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  Subjects -> CHEMISTRY (Total: 881 journals)
    - ANALYTICAL CHEMISTRY (54 journals)
    - CHEMISTRY (616 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (43 journals)
    - ORGANIC CHEMISTRY (48 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (616 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 14)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Hybrid Journal   (Followers: 43)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 21)
ACS Combinatorial Science     Hybrid Journal   (Followers: 23)
ACS Macro Letters     Hybrid Journal   (Followers: 25)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 41)
ACS Nano     Hybrid Journal   (Followers: 280)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription  
ACS Synthetic Biology     Hybrid Journal   (Followers: 24)
Acta Chemica Iasi     Open Access   (Followers: 5)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 7)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 6)
Advanced Functional Materials     Hybrid Journal   (Followers: 57)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 67)
Advances in Chemical Science     Open Access   (Followers: 18)
Advances in Chemistry     Open Access   (Followers: 21)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19)
Advances in Drug Research     Full-text available via subscription   (Followers: 24)
Advances in Environmental Chemistry     Open Access   (Followers: 5)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 25)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 16)
Advances in Polymer Science     Hybrid Journal   (Followers: 44)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 3)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 65)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 20)
American Journal of Chemistry     Open Access   (Followers: 30)
American Journal of Plant Physiology     Open Access   (Followers: 11)
American Mineralogist     Hybrid Journal   (Followers: 15)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 169)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 247)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 5)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
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)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 32)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 2)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Hybrid Journal   (Followers: 359)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 10)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 21)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 132)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 87)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     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: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 70)
Catalysis for Sustainable Energy     Open Access   (Followers: 8)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 10)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 20)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 74)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 26)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 191)
Chemical Science     Open Access   (Followers: 25)
Chemical Technology     Open Access   (Followers: 26)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
Chemistry & Industry     Hybrid Journal   (Followers: 7)
Chemistry - A European Journal     Hybrid Journal   (Followers: 159)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 21)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Open Access   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 43)
Chemistry of Materials     Hybrid Journal   (Followers: 259)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 19)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 11)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 6)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Cogent Chemistry     Open Access   (Followers: 1)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Communications Chemistry     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 7)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 4)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 6)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 6)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal  
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 14)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 69)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 3)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  

        1 2 3 4 | Last

Journal Cover
Canadian Journal of Chemistry
Journal Prestige (SJR): 0.29
Citation Impact (citeScore): 1
Number of Followers: 10  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0008-4042 - ISSN (Online) 1480-3291
Published by NRC Research Press Homepage  [21 journals]
  • Effects of Li doping on microstructural and electrical properties of
           ZnO–MgO–Al2O3 linear resistance ceramics
    • Abstract: Canadian Journal of Chemistry, Volume 96, Issue 8, Page x-x, August 2018.

      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-22T07:00:00Z
      DOI: 10.1139/cjc-2017-0471
       
  • Tribute to J. Peter Guthrie, FCIC, FRSC 1942–2017
    • Authors: Mark S. Workentin, Robert H.E. Hudson
      Abstract: Canadian Journal of Chemistry, e-First Articles.

      Citation: Canadian Journal of Chemistry
      PubDate: 2018-07-17T12:18:05Z
      DOI: 10.1139/cjc-2018-0144
       
  • Two novel colorimetric probes (5-HMBA-FH and 3-HMBA-FH) based on
           fluorescein for copper(II) ion detection
    • Authors: Guanhong Liu, Peipei Ren, Fan Yang, Xuekai Dou, Jun Wang, Youtao Song
      Pages: 1 - 9
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Two novel isomeric colorimetric probes are established for simultaneous determination of copper ions using 2-hydroxy-5-methoxybenzaldehyde fluorescein hydrazone (5-HMBA-FH) and 2-hydroxy-3-methoxybenzaldehyde fluorescein hydrazone (3-HMBA-FH). They are synthesized by reacting fluorescein hydrazide with 2-hydroxy-5-methoxybenzaldehyde and 2-hydroxy-3-methoxybenzaldehyde, respectively, and then characterized by 1H-NMR, 13C-NMR, and infrared spectrum. The addition of copper ions to the solutions of two novel colorimetric probes can generate the obviously peaks at 498 nm in UV–vis absorption spectra along with a rapid colour change from colourless to dark yellow. The detection limits of the method for Cu2+ ion were 3.442 × 10−6 mol/L and 3.682 × 10−6 mol/L separately for 5-HMBA-FH and 3-HMBA-FH, respectively. The additions of other metal ions hardly affect the determination of copper ions. The proposed method was successfully applied to the analysis of Cu2+ ions in various samples. This method possesses high sensitivity, high simplicity, and minimized interference and will provide a great advantage in detecting copper ions in the environment, food, and medical applications.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-07-13T07:00:00Z
      DOI: 10.1139/cjc-2018-0105
       
