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  Subjects -> CHEMISTRY (Total: 838 journals)
    - ANALYTICAL CHEMISTRY (48 journals)
    - CHEMISTRY (587 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (26 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (46 journals)
    - PHYSICAL CHEMISTRY (68 journals)

CHEMISTRY (587 journals)            First | 1 2 3 4 5 6 | Last

Fitoterapia     Hybrid Journal   (Followers: 4)
Fluid Phase Equilibria     Hybrid Journal   (Followers: 2)
Fluorescent Materials     Open Access  
Folia Histochemica et Cytobiologica     Open Access  
Folia Microbiologica     Hybrid Journal   (Followers: 1)
Food Digestion     Hybrid Journal   (Followers: 4)
Food Security     Hybrid Journal   (Followers: 7)
Food Structure     Hybrid Journal  
Foundations of Chemistry     Hybrid Journal   (Followers: 2)
Frontiers in Chemistry     Open Access   (Followers: 1)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Frontiers of Chemistry in China     Hybrid Journal   (Followers: 2)
Fullerenes, Nanotubes and Carbon Nanostructures     Hybrid Journal   (Followers: 5)
Fundamentals of Interface and Colloid Science     Full-text available via subscription   (Followers: 6)
Future Medicinal Chemistry     Full-text available via subscription   (Followers: 4)
Gels     Open Access  
Geochemical Transactions     Open Access   (Followers: 3)
GFF     Hybrid Journal  
Glycobiology Insights     Open Access   (Followers: 1)
Graphene     Open Access   (Followers: 10)
Graphene     Full-text available via subscription  
Green and Sustainable Chemistry     Open Access   (Followers: 3)
Green Chemistry Letters and Reviews     Open Access   (Followers: 4)
Green Processing and Synthesis     Hybrid Journal   (Followers: 1)
Handbook of Exploration and Environmental Geochemistry     Full-text available via subscription   (Followers: 1)
Handbook of Exploration Geochemistry     Full-text available via subscription  
Handbook of Surface Science     Full-text available via subscription   (Followers: 3)
Handbook of Vapor Pressure     Full-text available via subscription  
Helvetica Chimica Acta     Hybrid Journal   (Followers: 9)
Heritage Science     Open Access   (Followers: 4)
Heteroatom Chemistry     Hybrid Journal   (Followers: 2)
High Energy Chemistry     Hybrid Journal  
Hydrogels     Open Access  
Indian Chemical Engineer     Hybrid Journal   (Followers: 3)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 12)
Indian Journal of Chemistry - Section B (IJC-B)     Open Access   (Followers: 5)
Indian Journal of Natural Products and Resources (IJNPR)     Open Access   (Followers: 3)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 9)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 4)
Inorganic Chemistry     Full-text available via subscription   (Followers: 20)
Inorganic Chemistry Communications     Hybrid Journal   (Followers: 8)
Inorganic Materials     Hybrid Journal   (Followers: 2)
Inorganica Chimica Acta     Hybrid Journal   (Followers: 4)
Instrumentation Science & Technology     Hybrid Journal   (Followers: 3)
International Archives of Science and Technology     Open Access  
International Journal for Ion Mobility Spectrometry     Hybrid Journal   (Followers: 1)
International Journal of Adhesion and Adhesives     Hybrid Journal   (Followers: 14)
International Journal of Advanced Chemistry     Open Access  
International Journal of Analytical Mass Spectrometry and Chromatography     Open Access   (Followers: 2)
International Journal of Bioassays     Open Access   (Followers: 6)
International Journal of Biological and Chemical Sciences     Open Access   (Followers: 2)
International Journal of Biological Chemistry     Open Access   (Followers: 4)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 7)
International Journal of Carbohydrate Chemistry     Open Access   (Followers: 7)
International Journal of Chemical and Analytical Science     Full-text available via subscription   (Followers: 5)
International Journal of Chemical and Life Sciences     Open Access   (Followers: 3)
International Journal of Chemical Kinetics     Hybrid Journal   (Followers: 4)
International Journal of Chemical Technology     Open Access   (Followers: 4)
International Journal of Chemistry     Open Access   (Followers: 7)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Corrosion     Open Access   (Followers: 11)
International Journal of High Throughput Screening     Open Access   (Followers: 2)
International Journal of Materials and Chemistry     Open Access   (Followers: 6)
International Journal of Medicinal Chemistry     Open Access   (Followers: 7)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 8)
International Journal of Molecular Imaging     Open Access   (Followers: 1)
International Journal of Molecular Sciences     Open Access   (Followers: 1)
International Journal of Nano Dimension     Open Access   (Followers: 2)
International Journal of Nonferrous Metallurgy     Open Access   (Followers: 2)
International Journal of Photochemistry     Open Access   (Followers: 1)
International Journal of Photoenergy     Open Access   (Followers: 2)
International Journal of Physical Sciences     Open Access  
International Journal of Spray and Combustion Dynamics     Full-text available via subscription   (Followers: 6)
International Journal of Tryptophan Research     Open Access  
Iranian Polymer Journal     Hybrid Journal   (Followers: 4)
Israel Journal of Chemistry     Full-text available via subscription   (Followers: 2)
JBIC Journal of Biological Inorganic Chemistry     Hybrid Journal   (Followers: 3)
JCP : BioChemical Physics     Hybrid Journal   (Followers: 1)
JOT Journal für Oberflächentechnik     Hybrid Journal  
JOT-International Surface Technology     Hybrid Journal   (Followers: 1)
Journal of Chromatography & Separation Techniques     Open Access   (Followers: 8)
Journal of Thermodynamics & Catalysis     Open Access   (Followers: 3)
Journal of Adhesion     Hybrid Journal   (Followers: 7)
Journal of Adhesion Science and Technology     Hybrid Journal   (Followers: 7)
Journal of Advanced Oxidation Technologies     Full-text available via subscription   (Followers: 1)
Journal of Advances in Chemistry     Open Access   (Followers: 4)
Journal of Agricultural and Food Chemistry     Full-text available via subscription   (Followers: 17)
Journal of Agricultural Chemistry and Environment     Open Access  
Journal of Amino Acids     Open Access   (Followers: 3)
Journal of Analytical Sciences, Methods and Instrumentation     Open Access   (Followers: 1)
Journal of AOAC International     Full-text available via subscription   (Followers: 8)
Journal of Applied Chemistry     Open Access   (Followers: 2)
Journal of Applied Solution Chemistry and Modeling     Hybrid Journal  
Journal of Applied Spectroscopy     Hybrid Journal   (Followers: 7)
Journal of Argentine Chemical Society     Open Access  
Journal of Automated Methods and Management in Chemistry     Open Access  
Journal of Biomaterials and Nanobiotechnology     Open Access   (Followers: 5)
Journal of Carbohydrate Chemistry     Hybrid Journal   (Followers: 5)
Journal of Catalysis     Hybrid Journal   (Followers: 6)
Journal of Catalyst & Catalysis     Full-text available via subscription  

