Authors: Yasi Dai, Laura Bonometti, José Luis Zafra, Kazuo Takimiya, Juan Casado, Fabrizia Negri
      First page: 329
      Abstract: Quinoidal oligothiophenes have received considerable attention as interesting platforms with remarkable amphoteric redox behavior associated with their diradical character increasing with the conjugation lengths. In this work, we considered a family of quinoidal oligothiophenes bearing cyano-ester terminal groups and characterized them by UV-Vis-NIR absorption and Raman spectroscopy measurements at different excitation wavelengths. The experimental investigation is complemented by quantum-chemical studies to assess the quality of computed density functional theory (DFT) ground state structures and their influence on predicted Raman intensities. In addition, resonance conditions with the optically active HOMO→LUMO transition as well as with the more elusive state dominated by the doubly excited HOMO,HOMO→LUMO,LUMO configuration, are determined with DFT-MRCI calculations and their contributions to Raman activity enhancement are discussed in terms of computed vibrational Huang–Rhys (HR) factors.
      Citation: Chemistry
      PubDate: 2022-04-15
      DOI: 10.3390/chemistry4020025
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 345-369: Green Synthesis of Gold Nanoparticles:
           An Eco-Friendly Approach

    • Authors: Poornima Budime Budime Santhosh, Julia Genova, Hassan Chamati
      First page: 345
      Abstract: By virtue of their unique physicochemical properties, gold nanoparticles (AuNPs) have gained significant interest in a broad range of biomedical applications such as sensors, diagnosis, and therapy. AuNPs are generally synthesized via different conventional physical and chemical methods, which often use harmful chemicals that induce health hazards and pollute the environment. To overcome these issues, green synthesis techniques have evolved as alternative and eco-friendly approaches to the synthesis of environmentally safe and less-expensive nanoparticles using naturally available metabolites from plants and microorganisms such as bacteria, fungi, and algae. This review provides an overview of the advances in the synthesis of AuNPs using different biological resources with examples, and their profound applications in biomedicine. A special focus on the biosynthesis of AuNPs using different medicinal plants and their multifunctional applications in antibacterial, anti-inflammatory, and immune responses are featured. Additionally, the applications of AuNPs in cancer theranostics, including contrast imaging, drug delivery, hyperthermia, and cancer therapeutics, are comprehensively discussed. Moreover, this review will shed light on the importance of the green synthesis approach, and discuss the advantages, challenges, and prospects in this field.
      Citation: Chemistry
      PubDate: 2022-04-25
      DOI: 10.3390/chemistry4020026
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 370-379: Carbon Nanotubes Modified by BiMo Metal
           Oxides for Oxidative Dehydrogenation of 1-Butene to 1,3-Butadiene without
           Steam

    • Authors: Jiao Wu, Yu Liang, Gui Li, Chao Wan
      First page: 370
      Abstract: Oxidative dehydrogenation (ODH) reaction has emerged as a promising route for converting 1-butene to value-added 1,3-butadiene (BD). However, the low BD selectivity of the current catalysts (≤40%) and high steam input are now the challenge of this process. Here, we demonstrate the fabrication BiMo oxides immobilized on carbon nanotubes (BiMo/CNTs), employing the sol–gel method, as a novel catalyst for the ODH of 1-butene without steam in a fixed-bed reactor. The catalytic performances of BiMo/CNTs with different compositions in the absence of steam were investigated. When BiMo/CNTs at a molar ratio of 0.018 were employed in the ODH of 1-butene under reaction conditions of 440 °C, 1-butene/oxygen = 1/0.8, and no steam, the optimal BD yield was achieved as high as 52.2%. Under this reaction condition, the catalyst maintains good stability without steam after 10 h of reaction. This work not only promotes the application of carbon materials in oxidative dehydrogenation reaction, but also accelerates the production of 1,3-butadiene in a more economical way.
      Citation: Chemistry
      PubDate: 2022-04-27
      DOI: 10.3390/chemistry4020027
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 380-392: In Situ FBG Monitoring of a
           Henequen-Epoxy Biocomposite: From Manufacturing to Performance

    • Authors: Mauricio Torres, Ana V. Rentería-Rodríguez, Edgar A. Franco-Urquiza
      First page: 380
      Abstract: This work reports the in situ instrumentation from manufacturing to loading of a henequen fiber woven-bioepoxy composite. Continuous monitoring was performed by means of fiber Bragg gratings (FBG) with the aim of tracking the curing behavior of the biolaminate by vacuum-assisted resin infusion (VARI). The instrumented composite was later tested mechanically under bending. Among the results obtained, micro-deformations were detected as a consequence of curing residual stresses, and when tested, the FBG data had similarity with the strain calculated according to the ASTM D7264/D7264M standard.
      Citation: Chemistry
      PubDate: 2022-04-28
      DOI: 10.3390/chemistry4020028
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 393-404: Assembly of a 3D Cobalt(II)
           Supramolecular Framework and Its Applications in Hydrofunctionalization of
           Ketones and Aldehydes

    • Authors: Guoqi Zhang, Alex Wang, Haisu Zeng, Shengping Zheng, Michelle C. Neary
      First page: 393
      Abstract: A ditopic nitrogen ligand (E)-N′-(pyridin-4-ylmethylene)isonicotinohydrazide (L) containing both divergent pyridyl coordination sites and a hydrogen-bonding hydrazide–hydrazone moiety was synthesized. The Co(NCS)2-mediated self-assembly of L has resulted in the synthesis of a novel 3-dimensional (3D) supramolecular framework (1) that features both coordination and hydrogen bonding interactions. X-ray structural analysis reveals the formation and coordination mode of 1 in the solid state. The rational utilization of coordination bonds and hydrogen bonding interactions is confirmed and responsible for constructing the 3D materials. Catalytic studies using 1 in the presence of an activator are performed for the hydroboration and hydrosilylation reactions of ketones and aldehydes, and the results are compared with previously reported cobalt-based polymeric catalysts.
      Citation: Chemistry
      PubDate: 2022-04-28
      DOI: 10.3390/chemistry4020029
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 405-418: Physicochemical and Functional
           Properties of Okra Leaf Polysaccharides Extracted at Different pHs