  • A novel copper selective sensor based on ion imprinted 2-vinylpyridine
           polymer
    • Authors: Murat Yolcu, Nurşen Dere
      Pages: 1 - 10
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      A novel potentiometric Cu2+-selective microsensor has been developed that is based upon ion imprinted 2-vinylpyridine polymer. The polymer was synthesized using Cu(II) ions, 2-vinylpyridine, methacrylic acid, and ethylene glycol dimethacrylate as a template, functional monomer, and cross-linker, respectively. The resultant polymer was used as ionophore to obtain a selective potentiometric response towards Cu(II) ions in the structure of the PVC membrane. The detection limit of the microsensor was determined to be 8.4 × 10−7 mol/L, and its response time was considerably short (less than 15 s). The prepared microsensor exhibited a near-Nernstian response for Cu(II) ions over the concentration range of 10−1 to 10−6 mol/L, with a slope of 28.5 mV per decade over 2 months, and without any considerable divergence in potentials. The microsensor was effectively performed in a pH range between 4.0 and 7.0 and used as an indicator electrode in the potentiometric titration of Cu(II) ions with EDTA. The proposed microsensor has been successfully demonstrated for the determination of copper in a number of environmental water samples. The obtained potentiometric results were in good harmony with the results obtained by the AAS method.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-07-11T07:00:00Z
      DOI: 10.1139/cjc-2018-0178
       
  • Nebivolol nanoparticles: a first catalytic use in Biginelli and
           Biginelli-like reactions
    • Authors: Anamika Khaskel, Pranjit Barman, Subir Kumar Maiti, Utpal Jana
      Pages: 1 - 5
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Herein, we report the catalytic activity of nebivolol nanoparticles a novel organocatalyst for the synthesis of DHPMs and DHPM-5-carboxamides. The nanoparticles are confirmed by DSC, TEM, AFM, and IR spectroscopy. The catalyst can be readily recovered and reused for the next four runs without any significant impact on the yields of the products. The products are fully characterized by FTIR, 1H NMR, 13C NMR, and distortionless enhanced polarization transfer (DEPT) NMR. The methodology adopted here offers several advantages such as solvent-free reaction, low loading of catalyst, short reaction times, and quantifiable yields.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-07-05T07:00:00Z
      DOI: 10.1139/cjc-2017-0621
       
  • Unexpected medium effect on the mechanism for aminolysis of aryl phenyl
           carbonates in acetonitrile and H2O: transition-state structure in the
           catalytic pathway
    • Authors: Ik-Hwan Um, Ji-Hyun Song, Ae-Ri Bae, Julian M. Dust
      Pages: 1 - 10
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Upward curvature in the kinetic plots of pseudo first-order rate constants (kobsd) vs. [amine] for the aminolysis of aryl phenyl carbonates (5a–5j) in MeCN demonstrates that these reactions proceed via a zwitterionic tetrahedral intermediate (T±) that partitions between catalyzed and uncatalyzed routes to give the products. Yukawa–Tsuno plots for the reactions of 5a–5j with piperidine result in excellent linear correlations with ρY = 4.82 and r = 0.47 for the uncatalyzed reaction versus ρY = 2.21 and r = 0.21 for the catalyzed reaction. Brønsted plots for reactions of 4-(ethoxycarbonyl)-phenyl phenyl carbonate (5f) with a series of cyclic secondary amines exhibit excellent linear correlations with βnuc = 0.87 and 0.58 for the uncatalyzed and catalyzed reactions, respectively. The ΔH‡ and ΔS‡ values are 0.92 kcal/mol and –50.1 cal/mol K, respectively, for the catalyzed reaction of 5f with piperidine. Deuterium kinetic isotope effects found for reactions of 5f with piperidine/deuterated piperidine are 0.84 (uncatalyzed) and 1.42 (catalyzed). Multi-parameter analysis supports a concerted catalytic pathway involving a six-membered cyclic transition state rather than a traditionally accepted stepwise pathway with an anionic intermediate. The current unexpected results, where T± is the essential central intermediate in this aminolysis, contrast with previous calculation studies that deemed T± unstable in gas phase or MeCN.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-07-05T07:00:00Z
      DOI: 10.1139/cjc-2018-0204
       
  • Retraction: Effects of Li-doping on microstructural and electrical
           properties of ZnO–MgO–Al2O3 linear resistance ceramics
    • Authors: Rong Yang, Xiao Qu, Mao-Hua Wang
      Pages: 1 - 1
      Abstract: Canadian Journal of Chemistry, e-First Articles.

