Theoretical study with DFT on the mechanism of visible light-driven β-functionalization of aldehydes
We present results of density functional theory (DFT) study on the mechanism of photo-organocatalytic β-functionalization of aldehydes with Michael acceptors. The plausible mechanism afforded involves three distinct steps: radical generation, radical addition, oxidative hydrogen atom transfer. The region-determining step is the radical addition step which affords α- or β-radical addition adduct through α-/β-transition states with different barrier. In the reduction step of radical addition adduct, the calculation results support our proposal that oxidative hydrogen atom transfers (HAT) from enami...
Source: Computational and Theoretical Chemistry - December 6, 2017 Category: Chemistry Source Type: research

Quantum dynamics calculations for e+  + LiH → Li+ + [H−; e+] dissociative positron attachment using a pseudopotential model
Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): Kento Suzuki, Toshiyuki Takayanagi, Yukiumi Kita, Masanori Tachikawa, Takayuki Oyamada We theoretically discuss the dynamics of the chemical reaction process induced by positron attachment, e + + LiH → Li+ + [H−; e +]. Simple model pseudopotentials were developed on the basis of the electrostatic interaction between e + and LiH with a large dipole moment, where some numerical parameters were chosen to qualitatively reproduce the previous-reported ab initio positron-bound adiabatic potential ener...
Source: Computational and Theoretical Chemistry - December 6, 2017 Category: Chemistry Source Type: research

An alternative approach to structural analysis for gas electron diffraction method
Publication date: Available online 1 December 2017 Source:Computational and Theoretical Chemistry Author(s): Yu.A. Zhabanov, A.E. PogoninGraphical abstract (Source: Computational and Theoretical Chemistry)
Source: Computational and Theoretical Chemistry - December 2, 2017 Category: Chemistry Source Type: research

Quantum dynamics calculations for e+ + LiH → Li+ + [H−; e+] dissociative positron attachment using a pseudopotential model
Publication date: Available online 1 December 2017 Source:Computational and Theoretical Chemistry Author(s): Kento Suzuki, Toshiyuki Takayanagi, Yukiumi Kita, Masanori Tachikawa, Takayuki Oyamada We theoretically discuss the dynamics of the chemical reaction process induced by positron attachment, e + + LiH → Li+ + [H−; e +]. Simple model pseudopotentials were developed on the basis of the electrostatic interaction between e + and LiH with a large dipole moment, where some numerical parameters were chosen to qualitatively reproduce the previous-reported ab initio positron-bound adiabatic potential energy curve ...
Source: Computational and Theoretical Chemistry - December 2, 2017 Category: Chemistry Source Type: research

Information entropy changes in chemical reactions
Publication date: Available online 2 December 2017 Source:Computational and Theoretical Chemistry Author(s): Denis Sh. Sabirov Currently, information entropy is used mainly for the description of the complexity of chemical structures. Recent advances in its application to fullerenes and interstellar compounds revealed that it could provide valuable information about chemical processes taking place under extreme conditions. We have applied the known Karreman’s algorithm to calculating information entropies of chemical reactions. This algorithm implies that information entropy of molecular ensemble equals the sum of t...
Source: Computational and Theoretical Chemistry - December 2, 2017 Category: Chemistry Source Type: research

Tandem Cope-rearrangement and [2+2] cycloaddition of cis-1,2-diethynylcyclopropane and its mono-hetero analogues: A DFT investigation
Publication date: Available online 2 December 2017 Source:Computational and Theoretical Chemistry Author(s): Manjinder Kour, Raakhi Gupta, R.K. Bansal Tandem Cope-rearrangement and [2+2] cycloaddition of cis-1,2-diethynylcyclopropane and its mono-hetero analogues (hetero atom: N, O, P) have been investigated in the gas phase at the B3LYP/6–31+G(d) level. The activation enthalpies for the Cope rearrangement of these compounds range from 24.18 to 29.60 kcal mol-1 which are 4-9 kcal mol-1 higher than those for the Cope rearrangement of the corresponding divinyl-analogues, which can be attributed to the cyclic strain be...
Source: Computational and Theoretical Chemistry - December 2, 2017 Category: Chemistry Source Type: research