    • Authors: Ibukunoluwa Fola Olawuyi, Jong Jin Park, Dongyup Hahn, Won Young Lee
      First page: 405
      Abstract: Different extraction pH values obtain polysaccharides with tailored structures and novel functionalities. This study investigated the influence of different extraction pH values (4.2, 6.8, and 9.2) on the physicochemical compositions and structural and functional properties of okra leaf polysaccharides (OLPs). The extraction yield (2.74–7.34%), molecular weights (68.5–85.4 kDa), total sugar contents (64.87–95.68%), degree of acetylation (18.28–22.88%), and methylation (8.97–15.20%) of OLPs varied significantly (p < 0.05). The monosaccharide composition reflected OLPs as pectic polysaccharides, with varied compositions of galacturonic acid, galactose, rhamnose, and arabinose. However, the differences in their sugar molar ratios, such as their side-chain and backbone chain compositions, greatly affected their functional properties. Additionally, notable differences due to extraction pH were observed in physical properties, thermal stability, and crystallinity. However, FTIR and NMR spectra revealed that extraction pH had negligible effects on the primary structure of OLPs. All OLPs showed non-Newtonian fluid behavior in the aqueous system with different apparent viscosities correlating with their molecular weights. Furthermore, the OLPs fractions stabilized oil-in-water emulsions differently and had distinct radical scavenging activities related to their compositions. This study provides a basis for selecting appropriate extraction pH to prepare OLPs with specific characteristics and applications in food-related disciplines.
      Citation: Chemistry
      PubDate: 2022-04-28
      DOI: 10.3390/chemistry4020030
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 419-430: Characterizing the Properties of
           Anion-Binding Bis(cyclopeptides) with Solvent-Independent Energy
           Increments

    • Authors: Stefan Kubik
      First page: 419
      Abstract: The binding energies of 121 complexes between anions and bis(cyclopeptides) differing in the structure and the number of linking units between the two cyclopeptide rings were analyzed. These Gibbs free energies were obtained in earlier work for different anions, under different conditions, and with different methods. The multiparametric analysis of a subset of 42 binding energies afforded linear relationships that allowed the relatively reliable estimation of the iodide and sulfate affinity of three structurally related bis(cyclopeptides) in water/methanol and water/acetonitrile mixtures at different solvent compositions. Three parameters were required to achieve a satisfactory correlation, namely, the Gibbs free energy of transferring the respective anion from water into the solvent mixture in which complex stability was determined, and the Kamlet–Taft parameters α and β. Based on these relationships, the anion affinities of the other bis(cyclopeptides) were evaluated, giving rise to a set of energy increments that allow quantifying the effects of the linker structure or the nature of the anion on binding affinity relative to the reference system.
      Citation: Chemistry
      PubDate: 2022-05-12
      DOI: 10.3390/chemistry4020031
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 431-446: A Review on the Effects of Organic
           Structure-Directing Agents on the Hydrothermal Synthesis and
           Physicochemical Properties of Zeolites

    • Authors: Zahra Asgar Pour, Khaled O. Sebakhy
      First page: 431
      Abstract: The study on the synthesis of zeolites, including both the development of novel techniques of synthesis and the discovery of new zeolitic frameworks, has a background of several decades. In this context, the application of organic structure-directing agents (SDAs) is one of the key factors having an important role in the formation of porous zeolitic networks as well as the crystallization process of zeolites. There are various elements that are needed to be explored for elucidating the effects of organic SDAs on the final physicochemical properties of zeolites. Although SDAs were firstly used as pore generators in the synthesis of high-silica zeolites, further studies proved their multiple roles during the synthesis of zeolites, such as their influences on the crystallization evolution of zeolite, the size of the crystal and the chemical composition, which is beyond their porogen properties. The aim of this mini review is to present and briefly summarize these features as well as the advances in the synthesis of new SDAs during the last decades.
      Citation: Chemistry
      PubDate: 2022-05-13
      DOI: 10.3390/chemistry4020032
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 447-453: Structures and Bonding in Hexacarbonyl
           Diiron Polyenes: Cycloheptatriene and 1,3,5-Cyclooctatriene

    • Authors: Min Zhang, Guangchao Liang
      First page: 447
      Abstract: Structural preferences of (1,3,5-cyclooctatriene) hexacarbonyl diiron [(C8H10)Fe2(CO)6] and cycloheptatriene hexacarbonyl diiron [(C7H8)Fe2(CO)6] were explored using density functional theory (DFT) computations. DFT computations together with experimental results demonstrated that structure with the [η3, (η1, η2)] mode is the preferred structure in (C8H10)Fe2(CO)6, and the [η3,η3] mode is preferred in (C7H8)Fe2(CO)6. For (C8H10)Fe2(CO)6, the conversion between the structures with [η3, (η1, η2)] mode and the [η3, η3] mode is prevented by the relatively high activation barrier. (C8H10)Fe2(CO)6 is indicated as a fluxional molecule with a Gibbs free energy of activation of 8.5 kcal/mol for its ring flicking process, and an excellent linear correlation (R2 = 0.9909) for the DFT simulated 1H-NMR spectra was obtained. Results provided here will develop the understanding on the structures of other polyene analogs.
      Citation: Chemistry
      PubDate: 2022-05-15
      DOI: 10.3390/chemistry4020033
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 454-479: A Photocatalytic Hydrolysis and
           Degradation of Toxic Dyes by Using Plasmonic Metal–Semiconductor
           Heterostructures: A Review