      Citation: Canadian Journal of Chemistry
      PubDate: 2018-07-03T12:34:44Z
      DOI: 10.1139/cjc-2018-0257
       
  • Synthesis and self-assembly of thiol-modified tellurophenes
    • Authors: Gabrielle C. Hoover, Jennifer Ham, Connie Tang, Elisa I. Carrera, Dwight S. Seferos
      Pages: 1 - 5
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      An asymmetric thiol-modified tellurophene was designed and synthesized, and the ability of the compound to form a monolayer on a gold electrode was confirmed. The surface-active tellurophene was synthesized using Cadiot–Chodkiewicz coupling followed by ring closing and thiol modification. The tellurophene compound forms a monolayer on gold surfaces from a concentrated solution within 24 h. The ability of the compound to conjugate to gold is confirmed by X-ray photoelectron spectroscopy (XPS). A surface blocking experiment was used to evaluate the extent of formation of a monolayer on a gold electrode.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-06-29T10:46:00Z
      DOI: 10.1139/cjc-2018-0077
       
  • Theoretical study on the acidities of pyrrole, indole, carbazole and their
           hydrocarbon analogues in DMSO
    • Authors: Berkane Ariche, Ali Rahmouni
      Pages: 1 - 9
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      SMD and IEF-PCM continuum solvation models have been used, in combination with three quantum chemistry methods (B3LYP, M062X, and CBS-QB3), to study the acidities of pyrrole, indole, and carbazole, as well as their hydrocarbon analogues in DMSO, following a direct thermodynamic method. Theoretical parameters such as aromaticity indices (HOMA and SA), molecular electrostatic potential (MEP), and atomic charges have been calculated using B3LYP/6-311++G(d,p) level of theory. Calculated pKa values indicate that there is generally good agreement with experimental data, with all deviations being less than the acceptable error for directly calculated pKa values. The M062X functional combined with the SMD solvation model provided the most accurate pKa values. The MEP surfaces clearly show the electron density change accompanying the deprotonation process and explain the relative stability of conjugate bases. The HOMA aromaticity indices seem to be directly related to acidity strength. The collected data have been used to elucidate the pKa trends for the series of molecules under consideration.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-06-23T07:00:00Z
      DOI: 10.1139/cjc-2018-0032
       
  • Density functional study of guanidine-azole salts as energetic materials
    • Authors: Si-Yu Xu, Zhou-Yu Meng, Feng-Qi Zhao, Xue-Hai Ju
      Pages: 1 - 8
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      A series of guanidine cations and azole anions were designed for use as energetic salts. Their geometrical structures were optimized by the density functional theory (DFT) method. The counter ions were matched by the similar magnitude of the electron affinity (EA) of the cation and the ionization potential (IP) of the anion. The densities, heats of formation, detonation parameters, and impact sensitivity were predicted. The incorporation of guanidine cations and diazole anions are favorable to form thermal stable salts except cation A1. The diaminoguanidine cation has greater impact on the density and detonation properties of the salts than the triaminoguanidine cation. 2-Amino-3-nitroamino-4,5-nitro-dinitropyrazole is the best anion for advancing the detonation performance among all the anions. Incorporating the C=O bond into the guanidine cations enhances the density and detonation performance of the guanidine-azole salts. The salts containing III1–III4 anion have better detonation properties than HMX, indicating that these salts are potential energetic compounds. Compared with RDX or HMX, some salts with diaminoguanidine cation display lower impact sensitivity.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-06-14T07:00:00Z
      DOI: 10.1139/cjc-2018-0106
       
  • Adsorption mechanism of CO molecule on Al(111) surface: periodic DFT
           investigation
    • Authors: Chenhong Xu, Suqin Zhou, Jing Chen, Yuxiang Wang, Lei He
      Pages: 1 - 7
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      The adsorption mechanism of the CO molecule on Al(111) surface has been investigated systematically at the atom-molecule level by the method of periodic density functional theory. The adsorption energies, adsorption structures, charge transfer, and density of states have been calculated in a wide range of coverage. It is found that the hcp-hollow site is the energetically favorable site. A significant positive correlation has been found between the adsorption energy (Eads) and coverage. The adsorbed CO molecules are almost perpendicular on the surface with the C atom facing the surface. There is an obvious charge transfer from Al atoms to the C atom; the Al atoms that have interaction with the C atom offer the most charge. The 4σ, 1π, and 5σ molecular orbitals of CO are found to contribute to bonding with the Al. The charges filling in the 2π molecular orbital contribute to C–O bond activation. In conclusion, the passivation of aluminum surface and the activation of CO molecule occur simultaneously in the adsorption of CO on Al surface.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-06-14T07:00:00Z
      DOI: 10.1139/cjc-2018-0169
       