Molecules as Networks: A Localization-Delocalization Matrices Approach
Publication date: Available online 23 November 2017 Source:Computational and Theoretical Chemistry Author(s): Chérif F. Matta Inspired by chemical graph theory (CGT), a matrix representation of molecules and reaction paths is presented within the framework of Bader’s quantum theory of atoms in molecules (QTAIM). A molecule is viewed as a network of electron delocalization channels or highways (vertices) that connect every pair of atoms in the system and electron localization cul-de-sacs loops connecting any given atom to itself. The representation of a molecule as a fuzzy, complete, non-directed graph, captur...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

Influence of CH4 and C3H8 molecules on stability of double-cage of sI clathrate hydrate
Publication date: Available online 28 November 2017 Source:Computational and Theoretical Chemistry Author(s): Ting An, Hui Zhang, Qiang Zhang, Yang Wang, Peng Shi Theoretical investigation on the stability of water cavities (512, 51262, and 512/51262) with the incorporation of a series of molecules (CH4 and C3H8) is accomplished. Geometry optimization for the guest molecules, host cages, and their complexes was carried out at B3LYP/6-31+G(d) level, and on the basis of the optimized geometry, single-point energy calculation was performed at M06-2X/6-31++G(d) level to determine the interaction and stability energies. The re...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

First-principles insights on detection of dimethyl amine and trimethyl amine vapors using graphdiyne nanosheets
Publication date: Available online 28 November 2017 Source:Computational and Theoretical Chemistry Author(s): V. Nagarajan, U. Srimathi, R. Chandiramouli The structural stability and electronic properties of zigzag graphdiyne nanosheet is studied using density functional theory (DFT) technique. The adsorption behavior of dimethyl amine (DMA) and trimethyl amine (TMA) vapor molecules on graphdiyne nanosheet are also investigated with DFT method. The density-of-states (DOS) spectrum gives the perception on charge transfer upon adsorption of DMA/TMA on graphdiyne nanosheet. The energy band gap changes upon the interaction of...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

Simulating Enzyme Reactivity: Computational Methods in Enzyme Catalysis, I. Tu ñón, V. Moliner (Eds.). The Royal Society of Chemistry Publishing, UK (2017)
Publication date: 15 December 2017 Source:Computational and Theoretical Chemistry, Volume 1122 Author(s): James W. Gauld (Source: Computational and Theoretical Chemistry)
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

A new free radical scavenging cascade involving melatonin and three of its metabolites (3OHM, AFMK and AMK)
Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): Miguel Reina, Ana Martínez Melatonin and three of its metabolites [cyclic 3-hydroxymelatonin (3OHM), N 1-acetyl-N 2-formyl-5-methoxykynuramine (AFMK) and N 1-acetyl-5-methoxykynuramine (AMK)] are investigated to analyze their antioxidant capacity. The sequential scavenging action of melatonin and these metabolites has been named an antioxidant cascade, which greatly increases capacity of melatonin to scavenge free radicals and, therefore, decrease oxidative damage. In this theoretical study, we identified a new a...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

Theoretical study: Electronic structure and receptor interaction of four type bis-1,4-dihydropyridine molecules
Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): G. Iván Vázquez Cisneros, José M. Vásquez-Pérez, Julián Cruz-Borbolla, Carlos Z. Gómez-Castro, M. Inés Nicolás-Vázquez, René Miranda Ruvalcaba The structure of four type bis-1,4-dihydropyridine molecules was completely optimized employing semiempirical (PM3), ab initio (HF/3-21G(d), B3LYP/6-31G(d) and B3LYP/6-311++G(d,p) methods. The B3LYP/6-311++G(d,p) theory level provided a flat boat conformation. The observed ring distortions were not found...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