    • Authors: Shomaila Khanam, Sanjeeb Kumar Rout
      First page: 454
      Abstract: Converting solar energy to chemical energy through a photocatalytic reaction is an efficient technique for obtaining a clean and affordable source of energy. The main problem with solar photocatalysts is the recombination of charge carriers and the large band gap of the photocatalysts. The plasmonic noble metal coupled with a semiconductor can give a unique synergetic effect and has emerged as the leading material for the photocatalytic reaction. The LSPR generation by these kinds of materials has proved to be very efficient in the photocatalytic hydrolysis of the hydrogen-rich compound, photocatalytic water splitting, and photocatalytic degradation of organic dyes. A noble metal coupled with a low bandgap semiconductor result in an ideal photocatalyst. Here, both the noble metal and semiconductor can absorb visible light. They tend to produce an electron–hole pair and prevent the recombination of the generated electron–hole pair, which ultimately reacts with the chemicals in the surrounding area, resulting in an enhanced photocatalytic reaction. The enhanced photocatalytic activity credit could be given to the shared effect of the strong SPR and the effective separation of photogenerated electrons and holes supported by noble metal particles. The study of plasmonic metal nanoparticles onto semiconductors has recently accelerated. It has emerged as a favourable technique to master the constraint of traditional photocatalysts and stimulate photocatalytic activity. This review work focuses on three main objectives: providing a brief explanation of plasmonic dynamics, understanding the synthesis procedure and examining the main features of the plasmonic metal nanostructure that dominate its photocatalytic activity, comparing the reported literature of some plasmonic photocatalysts on the hydrolysis of ammonia borane and dye water treatment, providing a detailed description of the four primary operations of the plasmonic energy transfer, and the study of prospects and future of plasmonic nanostructures.
      Citation: Chemistry
      PubDate: 2022-05-15
      DOI: 10.3390/chemistry4020034
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 480-493: Influence of the Support Composition on
           the Activity of Cobalt Catalysts Supported on Hydrotalcite-Derived Mg-Al
           Mixed Oxides in Ammonia Synthesis

    • Authors: Magdalena Zybert, Hubert Ronduda, Aleksandra Dziewulska, Kamil Sobczak, Andrzej Ostrowski, Wojciech Patkowski, Wioletta Raróg-Pilecka
      First page: 480
      Abstract: Recently, catalysts with hydrotalcites and hydrotalcite-derived compounds have attracted particular interest due to their specific properties, mostly well-developed texture, high thermal stability, and favorable acid–base properties. In this work, we report the investigation of ammonia synthesis on barium-promoted cobalt catalysts supported on hydrotalcite-derived Mg-Al mixed oxides with different Mg/Al molar ratios. The obtained catalysts were characterized using TGA-MS, nitrogen physisorption, XRPD, TEM, STEM-EDX, H2-TPD, CO2-TPD, and tested in ammonia synthesis (470 °C, 6.3 MPa, H2/N2 = 3). The studies revealed that the prepared Mg-Al mixed oxides are good candidates as support materials for Co-based catalysts. However, interestingly, the support composition does not influence the activity of Ba/Co/Mg-Al catalysts. The change in Mg/Al molar ratio in the range of 2–5 did not significantly change the catalyst properties. All the catalysts are characterized by similar textural, structural, and chemisorption properties. The similar density of basic sites on the surface of the studied catalysts was reflected in their comparable performance in ammonia synthesis.
      Citation: Chemistry
      PubDate: 2022-05-17
      DOI: 10.3390/chemistry4020035
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 494-519: Metal–Organic Cages:
           Applications in Organic Reactions

    • Authors: Shangjun Chen, Li-Jun Chen
      First page: 494
      Abstract: Supramolecular metal–organic cages, a class of molecular containers formed via coordination-driven self-assembly, have attracted sustained attention for their applications in catalysis, due to their structural aesthetics and unique properties. Their inherent confined cavity is considered to be analogous to the binding pocket of enzymes, and the facile tunability of building blocks offers a diverse platform for enzyme mimics to promote organic reactions. This minireview covers the recent progress of supramolecular metal–organic coordination cages for boosting organic reactions as reaction vessels or catalysts. The developments in the utilizations of the metal–organic cages for accelerating the organic reactions, improving the selectivity of the reactions are summarized. In addition, recent developments and successes in tandem or cascade reactions promoted by supramolecular metal–organic cages are discussed.
      Citation: Chemistry
      PubDate: 2022-05-18
      DOI: 10.3390/chemistry4020036
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 520-534: Structural Diversity of Lithium
           Oligo-α-Pyridylamides

    • Authors: Arsen Raza, Adele Mucci, Alessio Nicolini, Andrea Cornia
      First page: 520
      Abstract: Lithium oligo-α-pyridylamides are useful intermediates in coordination chemistry. Upon trans-metalation they have afforded a variety of extended metal atom chains (EMACs), which are currently investigated as molecular wires and single-molecule magnets. However, structural information on this class of compounds is scarce. Two trilithium salts of a new, sterically encumbered oligo-α-pyridylamido ligand were isolated in crystalline form and structurally characterized in the solid state and in solution. Lithiation of N2-(trimethylsilyl)-N6-{6-[(trimethylsilyl)amino]pyridin-2-yl}pyridine-2,6-diamine (H3L) with n-BuLi in thf yielded dimeric adduct [Li6L2(thf)6] (1), which was crystallized from n-hexane/thf as 1·C6H14. Crystals of a tetra-thf solvate with formula [Li6L2(thf)4] (2) were also obtained. The compounds feature two twisted L3− ligands exhibiting a cis-cis conformation and whose five nitrogen donors are all engaged in metal coordination. The six Li+ ions per molecule display coordination numbers ranging from 3 to 5. Compound 1·C6H14 was investigated by multinuclear 1D and 2D NMR spectroscopy, including 1H DOSY experiments, which indicated retention of the dimeric structure in benzene-d6 solution. To the best of our knowledge, 1 and 2 are the longest-chain lithium oligo-α-pyridylamides structurally authenticated so far, thereby qualifying as appealing intermediates to access high-nuclearity EMACs by trans-metalation.
      Citation: Chemistry
      PubDate: 2022-05-25
      DOI: 10.3390/chemistry4020037
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 535-547: Self-Assembly of a Rare High Spin
           FeII/PdII Tetradecanuclear Cubic Cage Constructed via the Metalloligand
           Approach