  • Novel N-chloramine precursors for antimicrobial application: synthesis and
           facile covalent immobilization on polyurethane surface based on
           perfluorophenyl azide (PFPA) chemistry
    • Authors: Lingdong Li, Fengxiang Zhang, Fangyuan Gai, Hao Zhou, Xiaofang Chi, Hande Wang, Zongbao Zhao (Kent)
      Pages: 1 - 10
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      To control the pathogen cross contaminations on medical material surface, there is a pressing need to develop antimicrobial materials with highly efficacious surface biocidal activity. In this work, N-chloramine precursors containing a quaternary ammonium unit and perfluorophenyl azide unit were synthesized and covalently immobilized on inert polyurethane (PU) film upon UV light irradiation. The surface modification was confirmed by contact angle, Fourier transform infrared (ATR FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) analyses. After bleaching treatment, satisfactory biocidal activity was achieved for the surface-modified PU films. It was found that the introduced surface QA center contributed an even faster surface contact killing behavior and that precursors with a longer structural linker caused higher surface chlorine content and higher antimicrobial efficacy. This approach provides a novel and facile method that enables the covalent immobilization of N-chloramine precursors on inert polymeric surface to produce durable antimicrobial materials.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-06-12T07:00:00Z
      DOI: 10.1139/cjc-2018-0156
       
  • Computational study of polarizability anisotropies
    • Authors: Delano P. Chong
      Pages: 1 - 5
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      The dipole polarizabilities (α) and polarizability anisotropies (Δα) of over 20 molecules are calculated to search for negative Δα. The geometry of each molecule is first optimized at the level of CCSD(T)/cc-pVQZ. Then, the α tensors are computed both with CCSD(T)/daug-cc-pVTZ in Gaussian 09 and with the exchange-correlation potential Vxc known as SAOP in the Amsterdam density functional theory program called ADF and a large basis set called QZ3P-3DIFFUSE. In addition to the popular formula of the ΔαRaman connected with Raman spectroscopy, we also present values of an alternative definition of the polarizability anisotropy ΔαKerr connected with Kerr spectroscopy, recently proposed by Kampfrath and colleagues (2018. Chem. Phys. Lett. 692: 319). On one hand, the signs of many ΔαRaman are undetermined; on the other hand, we obtain negative ΔαKerr for more than one-half of the small molecules studied. Of the 24 molecules studied, 18 have negative ΔαKerr.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-06-08T07:00:00Z
      DOI: 10.1139/cjc-2018-0171
       
  • Systematic evaluation of inorganic salts as a heat sink for the
           magnesiothermic reduction of silica
    • Authors: Logesh Khanna, Yiqi Lai, Mita Dasog
      Pages: 1 - 4
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      In this study, the effectivity of a series of inorganic salts, sodium chloride, calcium chloride, magnesium chloride, potassium chloride, and sodium bromide as heat sinks during magnesiothermic reduction of silica to porous silicon was investigated. The salts were chosen based on cost, thermal stability, ability to remain chemically inert during the reduction process, and ease of removal after the reaction. The structural integrity of the spherical porous silicon nanoparticles was observed using scanning electron microscopy, the surface area was determined via nitrogen adsorption experiments, and the crystallite size was determined using powder X-ray diffraction analysis; together, these were used to determine the efficacy of each salt. The ability of a salt to act as an effective heat sink was found to be highly correlated and principally dependent on the heat capacity of the salt. Calcium chloride was found to be the most effective heat sink overall among the five heat sinks investigated here.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-06-08T07:00:00Z
      DOI: 10.1139/cjc-2018-0165
       
  • Medium effect on the α-effect for nucleophilic substitution reactions of
           p-nitrophenyl acetate with benzohydroxamates and m-chlorophenoxide in
           DMSO–H2O mixtures as contrasts with MeCN–H2O mixtures: comparing two
           very different polar aprotic solvent components
    • Authors: Ik-Hwan Um, Hyun-Jung Moon, Young-Hee Shin, Julian M. Dust
      Pages: 1 - 7
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      A kinetic study is reported on nucleophilic substitution reactions of p-nitrophenyl acetate (1a) with three α-effect nucleophiles, benzohydroxamate (BHA–), p-methylbenzohydroxamate (MBHA–), and p-methyl-N-methylbenzohydroxamate (M2BHA–), and a reference nucleophile, m-chlorophenoxide (m-ClPhO–), in DMSO–H2O mixtures of varying compositions at 25.0 ± 0.1 °C. Second-order rate constants for the reactions with BHA– and MBHA– decrease upon addition of DMSO to the reaction medium up to 60 mol % DMSO and then increase thereafter only a little. In contrast, M2BHA– and m-ClPhO– become much more reactive as the DMSO content in the medium increases. Such contrasting medium effects on reactivity are consistent with the report that hydroxamic acids behave as OH acids in H2O but as NH acids in dipolar aprotic solvents (e.g., DMSO and MeCN). It has been concluded that BHA– and MBHA– form an equilibrium of a reactive form I with less reactive species II in DMSO–H2O mixtures and the position of the equilibrium is dependent on solvent compositions. BHA– and MBHA– exhibit the α-effect in H2O but not in in 90 mol % DMSO. In contrast, the α-effect yielded by M2BHA– increases steeply up to 70 mol % DMSO and then levels off thereafter.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-29T07:00:00Z
      DOI: 10.1139/cjc-2018-0103
       