  First | 1 2 3 4 5 6 | Last

Journal Cover   Journal of Theoretical and Computational Chemistry
  [SJR: 0.364]   [H-I: 17]   [8 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0219-6336 - ISSN (Online) 1793-6888
   Published by World Scientific Homepage  [120 journals]
  • Calculation of free energy changes due to mutations from alchemical free
           energy simulations
    • Authors: M. Harunur Rashid, Germano Heinzelmann, Serdar Kuyucak
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      How a mutation affects the binding free energy of a ligand is a fundamental problem in molecular biology/biochemistry with many applications in pharmacology and biotechnology, e.g. design of drugs and enzymes. Free energy change due to a mutation can be determined most accurately by performing alchemical free energy calculations in molecular dynamics (MD) simulations. Here we discuss the necessary conditions for success of free energy calculations using toxin peptides that bind to ion channels as examples. We show that preservation of the binding mode is an essential requirement but this condition is not always satisfied, especially when the mutation involves a charged residue. Otherwise problems with accuracy of results encountered in mutation of charged residues can be overcome by performing the mutation on the ligand in the binding site and bulk simultaneously and in the same system. The proposed method will be useful in improving the affinity and selectivity profiles of drug leads and enzymes via computational design and protein engineering.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Fri, 17 Apr 2015 02:57:46 GMT
      DOI: 10.1142/S0219633615500236
       