    • Authors: Hyunsung Min, Alexander R. Craze, Takahiro Taira, Matthew J. Wallis, Mohan M. Bhadbhade, Ruoming Tian, Daniel J. Fanna, Richard Wuhrer, Shinya Hayami, Jack K. Clegg, Christopher E. Marjo, Leonard F. Lindoy, Feng Li
      First page: 535
      Abstract: Polynuclear heterobimetallic coordination cages in which different metal cations are connected within a ligand scaffold are known to adopt a variety of polyhedral architectures, many of which display interesting functions. Within the extensive array of coordination cages incorporating Fe(II) centres reported so far, the majority contain low-spin (LS) Fe(II), with high-spin (HS) Fe(II) being less common. Herein, we present the synthesis and characterisation of a new tetradecanuclear heterobimetallic [Fe8Pd6L8](BF4]28 (1) cubic cage utilising the metalloligand approach. Use of the tripodal tris-imidazolimine derivative (2) permitted the formation of the tripodal HS Fe(II) metalloligand [FeL](BF4)2·CH3OH (3) that was subsequently used to form the coordination cage 1. Magnetic and structural analyses gave insight into the manner in which the HS environment of the metalloligand was transferred into the cage architecture along with the structural changes that accompanied its occupancy of the eight corners of the discrete cubic structure.
      Citation: Chemistry
      PubDate: 2022-05-26
      DOI: 10.3390/chemistry4020038
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 548-559: Kinetics of Thermal Decomposition of
           Particulate Samples of MgCO3: Experiments and Models

    • Authors: Francesca Mancarella, Marcella D’Elia, Gaia Micca Longo, Savino Longo, Vincenzo Orofino
      First page: 548
      Abstract: In this work, we study the kinetics of thermal decomposition of MgCO3 in the form of particles of known size. In the experiments, the material is heated to a known temperature in a vacuum oven, and it is characterized, both before and after heating, by infrared spectroscopy and gravimetry. The agreement between the results of the two techniques is excellent. These results are rationalized by means of a model based on Languir’s law, and the comparison with the experiments allows us to estimate the activation energy of the process. The reabsorption of atmospheric water by the oxide is shown spectroscopically, finding that is strongly influenced by the temperature of the process.
      Citation: Chemistry
      PubDate: 2022-05-31
      DOI: 10.3390/chemistry4020039
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 560-575: Copper(II) NHC Catalyst for the
           Formation of Phenol from Arylboronic Acid

    • Authors: Mitu Sharma, Bhupendra Adhikari, Raymond Femi Awoyemi, Amanda M. Perkins, Alison K. Duckworth, Bruno Donnadieu, David O. Wipf, Sean L. Stokes, Joseph P. Emerson
      First page: 560
      Abstract: Arylboronic acids are commonly used in modern organic chemistry to form new C–C and C–heteroatom bonds. These activated organic synthons show reactivity with heteroatoms in a range of substrates under ambient oxidative conditions. This broad reactivity has limited their use in protic, renewable solvents like water, ethanol, and methanol. Here, we report our efforts to study and optimize the activation of arylboronic acids by a copper(II) N-heterocyclic carbene (NHC) complex in aqueous solution and in a range of alcohols to generate phenol and aryl ethers, respectively. The optimized reactivity showcases the ability to make targeted C–O bonds, but also identifies conditions where water and alcohol activation could be limiting for C–C and C–heteroatom bond-forming reactions. This copper(II) complex shows strong reactivity toward arylboronic acid activation in aqueous medium at ambient temperature. The relationship between product formation and temperature and catalyst loading are described. Additionally, the effects of buffer, pH, base, and co-solvent are explored with respect to phenol and ether generation reactions. Characterization of the new copper(II) NCN-pincer complex by X-ray crystallography, HR-MS, cyclic voltammetry, FT-IR and UV-Vis spectral studies is reported.
      Citation: Chemistry
      PubDate: 2022-06-07
      DOI: 10.3390/chemistry4020040
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 576-591: The Dielectric Behavior of Protected
           HKUST-1

    • Authors: Simona Sorbara, Nicola Casati, Valentina Colombo, Filippo Bossola, Piero Macchi
      First page: 576
      Abstract: We investigated the adsorption properties and the dielectric behavior of a very well-known metal-organic framework (MOF), namely Cu3(BTC)2 (known as HKUST-1; BTC = 1,3,5-benzenetricarboxylate), before and after protection with some amines. This treatment has the purpose of reducing the inherent hygroscopic nature of HKUST-1, which is a serious drawback in its application of as low-dielectric-constant (low-κ) material. Moreover, we investigated the structure of HKUST-1 under a strong electric field, confirming the robustness of the framework. Even under dielectric perturbation, the water molecules adsorbed by the MOF remained almost invisible to X-ray diffraction, apart from those directly bound to the metal ions. However, the replacement of H2O with a more visible guest molecule such as CH2Br2 made the cavity that traps the guest more visible. Finally, in this work we demonstrate that impedance spectroscopy is a valuable tool for identifying water sorption in porous materials, providing information that is complementary to that of adsorption isotherms.
      Citation: Chemistry
      PubDate: 2022-06-10
      DOI: 10.3390/chemistry4020041
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 592-602: Conversion Study on the Formation of
           Mechanochemically Synthesized BaTiO3

    • Authors: Gábor Kozma, Kata Lipták, Cora Deák, Andrea Rónavári, Ákos Kukovecz, Zoltán Kónya
      First page: 592
      Abstract: Mechanochemistry is a method that can cover the energy demand of reaction pathways between solid materials. This requires enough energy to maintain the reactions between the starting materials. This is called “high-energy milling”. In our case, a planetary ball mill provided the required energy. Using the Burgio-equation, the required energy is determinable; the energy released during a single impact of a milling ball (Eb), as well as during the whole milling process (Ecum). The aim of this work was the one-step production of BaTiO3 from BaO and TiO2 starting materials. Whereas during mechanochemical reactions it is possible to produce nanoparticles of up to 10 nm, the essence of this study is to develop the preparation of BaTiO3 with a perovskite structure even without subsequent heat treatment, since sintering at high temperatures is associated with a rapid increase in the size of the particles. By describing the synthesis parameters and their energy values (Eb and Ecum), it is possible to transpose experimental conditions, so that in the case of other types of planetary ball mills or grinding vessel made of other materials, the results can be used. In this study, the mechanical treatment was carried out with a Fritsch Pulverisette-6 planetary ball mill and the transformation of the starting materials was investigated by X-ray diffractometric, Raman and Energy-dispersive X-ray spectroscopic, and transmission electron microscopic measurements.
      Citation: Chemistry
      PubDate: 2022-06-15
      DOI: 10.3390/chemistry4020042
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 603-614: Enhancing of CO Uptake in Metal-Organic
           Frameworks by Linker Functionalization: A Multi-Scale Theoretical Study