Study of the structural, electronic, and optical properties of the host matrices of LiAl5O8 and LiGa5O8 via DFT
Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): Osmar M. de Sousa The structural, electronic, and optical properties of host matrices lithium aluminate spinel (LiAl5O8, LAO) and gallium lithium spinel (LiGa5O8, LGO) were analyzed based on calculations of the density functional theory. Optimizations of the crystal structures were performed using the generalized gradient approximation, while the electronic structure and optical properties were calculated using the modified Becke e Johnson potential. The calculated lattice parameters and atomic positions are in a good a...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

A theoretical study of the thermal stability of the FS(O2)OSO2 radical and the recombination kinetics with the FSO3 radical
Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): M.P. Badenes, C.J. Cobos, A.E. Croce The kinetics of the thermal reaction of FS(O2)OO(O2)SF with SO2 have been theoretically studied. Experimental investigations performed at 293–323 K indicate that the FSO3 radical, in equilibrium with the peroxide FS(O2)OO(O2)SF ⇄ 2 FSO3 (1, -1), initially attacks the SO2 forming the FS(O2)OSO2 radical which afterwards may dissociate back, FSO3 + SO2 ⇄ FS(O2)OSO2 (2, -2), or recombine with FSO3 generating the final product, FSO3 + FS(O2)OSO2 → (FS(...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

Molecular modeling reveals the inhibition mechanism and binding mode of ursolic acid to TLR4-MD2
Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): Xiaodi Niu, Yiding Yu, Hui Guo, Yanan Yang, Guizhen Wang, Lin Sun, Yawen Gao, Zhiling Yu, Hongsu Wang In the previous literature, it was reported that ursolic acid, a natural compound, can potently inhibit nuclear factor-kB by inhibiting the binding of LPS to the TLR4-MD2 complex. In this work, the inhibition mechanism of ursolic acid towards the TLR4-MD2 complex was explored using molecular dynamics simulations and binding free energy calculations. Molecular dynamics simulations revealed that ursolic acid can bind to t...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

Theoretical insight into CO-sensing performance of pure and oxygen-defective α-Fe2O3 (1 1 0) surface
Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): Feifei Li, Changmin Shi, Guangliang Cui, Dongchao Wang, Li Chen We carried out first-principle calculations with density functional theory to discuss adsorption properties, gas-sensing performance and mechanism of CO on pure and oxygen-defective α-Fe2O3 (1 1 0) surface. For pure and oxygen-defective α-Fe2O3 (1 1 0) surfaces, new formed CO2 acted as donors. The electron-transfer effects leaded to an increasing electron-carrier concentration, and resulted in a decreasing resistance of α-Fe2O3 (1...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

Mechanism of heterogeneous reaction between gaseous elemental mercury and H2O2 on Fe3O4 (1  1 0) surface
Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): Changsong Zhou, Hongmin Yang, Jiamin Chen, Dongxu Qi, Jiaxing Sun, Lin Mao, Zijian Song, Lushi Sun The Fe3O4 catalytic oxidation of gaseous elemental mercury (Hg0) has been regarded as a promising method to control mercury from flue gases given its high efficiency, magnetic separation, and recyclable properties. Density functional theory (DFT) calculations were performed to study the heterogeneous reaction mechanism between Hg0 and H2O2 over Fe3O4 (1 1 0) surface. The generation mechanism of surface hydroxyl on two ...
Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research