  • A chromium carbene (OC)5Cr=C(OEt)(–C≡C–Ph): Quantum
           mechanical study of molecular structure, HOMO–LUMO analysis, IR
           spectroscopy, natural bond orbital analysis
    • Authors: Reza Ghiasi
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      In this work, the structural, electronic properties, 13C and 1H NMR parameters and first hyperpolarizability of a chromium carbene (OC)5Cr=C(OEt)(–C≡C–Ph) complex were theoretically computed in gas phase and different solvents. Also, the solvent effect on structural parameters, frontier orbital energies, –C≡C– and C≡O stretching frequencies of complex has been carried out based on polarizable continuum model (PCM). The results indicate that the polarity of solvents has played a significant role on the structures and properties of complex. 1H and 13C NMR chemical shifts were calculated by using the gauge-independent atomic orbital (GIAO) method. In analyzing the structural characteristics of this structure, Cr–CO and Cr–Ccarbene bonds were identified and characterized in detail by topological parameters such as electron density ρ(r) and Laplacian of electron density ∇2ρ(r) from Bader's atom in molecules theory.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Wed, 08 Apr 2015 01:45:48 GMT
      DOI: 10.1142/S0219633615500224
       
  • AIM and NBO analyses on the interaction between SWCNT and cyclophosphamide
           as an anticancer drug: A density functional theory study
    • Authors: Zahra Felegari, Majid Monajjemi
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      In this work, the molecular structures of single-walled carbon nanotube (SWCNT), cyclophosphamide and cyclophosphamide–SWCNT complex were optimized B3LYP/6-31G* level of theory. The nanotube used in this study was a (5,5) SWCNT including 150 C atoms. The NBO analysis showed that the transfer electron can be occurred from the lone pair of oxygen (donor atom) in the cyclophosphamide to the σ* or π* orbitals of the carbon atoms (acceptor atoms) in the SWCNT. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and energy gap (HOMO–LUMO) were calculated for the studied structures and the results indicated the stability of the complex. In addition, the calculated chemical shift isotropy (σ) and the chemical shift anisotropy (Δσ) confirmed the interaction between cyclophosphamide and SWCNT. Also, the results of the atoms in molecule (AIM) theory indicated that the H145–O164 bond is a partial covalent bond.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Mon, 06 Apr 2015 07:59:39 GMT
      DOI: 10.1142/S0219633615500212
       
  • First principle simulation on oxidation mechanism of diethyl ether by
           nitrogen dioxide
    • Authors: Yuan Yuan, Wei Hu, Xuhui Chi, Cuihua Li, Dayong Gui, Mingliang Wang, Jianhong Liu, Xingang Ma, Aimin Pang
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      The oxidation mechanism of diethyl ethers by NO2 was carried out using density functional theory (DFT) at the B3LYP/6-31+G (d, p) level. The oxidation process of ether follows four steps. First, the diethyl ether reacts with NO2 to produce HNO2 and diethyl ether radical with an energy barrier of 20.62 kcal ⋅ mol-1. Then, the diethyl ether radical formed in the first step directly combines with NO2 to form CH3CH(ONO)OCH2CH3. In the third step, the CH3CH(ONO)OCH2CH3 was further decomposed into the CH3CH2ONO and CH3CHO with a moderately high energy barrier of 32.87 kcal ⋅ mol-1. Finally, the CH3CH2ONO continues to react with NO2 to yield CH3CHO, HNO2 and NO with an energy barrier of 28.13 kcal ⋅ mol-1. The calculated oxidation mechanism agrees well with Nishiguchi and Okamoto's experiment and proposal.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Mon, 06 Apr 2015 07:59:38 GMT
      DOI: 10.1142/S0219633615500200
       
  • Multistep reactions of water with small Pdn clusters: A first principles
           study
    • Authors: Yanhua Liang, Li Ma, Jianguang Wang, Guanghou Wang
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      Multistep dissociative chemisorption reactions of water with Pd4 and Pd7 clusters were studied using density functional theory. The adsorption energies and referred adsorption sites from water molecule (H2O) to partially dissociative (H2+O and OH+H), then to fully dissociative (O+H+H) configurations are carefully determined. It is found that the adsorption energies of three dissociative reactions are 5–6 times larger than that of water molecule. Atop sites of Pd4 and Pd7 clusters are found to be the most stable sites for the adsorbed H2O molecule. For the coadsorption cases of partially and fully dissociated products, H2 and OH molecules preferably tend to bind at the low coordination (atop or bridge) sites, and O and H atoms prefer to adsorb on the high coordination (hollow) sites. It is also found that the most favorable adsorption sites for the molecular adsorbates (H2O, H2 and OH) are adjacent to the Pd atoms with the largest site-specific polarizabilities. Therefore, site-specific polarizability is a good predictor of the favorable adsorption sites for the weakly bound molecules. The different directions of charge transfer between the Pd clusters and the adsorbate(s) is observed. Furthermore, the processes of the adsorption, dissociation, and the dissociative products diffusion of H2O are analyzed.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Thu, 19 Mar 2015 07:12:51 GMT
      DOI: 10.1142/S0219633615500170
       