    • Authors: Charalampos G. Livas, Emmanuel Tylianakis, George E. Froudakis
      First page: 603
      Abstract: In the present work, the interaction strength of Carbon Monoxide (CO) with a set of forty-two, strategically selected, functionalized benzenes was calculated. Our ab initio calculations at the MP2/6-311++G** level of theory reveal that phenyl hydrogen sulfate (-OSO3H) showed the highest interaction with CO (−19.5 kJ/mol), which was approximately three times stronger compared with the unfunctionalized benzene (−5.3 kJ/mol). Moreover, the three top-performing functional groups (-OSO3H, -OPO3H2, -SO3H) were selected to modify the organic linker of IRMOF-8 and test their ability to capture CO at 298 K for a wide pressure range. Our Grand Canonical Monte Carlo (GCMC) simulations showed a significant increase in the CO uptake in the functionalized MOFs compared with the parent IRMOF-8. It is distinctive that for the volumetric uptake, a 60× increase was observed at 1 bar and 2× was observed at 100 bar. The proposed functionalization strategy can be applied for improving the CO uptake performance not only in MOFs but also in various other porous materials.
      Citation: Chemistry
      PubDate: 2022-06-16
      DOI: 10.3390/chemistry4020043
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 615-629: Multicomponent Electrocatalytic
           Selective Approach to Unsymmetrical
           Spiro[furo[3,2-c]pyran-2,5′-pyrimidine] Scaffold under a Column
           Chromatography-Free Protocol at Room Temperature

    • Authors: Yuliya E. Ryzhkova, Michail N. Elinson, Anatoly N. Vereshchagin, Kirill A. Karpenko, Fedor V. Ryzhkov, Ivan E. Ushakov, Mikhail P. Egorov
      First page: 615
      Abstract: Electrochemical synthesis suggested a mild, green and atom-efficient route to interesting and useful molecules, thus avoiding harsh chemical oxidizing and reducing agents used in traditional synthetic methods. Organic electrochemistry offers an excellent alternative to conventional methods of organic synthesis and creates a modern tool for carrying out organic synthesis, including cascade and multicomponent ones. In this research, a novel electrocatalytic multicomponent transformation was found: the electrochemical multicomponent assembly of arylaldehydes, N,N′-dimethylbarbituric acid and 4-hydroxy-6-methyl-2H-pyran-2-one in one pot reaction was carried out in alcohols in an undivided cell in the presence of alkali metal halides with the selective formation of substituted unsymmetrical 1′,3′,6-trimethyl-3-aryl-2′H,3H,4H-spiro[furo[3,2-c]pyran-2,5′-pyrimidine]-2′,4,4′,6′(1′H,3′H)-tetraones in 73–82% yields. This new electrocatalytic process is a selective, facile and efficient way to obtain spiro[furo[3,2-c]pyran-2,5′-pyrimidines]. According to screening molecular docking data using a self-made Python script in Flare, all synthesized compounds may be prominent for different medical applications, such as breast cancer, neurodegenerative diseases and treatments connected with urinary tract, bones and the cardiovascular system.
      Citation: Chemistry
      PubDate: 2022-06-19
      DOI: 10.3390/chemistry4020044
      Issue No: Vol. 4, No. 2 (2022)
       
  • Chemistry, Vol. 4, Pages 31-41: Photoelectron Circular Dichroism as a
           Probe of Chiral Hydrocarbons

    • Authors: Piero Decleva
      First page: 31
      Abstract: The sensitivity of Photoelectron Circular Dichroism (PECD) in the angular distribution of photoelectrons, a recent chiral technique, to detect chirality in pure hydrocarbons is investigated in a number of benchmark molecules. It is found that a very large chiral signal is expected, surpassing most current examples, giving a sure fingerprint of absolute configuration. On the other hand, the sensitivity to specific isomers or closely related molecules is relatively modest.
      Citation: Chemistry
      PubDate: 2022-01-13
      DOI: 10.3390/chemistry4010003
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 42-56: Valence-, Dipole- and Quadropole-Bound
           Electronically Excited States of Closed-Shell Anions Formed by
           Deprotonation of Cyano- and Ethynyl-Disubstituted Polycyclic Aromatic
           Hydrocarbons

    • Authors: Marie E. Strauss, Taylor J. Santaloci, Ryan C. Fortenberry
      First page: 42
      Abstract: Dicyano-functionalized benzene and naphthalene anion derivatives exhibit a relatively rich population of electronically excited states in stark contrast to many assumptions regarding the photophysics of anions in general. The present work has quantum chemically analyzed the potential electronically excited states of closed-shell anions created by replacing hydrogen atoms with valence-bound lone pairs in benzene and naphthalene difunctionalized with combinations of -CN and -C2H. Dicyanobenzene anion derivatives can exhibit dipole-bound excited states as long as the cyano groups are not in para position to one another. This also extends to cyanoethynylbenzene anions as well as deprotonated dicyano- and cyanoethynylnaphthalene anion derivatives. Diethynyl functionalization is less consistent. While large dipole moments are created in some cases for deprotonation on the -C2H group itself, the presence of electronically excited states beyond those that are dipole-bound is less consistent. Beyond these general trends, 2-dicyanonaphthalene-34 gives strong indication for exhibiting a quadrupole-bound excited state, and the 1-cyanoethynylnaphthalene-29 and -36 anion derivatives are shown to possess as many as two valence-bound excited states and one dipole-bound excited state. These photophysical properties may have an influence on regions where polycyclic aromatic hydrocarbons are known to exist such as in various astrochemical environments or even in combustion flames.
      Citation: Chemistry
      PubDate: 2022-01-24
      DOI: 10.3390/chemistry4010004
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 57-59: Acknowledgment to Reviewers of Chemistry
           in 2021