Theoretical insight into CO-sensing performance of pure and oxygen-defective α-Fe2O3 (1 1 0) surface
Publication date: Available online 15 November 2017 Source:Computational and Theoretical Chemistry Author(s): Feifei Li, Changmin Shi, Guangliang Cui, Dongchao Wang, Li Chen We carried out first-principle calculations with density functional theory to discuss adsorption properties, gas-sensing performance and mechanism of CO on pure and oxygen-defective α-Fe2O3 (1 1 0) surface. For pure and oxygen-defective α-Fe2O3 (1 1 0) surfaces, new formed CO2 acted as donors. The electron-transfer effects leaded to an increasing electron-carrier concentration, and resulted in a decreasing resistance of α-Fe2O3 (1 1 ...
Source: Computational and Theoretical Chemistry - November 17, 2017 Category: Chemistry Source Type: research

Theoretical study on DABCO-catalyzed ring expansion of cyclopropyl ketone: mechanism, chemoselectivity, and role of catalyst
Publication date: Available online 14 November 2017 Source:Computational and Theoretical Chemistry Author(s): Qianqian Shi, Yang Wang, Donghui Wei The possible mechanisms of 1,4-diazabicyclo[2.2.2]octane (DABCO)-catalyzed ring expansion of cyclopropyl ketone for forming dihydrofurans have been studied using density functional theory (DFT). According to the calculated results, the reaction occurs via two competing paths including paths A and B, which lead to two different products (i.e. 2-methyl-4,5-dihydrofuran and 2-phenyl-4,5-dihydrofuran), respectively. Path A is revealed to be more energetically favorable than path B,...
Source: Computational and Theoretical Chemistry - November 16, 2017 Category: Chemistry Source Type: research

Thermodynamic properties and stability of [B12Hx(CF3)12 −X]2− anion compex
In this study the thermodynamic properties of the dodecahydro-closo-dodecaborate anion B12H12 2− and its fluorinated derivatives, namely, B12Hx(CF3)12−x 2− (x = 9–12), have been calculated at the B3LYP-D3/6-311++G∗∗ level of theory. The calculated gas-phase heats of formation indicate the high thermodynamic stability of B12H12 2− anion complexes in which the hydrogen atoms are substituted by trifluoromethyl groups. Herewith, this stability increases with the increasing number of CF3 groups. According to Gibbs energy calculations, the formation of the B12Hx(CF3)12−x 2&mi...
Source: Computational and Theoretical Chemistry - November 14, 2017 Category: Chemistry Source Type: research

First-principles study of NO molecules adsorption on Ag-doped CuO(1  1 1) surface
Publication date: 15 December 2017 Source:Computational and Theoretical Chemistry, Volume 1122 Author(s): R.M. Hu, X.L. Zhou The surface structures, adsorption energies and electronic structures of NO molecules adsorbed on Ag-doped CuO(1 1 1) surface were investigated by using the density functional theory. The calculated results indicate that the Cu1-top site of the Ag-doped CuO(1 1 1) surface is the most favorable adsorption site for NO molecules. The adsorption energies of N atom as the adatom are greater than that of the O atom as the adatom. The high adsorption energy and short distance between NO and substra...
Source: Computational and Theoretical Chemistry - November 11, 2017 Category: Chemistry Source Type: research

Mechanism of heterogeneous reaction between gaseous elemental mercury and H2O2 on Fe3O4 (1 1 0) surface
Publication date: Available online 9 November 2017 Source:Computational and Theoretical Chemistry Author(s): Changsong Zhou, Hongmin Yang, Jiamin Chen, Dongxu Qi, Jiaxing Sun, Lin Mao, Zijian Song, Lushi Sun The Fe3O4 catalytic oxidation of gaseous elemental mercury (Hg0) has been regarded as a promising method to control mercury from flue gases given its high efficiency, magnetic separation, and recyclable properties. Density functional theory (DFT) calculations were performed to study the heterogeneous reaction mechanism between Hg0 and H2O2 over Fe3O4 (1 1 0) surface. The generation mechanism of surface hydroxyl on two...
Source: Computational and Theoretical Chemistry - November 10, 2017 Category: Chemistry Source Type: research