  • Investigation on the photodriven catalytic coupling reaction mechanism of
           p-aminothiophenol on the silver cluster
    • Authors: Lai-Cai Li, Wei Wang, Dan Peng, Rui Pan, An-Min Tian
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      The catalytic coupling reaction mechanism for the transformation from p-aminothiophenol (PATP) to 4,4′-dimercaptoazobenzene (4,4′-DMAB) on silver cluster was studied by the density functional theory. All the reactants, intermediates, transition states and products were optimized with B3LYP method at 6-311+G (d, p) basis set (the LanL2DZ basis set was used for Ag atom). Transition states and intermediates have been confirmed by the corresponding vibration analysis and intrinsic reactions coordinate (IRC). In addition, nature bond orbital (NBO) and atoms in molecules (AIM) theories have been used to analyze orbital interactions and bond natures. Consistent with the conclusions reported in the literature, the core of obtaining the production of azobenzene according to the coupling reaction of PATP absorbed on Ag5 clusters is the elimination of two H atoms. Meanwhile, we find that the effect of illumination in that reaction matters a lot. We also found in PATP molecular that the synergistic catalytic effect of S end absorbed on the catalyzer draws dramatically evident under no illumination conditions, while it draws less obvious under light. According to the paper's conclusion, PATP absorbed on the surface of Ag5 tends to generate azobenzene easily.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Thu, 19 Mar 2015 07:12:50 GMT
      DOI: 10.1142/S0219633615500194
       
  • Benzimidazole derivatives as anticancer drugs: A theoretical investigation
    • Authors: Davood Farmanzadeh, Meysam Najafi
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      In this study the anticancer properties of a series of benzimidazole drugs 1–9 and their interactions with DNA base pairs were investigated. The obtained theoretical results for anticancer activity of synthesized drugs 1–5 were compared to corresponding published experimental results. Based on theoretical and published experimental anticancer scales, drugs 2 and 4 have higher anticancer activity among drugs 1–5. Obtained results reveal that interactions of studied drugs with DNA base pairs are energetically favorable and solvent and electric field (EF) increase the binding energies in comparison to gas phase. The binding energies of drugs 2, 5 and 4 with DNA base pairs are more negative than corresponding values for drug 1. We propose the novel drugs 6–9 to synthesize with higher anticancer activity. Results show that binding energies of novel drugs 6–9 were more negative than drugs 1–5. Finally, results show that chemical potential, electrophilicity and global hardness can be considered as admissible theoretical anticancer indexes for studied benzimidazole drugs 1–9.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Thu, 19 Mar 2015 07:12:49 GMT
      DOI: 10.1142/S0219633615500182
       
  • Toward understanding tautomeric switching in 4-hydroxynaphthaldehyde and
           its dimers: A DFT and quantum topology study
    • Authors: Aeshah El-Amri, Shaaban A. Elroby, Oliver Kühn, Rifaat H. Hilal
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      The electronic structures and stabilities of all benzenoid (enol) and quinonoid (keto) forms of 4-hydroxynaphthaldehyde (ALD-14) have been investigated using density functional theory (DFT) with a range of functionals and basis sets. The anti-enol form represents the global minimum energy structure. Low rotation barriers of both the hydroxyl and the aldehyde groups characterize this form. Fourier analysis of the potential energy function for rotation indicate that the conformational preference of ALD-14 is determined by both the dipole–dipole repulsion and bond moments interactions. Further, three different ALD-14 dimer complexes are investigated, i.e. head-to-tail (HT), head-to-head (HH), and stacked (S) forms. The analysis of natural bond order, quantum topology features of the Laplacian of the electron density, binding energies and structural parameters of these dimers point to comparable stabilities of the HT and S-dimers, with a preference for a stacking contact. The origin of its stability can be traced to π-conjugative, H-bonding and dispersion interactions.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Thu, 19 Mar 2015 07:12:49 GMT
      DOI: 10.1142/S0219633615500169
       