    • Authors: Chemistry Editorial Office Chemistry Editorial Office
      First page: 57
      Abstract: Rigorous peer-reviews are the basis of high-quality academic publishing [...]
      Citation: Chemistry
      PubDate: 2022-01-25
      DOI: 10.3390/chemistry4010005
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 60-76: Durable Polymer Coatings: A Comparative
           Study of PDMS-Based Nanocomposites as Protective Coatings for Stone
           Materials

    • Authors: Maduka L. Weththimuni, Marwa Ben Chobba, Donatella Sacchi, Mouna Messaoud, Maurizio Licchelli
      First page: 60
      Abstract: Nowadays, durable protective coatings receive more attention in the field of conservation for several reasons (they are cost effective, time consuming, more resistance, etc.). Hence, this study was focused on producing a multi-functional, durable coating to protect different stone materials, especially, Lecce stone, bricks, and marble. For this purpose, ZrO2-doped-ZnO-PDMS nanocomposites (PDMS, polydimethylsiloxane used as the binder) were synthesized by in situ reaction (doped nanoparticles were inserted into the polymer matrix during the synthesis of PDMS) and the performances of resulting coatings were examined by handling different experimental analyses. In particular, the study aimed to evaluate the durability properties of the coating along with the self-cleaning effect. As a result, the durability of the nanocomposite coating with respect to the well-known PDMS coating was assessed after exposure to two different ageing cycles: solar ageing (300 W, 1000 h) and humid chamber ageing (RH > 80%, T = 22 ± 3 °C, desiccator, 2 years). All the results were in good agreement with each other providing that newly prepared nanocomposite coating can be used as a durable protective coating for different stone materials.
      Citation: Chemistry
      PubDate: 2022-01-29
      DOI: 10.3390/chemistry4010006
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 77-97: Synthesis of Nitroarenes by Oxidation of
           Aryl Amines

    • Authors: Antonella Capperucci, Damiano Tanini
      First page: 77
      Abstract: Nitro compounds are an important class of organic molecules with broad application in organic synthesis, medicinal chemistry, and materials science. Among the variety of methodologies available for their synthesis, the direct oxidation of primary amines represents an attractive alternative route. Efforts towards the development of oxidative procedures for the synthesis of nitro derivatives have spanned over the past decades, leading to a wide variety of protocols for the selective oxidative conversion of amines to nitro derivatives. Methods for the synthesis of nitroarenes via oxidation of aryl amines, with particular emphasis on recent advances in the field, are summarised in this review.
      Citation: Chemistry
      PubDate: 2022-02-07
      DOI: 10.3390/chemistry4010007
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 98-111: Application of Elicitors at Two
           Maturation Stages of Vitis vinifera L. cv Monastrell: Changes in Skin Cell
           Walls

    • Authors: Diego F. Paladines-Quezada, Juan D. Moreno-Olivares, José I. Fernández-Fernández, Juan A. Bleda-Sánchez, Rocío Gil-Muñoz
      First page: 98
      Abstract: The aim of this study was to evaluate whether the application of two pre-harvest elicitors—methyl-jasmonate (MeJ) and benzothiadiazole (BTH)—to Monastrell grapes, at two maturation stages, affected the composition and structure of the skin cell walls (SCWs) to differing extents. This study was conducted in 2016–2017 on Vitis vinifera L. cv Monastrell. A water suspension of MeJ and BTH, and a mixture of both, was applied at veraison and mid-ripening. The composition of the berry SCW was analyzed. Environmental conditions caused substantial changes in SCW composition, especially at high temperatures. Indeed, a reduction of approximately 50% in the biosynthesis of hemicellulose, proteins and total phenols was observed, accompanied by a slight increase in cellulose and lignin. However, the application of the treatments also caused changes in some SCW constituents: increases in the concentration of phenols, proteins and lignin were observed, especially when the MeJ and MeJ + BTH treatments were applied at veraison. Likewise, a reduction in uronic acids was observed in the MeJ + BTH treatment applied at veraison. These changes in the SCWs could affect their structural characteristics, and therefore influence grape handling in the field and in the winery. Further studies are needed to determine the extent to which MeJ and BTH treatments affect other skin characteristics.
      Citation: Chemistry
      PubDate: 2022-02-12
      DOI: 10.3390/chemistry4010008
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 112-117: On-Surface Synthesis of Polypyridine:
           Strain Enforces Extended Linear Chains

    • Authors: Laerte L. Patera, Josef Amler, Jascha Repp
      First page: 112
      Abstract: Strain-induced on-surface transformations provide an appealing route to steer the selectivity towards desired products. Here, we demonstrate the selective on-surface synthesis of extended all-trans poly(2,6-pyridine) chains on Au(111). By combining high-resolution scanning tunneling and atomic force microscopy, we revealed the detailed chemical structure of the reaction products. Density functional theory calculations indicate that the synthesis of extended covalent structures is energetically favored over the formation of macrocycles, due to the minimization of internal strain. Our results consolidate the exploitation of internal strain relief as a driving force to promote selective on-surface reactions.
      Citation: Chemistry
      PubDate: 2022-02-16
      DOI: 10.3390/chemistry4010009
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 118-120: Current Density and Spectroscopy—A
           Themed Issue in Honor of Professor Riccardo Zanasi on the Occasion of His
           70th Birthday

    • Authors: Andrea Peluso, Guglielmo Monaco
      First page: 118
      Abstract: It is our great pleasure to introduce the Festschrift of Chemistry to honor Professor Riccardo Zanasi (Figure 1) on the occasion of his 70th birthday and to recognize his important contributions to quantum chemistry, particularly in the field of magnetic response and chiroptical spectroscopies [...]
      Citation: Chemistry
      PubDate: 2022-02-23
      DOI: 10.3390/chemistry4010010
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 121-136: Pectin Microspheres: Synthesis Methods,
           Properties, and Their Multidisciplinary Applications