Dissociation mechanism of propane hydrate with methanol additive: a molecular dynamics simulation
Publication date: Available online 10 November 2017 Source:Computational and Theoretical Chemistry Author(s): Keyao Li, Ruili Shi, Yingying Huang, Lingli Tang, Xiaoxiao Cao, Yan Su, Jijun Zhao Employing NPT molecular dynamics method with consistent valence force field, dissociation processes of propane hydrate with and without methanol additive are simulated at different temperatures and a constant pressure of 50 MPa. We analyze structural snapshots, radial distribution functions, density distributions, angle distributions, change of energies, mean square displacements and diffusion coefficients of two comparative models ...
Source: Computational and Theoretical Chemistry - November 10, 2017 Category: Chemistry Source Type: research

Electron-based descriptors in the study of physicochemical properties of compounds
Publication date: Available online 8 November 2017 Source:Computational and Theoretical Chemistry Author(s): Vladimir Potemkin, Maria Grishina Recently invented AlteQ method for estimation of electron density of compounds was developed in the current work. AlteQ Slater-type electron density functions were approximated by Gaussians for fast estimation of electron overlaps. The obtained approach was named AlteQ-G. AlteQ-G 3D maps of electron density computed for organic and inorganic molecules were compared to the experimentally obtained high-resolution X-ray diffraction (HRXRD) data. Different electron-based characteristic...
Source: Computational and Theoretical Chemistry - November 9, 2017 Category: Chemistry Source Type: research

Neutral Noble Gas Compound with a Xenon-Metal Double Bond: a Theoretical Study of F2XeWF2
Publication date: Available online 7 November 2017 Source:Computational and Theoretical Chemistry Author(s): Kunqi Gao, Li Sheng The noble gas compound containing a double bond of xenon and transition metal atoms (i.e. F2XeWF2) is predicted by using quantum-chemical calculations. At the MP2 level of theory, the predicted Xe-W bond length of 2.45 Å is comparable to the corresponding standard double bond length of 2.55 Å (i.e. the sum of double bond radii of Xe and W atoms). Natural bond orbital analysis indicates that the Xe-W double bond consists of a σ-bond and a π-bond, which is also supported by At...
Source: Computational and Theoretical Chemistry - November 8, 2017 Category: Chemistry Source Type: research

A theoretical study on the hydrogen bond and stability of cytosine and thymine dimers
Publication date: Available online 8 November 2017 Source:Computational and Theoretical Chemistry Author(s): Magdalena Jawiczuk A theoretical examination of homo- and heterodimers of cytosine and thymine was performed at the B3LYP/6-311++G(2d,2p) theory level. The stability of hydrogen-bonded complexes along with their geometrical and energetical properties are presented. The new more stable thymine-thymine and cytosine-thymine dimers were found compared to the previous literature reports. Moreover, the proton affinity of O and N atoms and deprotonation enthalpies of cytosine and thymine are computed at the same level of ...
Source: Computational and Theoretical Chemistry - November 8, 2017 Category: Chemistry Source Type: research

Structural, electronic and magnetic properties of Pn+1 and FePn (n=1 –14) clusters
Publication date: 15 December 2017 Source:Computational and Theoretical Chemistry, Volume 1122 Author(s): S. Mahtout, N. Amatousse, F. Rabilloud Density functional theory calculations have been performed to study the geometrical structures, relative stabilities, electronic and magnetic properties of Pn+1 and FePn clusters in the range of n = 1–14 atoms. The search of the lowest-energy isomers has been performed by considering lots of structures for each clusters sizes. The putative geometries show that the frameworks of the lowest-energy isomers are three-dimensional structures and Fe atom tends to be located at an ...
Source: Computational and Theoretical Chemistry - November 8, 2017 Category: Chemistry Source Type: research