  • A prelude to building mathematical models for polypeptide folding:
           analysis on the conformational potential energy hypersurface
           cross-sections of N-acetyl-glycyl-glycine-N′-methylamide
    • Authors: John Justine S. Villar, Logine Negm, Anita Rágyanszki, David H. Setiadi, Adrian Roy L. Valdez, Béla Viskolcz, Imre G. Csizmadia
      Pages: 1 - 10
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Finding a relationship on how a three-dimensional protein folds from its linear amino acid chain gets more complex with increasing chain length, so working on a smaller peptide conformational problem can provide initial ideas on what are the main molecular forces and how these influence the folding process. Following the study of conformations of amino acid units entering the proteins to understand the secondary structure of small peptides, this paper proposes mathematical models for the several two-rotor cross-sections of the five-dimensional N-acetyl-glycyl-glycine-N′-methylamide potential energy hypersurface (PEHS). These cross-sections are extracted along the first glycine subunit, with its coordinates fixed at the five energy minima of the glycine diamide. The resulting mathematical models yield an average RMSE of 1.36 kJ mol−1 and an average R2 of 0.9923 with respect to energy values obtained from DFT calculations. The minima geometries obtained from these models are also in good agreement with DFT-optimized energy minima conformers. An important aspect of this study also tackles the relationship between the PEHS of the glycyl-glycine diamide and its glycine subunits. It has been observed that there are deviations up to 28.35 kJ mol−1 and 29.52 kJ mol−1 between the PEHS cross-sections along γL and γD conformations, respectively, in the first glycine subunit. This may suggest that there are significant backbone–backbone intermolecular forces acting on the dipeptide. The abovementioned findings can help in developing more complex mathematical models for polypeptide folding from amino acid subunits.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-28T07:00:00Z
      DOI: 10.1139/cjc-2018-0017
       
  • Synthesis, reactivity, and antimicrobial properties of boron-containing
           4-ethyl-3-thiosemicarbazide derivatives
    • Authors: Ryan S. Scott, Alex J. Veinot, Darcie L. Stack, Patrick T. Gormley, B. Ninh Khuong, Christopher M. Vogels, Jason D. Masuda, Felix J. Baerlocher, Tyson J. MacCormack, Stephen A. Westcott
      Pages: 1 - 6
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      The addition of 4-ethyl-3-thiosemicarbazide to benzaldehyde and boronic acid containing derivatives afforded the corresponding thiosemicarbazones (1–3) or benzodiazaborines (4–6) depending on the position of the boronic acid within the ring. All compounds have been characterized fully including an X-ray diffraction study of the methoxy-containing benzodiazaborine 6. Attempts to coordinate thiosemicarbazones 2 and 3 to palladium(II) acetate were unsuccessful; however, addition of the non-boron-containing derivative 1 to palladium afforded complex 7 whose molecular structure was determined by an X-ray diffraction study. The initial bioactivities of compounds 1–7 were examined against two fungi, Aspergillus niger and Saccharomyces cerevisiae, and two bacteria, Bacillus cereus and Pseudomonas aeruginosa.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-24T07:00:00Z
      DOI: 10.1139/cjc-2018-0108
       
  • Facile approach for synthesis of stable, efficient, and recyclable ZnO
           through pulsed sonication and its application for degradation of
           recalcitrant azo dyes in wastewater
    • Authors: G. Kumaravel Dinesh, Rameshkumar Saranya
      Pages: 1 - 9
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      In the present study, the ultrasound in pulsed mode was used as a part of an advanced oxidation method. The influence of the pulsed ultrasound mode for the preparation of the zinc oxide (ZnO) wurtzite nanoparticle was investigated. The catalysts synthesized were analysed using SEM, TEM, EDAX, BET surface area, XRD, and DRS to study their morphological and structural characterizations. The ZnO nanoparticles exhibited a highly hexagonal structure from pulsed sonication synthesis route. The efficiency of the decolourization of the reactive red 4 (RR4) dye was studied under different operation parameters such as dye concentration, initial solution pH, oxidant (e.g., H2O2) concentration, and catalyst loading. The hybrid combined process of pulsed sonolysis, pH (4.0), H2O2 (17.64 mmol), and catalyst (0.35 g/L) achieved 97% degradation and 87.5% chemical oxygen demand removal in about 20 min of reaction time. The cyclic degradation studies of RR4 removal with 0.35 g/L of ZnO showed the reusability of catalyst up to the fifth removal cycle with negligible loss in the catalytic performance. GC–MS study, used for the detection of the RR4 intermediates, revealed the oxidation–reduction reaction by the reactive radicals proceeded via the reductive cleavage of the azo bonds. The studied process, based on the pulsed ultrasound, is found to be effective for the degradation of RR4 dye.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-23T07:00:00Z
      DOI: 10.1139/cjc-2017-0696
       