    • Authors: Keila Gutierrez-Alvarado, Randall Chacón-Cerdas, Ricardo Starbird-Perez
      First page: 121
      Abstract: There is great contemporary interest in using cleaner technologies through green chemistry and utilizing biopolymers as raw material. Pectin is found on plant cell walls, and it is commonly extracted from fruit shells, mostly apples or citrus fruits. Pectin has applications in many areas of commercial relevance; for this reason, it is possible to find available information about novel methods to transform pectin and pursuing enhanced features, with the structuring of biopolymer microspheres being highly cited to enhance its activity. The structuring of polymers is a technique that has been growing in recent decades, due to its potential for diverse applications in various fields of science and technology. Several techniques are used for the synthesis of microspheres, such as ionotropic gelation, extrusion, aerosol drying, or emulsions, with the latter being the most commonly used method based on its reproducibility and simplicity. The most cited applications are in drug delivery, especially for the treatment of colon diseases and digestive-tract-related issues. In the industrial field, it is used for protecting encapsulated compounds; moreover, the environmental applications mainly include the bioremediation of toxic substances. However, there are still many possibilities for expanding the use of this biopolymer in the environmental field.
      Citation: Chemistry
      PubDate: 2022-03-01
      DOI: 10.3390/chemistry4010011
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 137-145:
           (18-Crown-6)-bis(tetrahydrofuran)-potassium Anthracenide: The Salt of a
           Free Radical Anion Crystallizing as a Kryptoracemate

    • Authors: Ivan Bernal, Roger A. Lalancette
      First page: 137
      Abstract: K[(18-crown-6)-bis(tetrahydrofuran)anthracenide] was independently prepared by three groups, and its structure described by two of them. The third structure description, though listed in the Cambridge Crystallographic Data Centre (CSD) collection, contains no space group or atomic coordinates, but the cell constants leave no doubt that it is the same species as the two others, which were reported in 2006 and 2016. The compound crystallizes in space group P21, with Z′ = 2.0 at T = 123 K and R = 4.91% (I), and at 100 K and R = 4.44% (II); both impressive results in their individual quality and agreement, despite differences in experimental methods and the temperature of data collection. A more detailed examination of the published data for (I) and (II) reveals that the correct description for this very unusual, and thus far unique substance, is that it contains a radical anion crystallizing as a kryptoracemate rather than as a simple example of a Sohncke space group with Z′ = 2.0. The anthracenide anions present in (I) and (II) are virtually identical; in contrast, the internal pair of cationic species differ from one another in the dissymmetry of the flexible tetrahydrofuran ligands, having significantly different internal and external torsional angles. The two THF molecules attached to the K(crown-ether) cations are not centrosymmetrically related, and this is what makes this portion of the asymmetric unit responsible for the crystal being a kryptoracemate. Our presentation will be based on the more fully documented sample (II), unless specifically stated.
      Citation: Chemistry
      PubDate: 2022-03-11
      DOI: 10.3390/chemistry4010012
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 146-155: Study on the Effects of Biologically
           Active Amino Acids on the Micellization of Anionic Surfactant Sodium
           Dodecyl Sulfate (SDS) at Different Temperatures

    • Authors: Fatima M. Elarbi, Zaineb O. Ettarhouni, Wanisa Abdussalam-Mohammed, Aysha B. Mezoughi
      First page: 146
      Abstract: The micellar properties of the anionic surfactant, sodium dodecyl sulfate (SDS) are modified by the biologically active amino acids. Amino acids (AAs) have experienced a variety of interactions and are proposed to influence SDS micelles due to their nominated hydrophobic interactions. The present study determines the critical micellar concentration (CMC) of SDS in aqueous solutions as well as in amino aqueous solutions. Three amino acids (glutamic acid, histidine, and tryptophan) are considered here. The conductometric measurements were carried out using a wide range of SDS concentrations at different temperatures. Surface tension experiments have also been applied to estimate many surface parameters including surface excess concentration (Γmax), surface occupied area per surfactant molecule (Amin), surface tension at CMC (γcmc), surface pressure at CMC (Πcmc) and Gibbs free energy of adsorption (∆Gads°), enthalpy ∆Hm° and the critical packing parameter (CPP). Interestingly, CMC values of SDS in water and in aqueous amino acids estimated by the surface tension method are comparable with the corresponding values obtained by the conductance method. The thermodynamic parameters of SDS micellization were also evaluated in both presence and absence of AAs. The additives of AAs work to reduce the CMC values, as well as the SDS thermodynamic parameters. This reduction is highly dependent on the hydrophobicity of the AA side chain. Negative values of ∆Gm°, ∆Hm° elucidate that micellization of SDS in the presence of amino acids is thermodynamically spontaneous and exothermic. The outcomes here might be utilized for pharmaceutical applications to stabilize proteins and inhibit protein aggregation.
      Citation: Chemistry
      PubDate: 2022-03-11
      DOI: 10.3390/chemistry4010013
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 156-167: Enantiopure Cyclometalated Rh(III) and
           Ir(III) Complexes Displaying Rigid Configuration at Metal Center: Design,
           Structures, Chiroptical Properties and Role of the Iodide Ligand

    • Authors: Antoine Groué, Jean-Philippe Tranchier, Geoffrey Gontard, Marion Jean, Nicolas Vanthuyne, Hani Amouri
      First page: 156
      Abstract: Enantiopure N-heterocyclic carbene half-sandwich metal complexes of the general formula [Cp*M(C^C:)I] (M = Rh, Ir; C^C: = NI-NHC; NI-H = Naphthalimide; NHC = N-heterocyclic carbene) are reported. The rhodium compound was obtained as a single isomer displaying six membered metallacycle and was resolved on chiral column chromatography to the corresponding enantiomers (S)-[Cp*Rh(C^C:)I] (S)-2 and (R)-[Cp*Rh(C^C:)I] (R)-2. The iridium congener, however, furnishes a pair of regioisomers, which were resolved into (S)-[Cp*Ir(C^C:)I] (S)-3 and (R)-[Cp*Ir(C^C:)I] (R)-3 and (S)-[Cp*Ir(C^C:)I] (S)-4 and (R)-[Cp*Ir(C^C:)I] (R)-4. These regioisomers differ from each other, only by the size of the metallacycle; five-membered for 3 and six-membered for 4. The molecular structures of (S)-2 and (S)-4 are reported. Moreover, the chiroptical properties of these compounds are presented and discussed. These compounds display exceptional stable configurations at the metal center in solution with enantiomerization barrier ΔG≠ up to 124 kJ/mol. This is because the nature of the naphthalimide-NHC clamp ligand and the iodide ligand contribute to their configuration’s robustness. In contrast to related complexes reported in the literature, which are often labile in solution.
      Citation: Chemistry
      PubDate: 2022-03-12
      DOI: 10.3390/chemistry4010014
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 168-184: The Structure and Location of 18-Crown-6
           Ether in Zeolites RHO and ZK-5