Thermodynamic Properties And Stability Of [B12hx(Cf3)12-X]2 − Anion Compex
In this study the thermodynamic properties of the dodecahydro-closo-dodecaborate anion B12H12 2− and its fluorinated derivatives, namely, B12Hx(CF3)12-x 2− (x = 9–12), have been calculated at the B3LYP-D3/6-311++G∗∗ level of theory. The calculated gas-phase heats of formation indicate the high thermodynamic stability of B12H12 2− anion complexes in which the hydrogen atoms are substituted by trifluoromethyl groups. Herewith, this stability increases with the increasing number of CF3 groups. According to Gibbs energy calculations, the formation of the B12Hx(CF3)12-x 2− anion compl...
Source: Computational and Theoretical Chemistry - November 7, 2017 Category: Chemistry Source Type: research

Theoretical Molecular Design of Hexasilabenzene Analogues Aiming for the Thermodynamic and Kinetic Stabilization
Publication date: Available online 7 November 2017 Source:Computational and Theoretical Chemistry Author(s): Taiji Nakamura, Takako Kudo A variety of synthesis strategy of hexasilabenzene (HSB) - the silicon analogue of benzene - is suggested on the basis of ab initio molecular orbital and DFT calculations. To overcome the difficulty of the isolation and to increase the thermodynamic and kinetic stabilities of HSB, various ideas are proposed by making efficient use of the substituent effects - theoretical molecular designing. For the purpose, the stability of HSB (BE-type) relative to the well-known valence isomers such a...
Source: Computational and Theoretical Chemistry - November 7, 2017 Category: Chemistry Source Type: research

First-principles study of NO molecules adsorption on Ag-doped CuO(111) surface
Publication date: Available online 7 November 2017 Source:Computational and Theoretical Chemistry Author(s): R.M. Hu, X.L. Zhou The surface structures, adsorption energies and electronic structures of NO molecules adsorbed on Ag-doped CuO(111) surface were investigated by using the density functional theory. The calculated results indicate that the Cu1-top site of the Ag-doped CuO (111) surface is the most favorable adsorption site for NO molecules. The adsorption energies of N atom as the adatom are greater than that of the O atom as the adatom. The high adsorption energy and short distance between NO and substrate indic...
Source: Computational and Theoretical Chemistry - November 7, 2017 Category: Chemistry Source Type: research

Tris(perfluoroalkyl)germylethynyl derivatives of biphenyl containing ferrocenyl donor group: structure, spectra, and photoinduced intramolecular electron transfer
Publication date: Available online 7 November 2017 Source:Computational and Theoretical Chemistry Author(s): E.P. Chuhmanov, N.L. Ermolaev, B.N. Plakhutin, S.K. Ignatov Ferrocenyl derivatives with perfluorinated organometallic fragments are prospective sensitizers for photovoltaic devices which can provide higher stability and resistance to oxidation in comparison with the known analogs. For the development of the photovoltaic devices based on such molecules, the estimates of probabilities of photoinduced electron transfer both inside the molecule and from the molecule to the internal semiconductor electrode are required....
Source: Computational and Theoretical Chemistry - November 7, 2017 Category: Chemistry Source Type: research

Optoelectronic and structural studies of a Ni(II) complex including bicyclic guanidine ligands: DFT calculations
Publication date: Available online 7 November 2017 Source:Computational and Theoretical Chemistry Author(s): H.A. Rahnamaye Aliabad, M. Chahkandi Structural and optoelectronic properties of NiCl2C14H26N6 complex (1) using DFT calculations by various exchange correlation potentials including PBE–Generalized Gradient Approximation (PBE–GGA) and hybrid density functional B3LYP are investigated. The complex belongs to monoclinic crystallographic system with P2(1)/n space group, Z=4. Selected 1 as monomeric unit (1−mon) through C−H···Cl hydrogen bonds (HBs) constructs a 2–D co...
Source: Computational and Theoretical Chemistry - November 7, 2017 Category: Chemistry Source Type: research