  • Synthesis and fluorescence spectral studies of novel
           quinolylbenzothiazole-based sensors for selective detection of Fe3+ ion
    • Authors: Peng Wang, Xiaoyan Liu, Jiaxin Fu, Yongxin Chang, Li Yang, Kuoxi Xu
      Pages: 1 - 7
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Four novel fluorescence sensors bearing a quinolylbenzothiazole platform were synthesized and characterized. The sensors displayed excellent selectivity and highly sensitive fluorescence response to Fe3+ ion in H2O/DMSO buffer solution (1:4 volume ratio; Tris-HCl, 0.01 mol/L; pH = 7.40) at 500 nm originating from quinolylbenzothiazole fluorophore group. Other cations, namely Li+, Na+, K+, Mg2+, Ca2+, Co2+, Ni2+, Cd2+, Cu2+, Zn2+, Mn2+, Ba2+, Pb2+, Hg2+, Al3+, and Eu3+, showed no appreciable change in fluorescence spectrum. The binding stoichiometry between sensors L1, L2, L3, or L4 and Fe3+ was observed to be 1:1 based on fluorescence titration and Jobs plot analysis. The detection limits of L1, L2, L3, and L4 for Fe3+ were found to be 0.155, 0.362, 0.249, and 0.517 μmol/L, respectively. Furthermore, possible utilization of sensors to detect Fe3+ in living HeLa cells was also investigated by confocal fluorescence microscopy.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-23T07:00:00Z
      DOI: 10.1139/cjc-2017-0741
       
  • Visible-light degradation of Orange II using an Fe(II)–terpyridine
           complex grafted onto TiO2 surface
    • Authors: Benjamin Stewart, Peipei Huang, He He, Thomas Fenton, Gonghu Li
      Pages: 1 - 6
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      The photo-Fenton process employs light, iron species, and H2O2 to oxidize organic pollutants. In this study, a coordination complex, Fe(II)–terpyridine, was covalently grafted onto TiO2 surfaces via a light-harvesting linkage for use in the photo-Fenton reaction. The surface Fe(II)–terpyridine complex was characterized with techniques, including microscopy and spectroscopy, and was investigated in the degradation of Orange II in the presence of H2O2. Under visible-light irradiation, slightly higher activity was obtained using the surface Fe(II)–terpyridine catalyst than using photoactivated TiO2 nanoparticles under UV light. Furthermore, the Fe(II)–terpyridine complex grafted on TiO2 showed significantly greater activity than the same complex grafted on ZrO2 in the degradation of Orange II. A possible explanation for this observation was discussed that involves the formation of high valent oxoiron species on TiO2 in the photo-Fenton process.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-22T07:00:00Z
      DOI: 10.1139/cjc-2017-0509
       
  • Physicochemical, catalytic, and antimicrobial activities of porous cobalt
           oxide nanoparticles (kinetics study of H2O2 decomposition using
           fluorometric and gasometric methods)
    • Authors: Marwa M. Ibrahim, Sahar A. El-Molla
      Pages: 1 - 7
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Co3O4 nanomaterials were prepared by different methods. The samples were nominated as Co3O4 (Pr), Co3O4 (Co), and Co3O4 (Hy) due to preparation by precipitation, combustion, and a hydrothermal method, respectively. These nanomaterials were characterized by studying their structural, morphological, and surface properties. The catalytic activity was evaluated by following H2O2 decomposition through fluorometric and gasometric methods. The obtained results showed that the catalytic efficiency of the catalysts was affected by their preparation methods. The order of catalytic activities of the investigated samples using fluorometric method is compatible with that obtained by gasometric method. Co3O4 (Hy) exhibited much higher catalytic activity due to the high surface area, small particle size, different oxidation states, different shapes, and the high production of hydroxyl radical. The antimicrobial activity is studied against standard bacterial and fungal strains, and the studies showed that the hydrothermal method enhanced antimicrobial activity more than other preparation methods.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-14T07:00:00Z
      DOI: 10.1139/cjc-2017-0680
       
  • Synthesis of a simply modified electrochemical nicotine sensor based on
           silver nanoparticles
    • Authors: M.A. Ameer, A.M. Fekry, S.M. Azab, M. Shehata
      Pages: 1 - 7
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      An innovative electrochemical nicotine modified sensor was created by chemically mixing a carbon paste with silver nano powder to prepare an Ag nanoparticle modified carbon paste electrode. Different electrochemical techniques including cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy in both aqueous and micellar media were used. The surface morphology was also detected using scanning electron microscope and energy dispersive X-ray analysis techniques. Nicotine measurements were investigated in Britton–Robinson buffer solutions with a pH range of 2.0–8.0 containing 1.0 mmol/L sodium dodecyl sulfate. The electrode-based NIC sensor exhibited a high sensitivity in quantitative analysis, and its detection limit could be as low as 0.0036 μmol/L with linearity ranging from 0.8 μmol/L to 800 μmol/L. In addition, due to its good reproducibility, anti-interference performance, and long-term stability, the proposed sensor is capable of detecting trace levels of nicotine in urine samples and different brands of commercial cigarettes.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-08T07:00:00Z
      DOI: 10.1139/cjc-2017-0492
       