    • Authors: Antony Nearchou, Catherine Dejoie, Paul R. Raithby, Asel Sartbaeva
      First page: 168
      Abstract: The use of organic additives presents the greatest versatility and control of zeolite synthesis in order to prepare novel architectures for desired applications. Despite this prospect, there is little clarity of how organic additives are involved in framework assembly and the range of behaviours that are available. To address this issue, we have considered zeolites RHO and ZK-5 which can both be prepared using 18-crown-6 ether as an additive. Previously, this additive has shown to employ different structure directing behaviours to assemble a variety of zeolites. We have used high resolution powder X-ray diffraction and Rietveld refinement to determine structural models for zeolites RHO and ZK-5 with 18-crown-6 ether occluded in the framework. In doing so, we can observe the identity, location and orientation of the occluded additive and reason the structure directing behaviour in synthesis. We report that the isolated 18-crown-6 ether molecule is involved in the assembly of zeolite RHO, and for zeolite ZK-5 it is the K+ coordinated macrocation. In both cases the relevant additive is disordered in the framework, suggesting that they behave as space-filling species that stabilise the formation of the α-cage.
      Citation: Chemistry
      PubDate: 2022-03-13
      DOI: 10.3390/chemistry4010015
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 185-195: Solvation Effects on the Thermal Helix
           Inversion of Molecular Motors from QM/MM Calculations

    • Authors: Jin Wen, Meifang Zhu, Leticia González
      First page: 185
      Abstract: Molecular motors convert light and thermal energies into mechanical work, offering good opportunities to design novel molecular devices. Among them, molecular motors alternate a photoisomerization and a thermal helix inversion to achieve unidirectional rotation. The rotational speed is limited by the helix inversion step, which in turn is governed by a barrier in the electronic ground state. In this work, we systematically study the solvation effect on the thermal process of selected molecular motors, comparing reaction barriers obtained from both density functional theory (DFT) in the isolated system and umbrella sampling within a hybrid quantum mechanics/molecular mechanics (QM/MM) model in solution. We find more prominent solvation effects on those molecular motors with larger dipole moments. The results could provide insight into how to functionalize molecular motors to speed up their rotation.
      Citation: Chemistry
      PubDate: 2022-03-15
      DOI: 10.3390/chemistry4010016
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 196-205: Long-Range Supramolecular Synthon
           Isomerism: Insight from a Case Study of Vinylic Tellurium Trihalides
           Cl(Ph)C=C(Ph)TeX3 (X = Cl, I)

    • Authors: Yury V. Torubaev, Aida S. Samigullina
      First page: 196
      Abstract: A slight modification of the synthetic procedure resulted in a new (Cc) polymorph of vinylic tellurium-trichloride Z-Cl(Ph)C=C(Ph)TeCl3 (1, β-form) which is stabilized by Te⋯Cl chalcogen bonds, assembling its molecules into the zigzag chains. Such a packing motive is in contrast to the known (Pca21) polymorph of Z-Cl(Ph)C=C(Ph)TeCl3 (1, α-form, CCDC refcode: BESHOW), which is built upon Te⋯π(Ph) chalcogen bonded chains. We noted a similar case of [Te⋯halogen] vs. [Te⋯π(Ph)] supramolecular synthon polymorphism in its triiodide congener Z-Cl(Ph)C=CPh(TeI3) (2, α and β-polymorphic forms). Quantum chemical calculations of the intermolecular interaction and lattice energies for 1α–β and 2α–β supported the assumption that α is thermodynamic while β is a kinetic form. Kinetic forms 1β and 2β are isostructural (Cc), while the thermodynamic forms 1α (Pca21) and 2α (P21/c) are not and feature an unusual example of long-range supramolecular synthon module isomerism. In other words, 1α–2α pairs demonstrate very similarly to isostructural Te⋯πPh ChB stabilized chains, which are further packed differently relative to each other, following different angular geometry of type-I Cl⋯Cl and type-II I⋯I halogen bonding. These structural considerations are backed by quantum chemical calculations that support the proposed hierarchy of primary and secondary supramolecular synthons and the assignment of α and β as thermodynamic and kinetic forms, respectively.
      Citation: Chemistry
      PubDate: 2022-03-17
      DOI: 10.3390/chemistry4010017
      Issue No: Vol. 4, No. 1 (2022)
       
  • Chemistry, Vol. 4, Pages 206-215: A Sustainable Synthetic Approach to the
           Indaceno[1,2-b:5,6-b′]dithiophene (IDT) Core through Cascade
           Cyclization–Deprotection Reactions

    • Authors: Giacomo Forti, Andrea Nitti, Gabriele Bianchi, Riccardo Po, Dario Pasini
      First page: 206
      Abstract: Bulk heterojunction organic solar cells (BHJs) are competitive within the emerging photovoltaic technologies for solar energy conversion because of their unique advantages. Their development has been boosted recently by the introduction of nonfullerene electron acceptors (NFAs), to be used in combination with a polymeric electron donor in the active layer composition. Many of the recent advances in NFAs are attributable to the class of fused-ring electron acceptors (FREAs), which is now predominant, with one of the most notable examples being formed with a fused five-member-ring indaceno[1,2-b:5,6-b′]dithiophene (IDT) core. Here, we propose a novel and more sustainable synthesis for the IDT core. Our approach bypasses tin derivatives needed in the Stille condensation, whose byproducts are toxic and difficult to dispose of, and it makes use of cascade reactions, effectively reducing the number of synthetic steps.
      Citation: Chemistry
      PubDate: 2022-03-21
      DOI: 10.3390/chemistry4010018
      Issue No: Vol. 4, No. 1 (2022)
       
 
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