The nature of the noncovalent interactions between fullerene C60 and aromatic hydrocarbons
Publication date: Available online 4 November 2017 Source:Computational and Theoretical Chemistry Author(s): Yu Zhang, Weizhou Wang, Yi-Bo Wang To better understand the solubility of fullerenes in common aromatic organic solvents such as benzene, toluene, tetralin, 1,2,4-trimethylbenzene and 1-methylnaphthalene, the structures, energies and electronic properties of the complexes formed by fullerene C60 with benzene, toluene, tetralin, 1,2,4-trimethylbenzene and 1-methylnaphthalene, respectively, have been investigated by the density functional theory with long-range dispersion correction. It was found that the solubility ...
Source: Computational and Theoretical Chemistry - November 4, 2017 Category: Chemistry Source Type: research

Theoretical study on azafullerene structures with many NN connections, having an opening cavity
Publication date: 1 December 2017 Source:Computational and Theoretical Chemistry, Volume 1121 Author(s): A.-Reza Nekoei, Sanaz Haghgoo In continuing our investigations on the stability of nitrogen doped heterofullerenes with many NN connections, other isomers of two molecules C40N20 and C42N18 have been found out which possess a nitrogen chain. In these isomers the nitrogen chain is not in the middle of spherical fullerene, despite the previously introduced NB-isomers containing a nitrogen belt that NN continuum was in the middle of fullerene molecule. All quantum chemical calculations have been carried out using Gaussian...
Source: Computational and Theoretical Chemistry - November 4, 2017 Category: Chemistry Source Type: research

Weak binding mode of CH4 on rutile crystallites from density functional theory calculations
Publication date: 1 December 2017 Source:Computational and Theoretical Chemistry, Volume 1121 Author(s): Ali Abbaspour Tamijani In the recent years, the surfaces of oxides and fluorides have received considerable attention due to their suitability for emerging technologies such as fuel cells. Among these substances, well-known rutile TiO2, and rutile-like SnO2, MgF2 and ZnF2 are of particular interest owing to their utilization in a wide range of applications such as heterogeneous catalysis. In order to probe these materials for their catalytic activity, physisorption of small organic molecules, such as methane, on their ...
Source: Computational and Theoretical Chemistry - November 4, 2017 Category: Chemistry Source Type: research

Conformational and energetic properties of pyrrolidinyl PNA-DNA duplexes: A molecular dynamics simulation
Publication date: Available online 1 November 2017 Source:Computational and Theoretical Chemistry Author(s): Nattawee Poomsuk, Tawun Remsungnen, Tirayut Vilaivan, Andrew J. Hunt, Khatcharin Siriwong The binding capability of pyrrolidinyl peptide nucleic acids (PNAs) to DNA have been studied experimentally, also the high affinity and sequence specificity were reported. However, to date a detailed understanding of these properties is unclear due to a lack of crystallographic data. In this work, molecular dynamics (MD) simulations of pyrrolidinyl PNA with different stereochemistry, (2'R,4'R)- and (2'R,4'S)-prolyl-(1S,2S)-2-a...
Source: Computational and Theoretical Chemistry - November 2, 2017 Category: Chemistry Source Type: research

The low-lying doublet electronic excited states of ZrO2 −: A symmetry adapted cluster–configuration interaction (SAC-CI) study
Publication date: Available online 31 October 2017 Source:Computational and Theoretical Chemistry Author(s): Yung-Ching Chou The low-lying doublet excited states of ZrO2 − were studied using the SAC-CI method. The vertical excitation spectrum of ZrO2 − was calculated and compared with that of TiO2 −. Similar to that for TiO2 −, ZrO2 − also have a dipole-bound state. The ground electronic state (X2A1) and the excited states having bound characters (22A1, 12B1, and dipole-bound states) were optimized to C2v structures. The adiabatic electronic affinity of ZrO2 and the adiabatic excitation energ...
Source: Computational and Theoretical Chemistry - November 1, 2017 Category: Chemistry Source Type: research