  • Electronic structures of hexane isomers studied using quantum mechanics
           and graph theory
    • Authors: Subhojyoti Chatterjee, Feng Wang
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      Electronic and topological properties of hexane (C6H14) and its five geometric isomers are systematically studied quantum mechanically using several techniques such as positron–electron annihilation gamma-ray spectra, C1s binding energy spectra and carbon nuclear magnetic resonance (NMR) spectra, as well as information derived from graph theory. It is revealed that the Doppler-shift in the gamma-ray spectra of the hexane isomers is in the vicinity of the n-hexane molecule with small structural dependency, in agreement with the fact that the measured Doppler-shifts of other linear alkanes are in the vicinity of hexane. The present study further reveals the electronic structures of hexane isomers, which are deeply rooted into the carbon core electrons, more than mere properties in the valence space. The calculations show that the highest occupied molecular orbitals (HOMOs) of the isomers exhibit less important roles in gamma-ray spectra; whereas the electron–positron annihilation is dominated by the electrons of the lowest occupied valence orbitals (LOVOs) and other valence electrons underneath the HOMO electrons, in agreement with previous findings. The present study further reveals that the C1s binding energies of the isomers exhibit association with the nodes of the isomers using graph theory. That is, more branched carbons likely engage with larger chemical shift, which is indicated by the largest eigenvalues (LEVs) of the adjacency matrix (AM) from graph theory. The chemical shift of the carbon NMR spectra is revealed by the LEVs of the Laplacian matrix (LM) obtained from chemical graph theory.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Fri, 06 Mar 2015 01:41:11 GMT
      DOI: 10.1142/S0219633615500145
       
  • Effect of electronic excitation to intermolecular proton transfer in bulk
           nitromethane: Tuned parameter SCC-DFTB and first principles study
    • Authors: Feng Guo, Hong Zhang, Chao-Yang Zhang, Xin-Lu Cheng, Hai-Quan Hu
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      To understand the reaction mechanism involving hydrogen transfers through hydrogen-bond bridge, we carried out both Self-Consistent Charge Density Functional Tight-Binding (SCC-DFTB) calculations of bulk nitromethane and Density Functional Theory (DFT) calculations of singlet ground state/triplet excited state molecular nitromethane using B3LYP functional. Firstly, we tuned the repulsive parameters of the SCC-DFTB method for nitromethane with dataset calculated from DFT at B3LYP/6-311g level. The molecular dynamics simulations are carried out with tuned parameters to get the dynamical properties of the bulk nitromethane, and the static calculations are intended to give energy profile of the reaction process. These calculations indicate the excitation of nitromethane molecule making the proton transfer reactions possible, and lowering the reaction barrier.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Wed, 04 Mar 2015 07:09:41 GMT
      DOI: 10.1142/S0219633615500133
       
  • Water molecules response to an external GHz electric field in KcsA
           potassium channel: A molecular modeling approach
    • Authors: M. Sajadi, A. Lohrasebi, S. S. Setayandeh, H. Rafii-Tabar
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      KcsA potassium channel is a membrane protein that allows the passage of potassium ions and water molecules across the cellular membrane. Using molecular dynamics (MD) simulation method, the effect of an applied GHz oscillating electric field of strength 0.004 V/nm on the dynamics of K+ and water molecules in a KcsA channel was modeled. It was found that the application of GHz range electric field caused a change in the potential energy profile of the water molecules in the filter sites, causing an increase in the delay time of the water molecules in these sites. Therefore, exposing the channel to the GHz fields can perturb the dynamics of the water molecules in the filter, and consequently, the channel operation may be disturbed. Furthermore, the results show that the applied field has no major effects on the dipole orientation of water molecules in the channel.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Thu, 26 Feb 2015 02:44:02 GMT
      DOI: 10.1142/S0219633615500121
       
  • Adsorption of 2-vinyl thiophene on Si(100)2 × 1: A van Der Waals
           corrected DFT study
    • Authors: Marilena Carbone
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      Oligo- and polythiophenes on surfaces play a fundamental role in building molecular circuits and organic-based electronics and may be assembled via interaction of the monomer units with the surface. In this framework, the nature of interaction of 2-vinyl thiophene (2VTP), a conjugated heteroaromatic monomer unit, with the Si(100) surface was studied by means of density functional theory (DFT). In particular, structural optimizations were performed comparing the effects of the inclusion of van der Waals (VdW) forces. It came out that the adsorption through the double bond is energetically favored, if VdW forces are included, whereas the adsorption through both aromatic ring and double bond simultaneously is more stable, if they are excluded. Physisorbed states were singled out and the barriers between two of them and the corresponding chemisorbed states were calculated along with the imaginary frequencies of the transition states. Also the transition energies have different values if the VdW forces are included.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Wed, 11 Feb 2015 07:12:41 GMT
      DOI: 10.1142/S021963361550011X
       