  • Conversion of Symphytum officinale and Panicum virgatum plant extracts to
           5-hydroxymethylfurfural catalysed by metal chlorides in ionic liquids
    • Authors: Alexandrine L. Martel, Sabine Montaut, Gerardo Ulíbarri, Graeme A. Spiers
      Pages: 1 - 6
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      The present work examined the potential for two plants grown on Canadian soil, Symphytum officinale L. (common comfrey) and Panicum virgatum L. (switchgrass), to produce 5-hydroxymethylfurfural using metal chloride catalysis in two ionic liquids, 1-butyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium chloride. Furthermore, two pre-treatments, namely the dilute sulfuric acid treatment and the methanol extraction, were studied as a way to improve sugar availability and increase 5-hydroxymethylfurfural yields compared with untreated biomass. The 0.5 mol/L H2SO4 hydrolysis under autoclave conditions produced sugar-rich extracts containing 230 ± 23 mg of sugars per gram of hydrolysed biomass for comfrey and 425 ± 13 mg of sugars per gram of hydrolysed biomass for switchgrass. The methanol extraction produced extracts high in simple sugars with concentration of 300 ± 60 mg of sugars per gram of dry extract for comfrey and 202 ± 16 mg of sugars per gram of dry extract for switchgrass. The yield of 5-hydroxymethylfurfural was improved from less than 1% using untreated biomass to 6.04% and 18.0% using dry methanol extracts of comfrey and switchgrass, respectively. These yields, although small, are important, as they show for the first time that a methanol extract could enhance the metal chloride catalysis in ionic liquids for 5-hydroxymethylfurfural production from biomass.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-05-07T07:00:00Z
      DOI: 10.1139/cjc-2017-0663
       
  • Fe(NO3)3·9H2O-catalyzed aerobic oxidative deoximation of ketoximes and
           aldoximes under mild conditions
    • Authors: Yongshu Li, Nizhou Xu, Guangyao Mei, Yun Zhao, Yiyong Zhao, Jinghui Lyu, Guofu Zhang, Chengrong Ding
      Pages: 1 - 5
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      A mild, simple process for the effective aerobic oxidative deoximation of a wide range of ketoximes and aldoximes has been developed that utilizes Fe(NO3)3·9H2O as the single catalyst and molecular oxygen as the green oxidant. The environmentally benign protocol provides moderate to excellent yield and broad functional groups tolerance and is a valuable synthetic method for practical applications. According the relevant verification experiment, a plausible mechanism has been proposed.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-04-24T07:00:00Z
      DOI: 10.1139/cjc-2017-0567
       
  • Preparation and characterization of apatite-like compound
    • Authors: Khaled Boughzala, Ali Bechrifa, Fethi Kooli, Nabil Fattah, Khaled Bouzouita
      Pages: 1 - 7
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Barium–lanthanum britholite solid solutions, Ba10-xLax(PO4)6-x(SiO4)xF2, with 0 ≤ x ≤ 6 were prepared by solid state reaction in the temperature range of 1200–1400 °C. The powders were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), F-selective electrode, X-ray diffraction (XRD), and Fourier transform infrared (FTIR). In addition, the present study used thermal analysis to follow the apatite formation reaction during the heat treatment. For x ≤ 3, there is formation of a single apatite phase, whereas above this value, the La2SiO5, La2Si2O7, BaSi2O5, and Ba2La2O5 secondary phases were observed. The variation of the lattice parameters of the apatite phase as a function of x confirmed that the solid solution is discontinuous to either side of x = 3.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-04-19T07:00:00Z
      DOI: 10.1139/cjc-2017-0459
       
  • A rapid and sensitive IC-ICP-MS method for determining selenium speciation
           in natural waters
    • Authors: Mark W. Donner, Tariq Siddique
      Pages: 1 - 8
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Selenium (Se) is an element monitored by water quality agencies worldwide. The challenge of assessing its presence in aquatic systems is its low concentrations (parts per trillion) and the need for determining its chemical speciation. A method was developed using an ion chromatograph (IC) paired with a quadrupole inductively coupled plasma mass spectrometer (ICP-MS) equipped with a hydrogen reaction cell to provide analysts with a rapid and sensitive method to measure Se speciation with suitable accuracy and precision. The Se species selenite (SeIV) and selenate (SeVI) were separated within a 5 min span using dilute nitric acid as a mobile phase in a step-wise gradient (50–400 mmol L−1) and quantified using 80Se isotope that yielded low limits of detection (
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-04-10T07:00:00Z
      DOI: 10.1139/cjc-2017-0637
       
  • Resolving the effects of compositional change on structures in Cu2ZnSnS4
           nanocrystals by X-ray absorption fine structure
    • Authors: Matthew J. Turnbull, Saghar Khoshmashrab, Yun Mui Yiu, Zhifeng Ding
      Pages: 1 - 10
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Renewable energy sources, and solar energy in particular, are a high impact research topic in the push for sustainable, long-term energy alternatives to fossil fuels. Cu2ZnSnS4 (CZTS) is one of the attractive, cost-effective materials that meets these needs. The quaternary nature makes the structure prone to defects and crystal alignment disorder. Some of these defects create advantageous electronic effects through antisite substitutions of Zn for Cu, [math]. Others such as Sn for Zn replacements are detrimental. Synchrotron-based X-ray absorbance fine structure (XAFS) analysis was used to identify specific patterns in the antisite contributions to the structure of low-cost CZTS films that produced the highest photoresponse in each of our samples. Correlations were found between the Cu/(Zn + Sn) ratio and advantageous antisite formations, though at the cost of increased alignment disorder. Similarly, the Zn/Sn ratio showed relationships between both advantageous and disadvantageous antisite and vacancy pairs. Variations in the local surroundings for each metal center were confirmed through X-ray absorption near-edge structures (XANES). Extended X-ray absorption fine structures (EXAFS), verified through FEFF fitting of the EXAFS, confirmed the patterns in crystal alignment disorder, and the effects each antisite had on the overall crystal structure. The precision and unique nature of such synchrotron techniques offers opportunities to identify these trends at each metal center, providing guidance to balance negative and positive structural components during fabrication. Each minor change in stoichiometry has been shown to affect several interactions within the structure.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-03-21T07:00:00Z
      DOI: 10.1139/cjc-2017-0697
       
  • An engineered one-site aptamer with higher sensitivity for label-free
           detection of adenosine on graphene oxide
    • Authors: Zijie Zhang, Juewen Liu
      Pages: 1 - 7
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      The 27-nucleotide DNA aptamer for adenosine and ATP, originally selected by the Szostak lab in 1995, has been a very popular model system for biosensor development. This unique aptamer has two target binding sites, and we recently showed that it is possible to remove either site while the other one still retains binding. From an analytical perspective, tuning the number of binding sites has important implications in modulating sensitivity of the resulting biosensors. In this work, we report that the engineered one-site aptamer showed excellent signaling properties with a 2.6-fold stronger signal intensity and also a 4.2-fold increased detection limit compared with the wild-type two-site aptamer. The aptamer has a hairpin structure, and the length of the hairpin stem was systematically varied for the one-site aptamers. Isothermal titration calorimetry and a label-free fluorescence signaling method with graphene oxide and SYBR Green I were respectively used to evaluate binding and sensor performance. Although longer stemmed aptamers produced better adenosine binding affinity, the signaling was quite independent of the stem length as long as more than three base pairs were left. This was explained by the higher affinity of binding to GO by the longer aptamers, cancelling out the higher affinity for adenosine binding. This work further confirms the analytical applications of such one-site adenosine aptamers, which are potentially useful for improved ATP imaging and for developing new biosensors.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-02-07T08:00:00Z
      DOI: 10.1139/cjc-2017-0601
       
  • Investigation of the push–pull effects on β-functionalized zinc
           porphyrin coordinated to C60 donor–acceptor conjugates
    • Authors: Michael B. Thomas, R.G. Waruna Jindasa, Yi Hu, Benjamin Schmitz, Hong Wang, Francis D’Souza
      Pages: 1 - 9
      Abstract: Canadian Journal of Chemistry, e-First Articles.
      Two novel β-functionalized push–pull zinc porphyrins with amine or phenyl push-groups and cyclic imide or carboxylic esters pull-groups have been newly synthesized for light energy harvesting applications. The ethynylphenyl spacers extended the conjugation of the porphyrin π-systems, as reflected by their red-shifted absorbance and fluorescence spectra. Computational studies performed at the B3LYP/6-31G* level indicated no steric hindrance between the porphyrin π-system and the substituents. The calculated HOMO and LUMO orbitals displayed significant delocalization in 1, where the electron density in the HOMO was localized over the push groups, whereas the LUMO was extended over the porphyrin π- and pull-groups. On the other hand, 2 did not display significant orbital segregation, which is attributed to its weaker push–pull character. Electrochemical studies revealed smaller HOMO–LUMO gaps for the push–pull zinc porphyrins. As a consequence of the push–pull effects, reduction in fluorescence intensity and lifetime was observed. Femtosecond transient absorption spectral studies revealed successful formation of singlet excited state in both of the push–pull porphyrins. Donor–acceptor conjugates were subsequently built and characterized by coordinating an electron acceptor, C60Im, via metal–ligand axial coordination. Efficient photo-induced charge separation in both donor–acceptor conjugates was witnessed wherein the charge-separated states persisted tens of nanoseconds prior returning to the ground state.
      Citation: Canadian Journal of Chemistry
      PubDate: 2018-01-23T08:00:00Z
      DOI: 10.1139/cjc-2017-0416
       
 
 
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