  • Theoretical investigation of an atmospherically important reaction between
           methyl methacrylate and Cl atom: A mechanistic and kinetic approach
    • Authors: Partha Biswas
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      A theoretical investigation of the mechanism, kinetics and probable product analysis of the Cl-initiated oxidation reaction of methyl methacrylate (MMA) is presented in this paper. The major degradation pathway of MMA is the Cl-addition to the terminal carbon of the olefinic bond. Beside this, energetic and mechanism of other possible reaction pathways are discussed in detail. In addition, the mechanism for the secondary reactions in presence of O2 and NO has also been presented. Cl-addition to the double bond takes place via formation of the pre-reactive complex as these reaction channel passes through negative activation barrier. Energetics and thermochemical analysis have been studied at the MP2=Full/6-311++g(d,p) level of theory. The rate constant of the Cl-addition reaction has been calculated using conventional transition state theory (CTST) at 1 atm pressure and 250–350 K temperature range.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Fri, 06 Feb 2015 01:40:33 GMT
      DOI: 10.1142/S0219633615500108
       
  • Computational comparison of reactions of CS2 with CHX•- (X = F, Cl,
           and Br): Do F, Cl, and Br substitutions effect differently?
    • Authors: Junxi Liang, Qiong Su, Shijie Zheng, Jing Yu, Zhiyuan Geng
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      Calculations based on density functional theory (DFT) have been carried out for the gas-phase ion-molecule reactions of CS2 with CHX•- (X = F, Cl, and Br) to investigate the effect of the halogen-substituent on the reaction mechanism. The doublet potential energy surfaces (PESs), involving two striking reaction patterns named by the middle-C attack and the end-S attack in terms of anion attack on the C and S atoms of CS2, have been explored and characterized in detail. Compared with the results of the end-S attack, reaction with the middle-C attack pattern displays more efficiency on PES. For a given reaction pattern, the reactions of CHCl•- and CHBr•- occur with similar efficiencies and reactivity trends. The CHF•- anion displays remarkably different reactivity, which is traced to its lower electron binding energy and the effect of the electronegative fluorine substituent. This is in good agreement with the experimental observation. According to the property of the product branching ratios in experiment, dynamical effect is used to evaluate the reason that the end-S attack with less energetically favorable obtained in our theoretical studies is comparable to the middle-C attack.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Wed, 04 Feb 2015 07:15:17 GMT
      DOI: 10.1142/S0219633615500091
       
  • The mechanisms of α-H and proton transfers of glycine induced by Mg2+
    • Authors: Qing Zhang, Xiang-Jun Meng
      Abstract: Journal of Theoretical and Computational Chemistry, Ahead of Print.
      A MP2/6-31++G(d,p)//B3LYP/6-31++G(d,p) method was used to investigate the mechanisms of α-H and proton transfers of glycine induced by Mg2+. Eight complexes were obtained, six of which were neutral and the other two were zwitterionic. Among them, the zwitterion with a binding energy of 159.4 kcal/mol was the most stable structure. Conformation transformations of the complexes caused by the rotation of single bond and the transfers of α-H and proton were completed via seven transition states. The inductive effect of Mg2+ made the electron cloud of glycine deviate to Mg2+, which activated the covalent bond involving the transferred proton. The neutral complex can be turned into the zwitterionic one by the transfers of both carboxyl hydrogen and α-H, and the energy barrier of each reaction was less than 9.2 kcal/mol. After the transfer of α-H, a delocalized π bond was formed in glycine skeleton and the α-C atom took 0.19 positive charges. So the chemical activity of the glycine enhanced, and glycine was readily available for addition and nucleophilic substitution reactions. The path from the most stable glycine conformer G1 to the zwitterionic conformation I is G1 → G1–G3 → G3 → G3–G4 → G4 → G2–G4 → G2 → VI → I–VI → I, and the highest energy barrier of this path is 9.2 kcal/mol.
      Citation: Journal of Theoretical and Computational Chemistry
      PubDate: Fri, 30 Jan 2015 09:16:02 GMT
      DOI: 10.1142/S021963361550008X
       
 
 
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