Formaldehyde-mediated spectroscopic properties of heavy water from first principles simulation
Publication date: Available online 28 October 2017 Source:Computational and Theoretical Chemistry Author(s): Vivek Kumar Yadav Water shows incredible ability to form a rich variety of hydrogen bonded structure when encountered atmospheric solute. We have presented a first-principle Born-Oppenheimer molecular dynamics simulation for deuterated formaldehyde-water ( D 2 CO - D 2 O ) system with dispersion corrected density functional (BLYP-D3). We explicitly focus on the relaxation and spectroscopy associated with the CO mode of D2CO and its interaction with surrounding water molecules through deuterated-hydrogen bonding. Ou...
Source: Computational and Theoretical Chemistry - October 29, 2017 Category: Chemistry Source Type: research

Structural, electronic and magnetic properties of Pn+1 and FePn (n=1-14) clusters
Publication date: Available online 28 October 2017 Source:Computational and Theoretical Chemistry Author(s): S. Mahtout, N. Amatousse, F. Rabilloud Density functional theory calculations have been performed to study the geometrical structures, relative stabilities, electronic and magnetic properties of Pn+1 and FePn clusters in the range of n = 1 to 14 atoms. The search of the lowest-energy isomers has been performed by considering lots of structures for each clusters sizes. The putative geometries show that the frameworks of the lowest-energy isomers are three-dimensional structures and Fe atom tends to be located at an ...
Source: Computational and Theoretical Chemistry - October 28, 2017 Category: Chemistry Source Type: research

Free radicals interacting with Cu, Ag and Au clusters
Publication date: 15 November 2017 Source:Computational and Theoretical Chemistry, Volume 1120 Author(s): Miguel Reina, Ana Martínez We investigated free radical scavenger capacity of small neutral Cu, Ag and Au clusters (Cu, Ag and Au up to ten atoms, and Au20), using three molecules ( OH, OOH, OCH3) and two reaction mechanisms (Electron Transfer and Radical Adduct Formation). Principally this indicates that metal clusters are good free radical scavengers. They are good electron donors and the radical adduct formation reaction is thermodynamically feasible. Here, we show how Molecular Electrostatic Potential is ve...
Source: Computational and Theoretical Chemistry - October 27, 2017 Category: Chemistry Source Type: research

Ab initio study of electronic and optical properties of Fe doped anatase TiO2 (1  0 1) surface
Publication date: 15 November 2017 Source:Computational and Theoretical Chemistry, Volume 1120 Author(s): Dragan Toprek, Vasil Koteski, Jelena Belošević-Čavor, Valentin Ivanovski, Ana Umićević In this paper we investigated the effects of Fe -doping of the anatase TiO 2 (1 0 1) surface on the crystal structure, electronic and optical properties, and impurity formation energy by means of density functional theory (DFT). The calculations were performed by the SIESTA DFT code and were carried out by using Troullier-Martins pseudopotentials for the 12-electron valence configuration ( 3 s 2 3 p 6 3 d 2 4 s 2 ) ...
Source: Computational and Theoretical Chemistry - October 27, 2017 Category: Chemistry Source Type: research

Enhanced interaction of nickel clusters with pyridinic-N (B) doped graphene using DFT simulation
Publication date: 15 November 2017 Source:Computational and Theoretical Chemistry, Volume 1120 Author(s): Xuan Zhou, Wei Chu, Wenjing Sun, Yanan Zhou, Ying Xue The doping effects of nitrogen or boron atom on the stability of defective graphene supported Ni n (n =1–6) clusters were explored using density functional theory (DFT) approaches, while the configurations of pyridinic-B and pyridinic-N doped defective graphene (PBG, PNG) were constructed. The binding energies of Ni n clusters on doped defective graphene are both higher than that of Ni n on pristine graphene (PG). It is indicated that the interaction between ...
Source: Computational and Theoretical Chemistry - October 27, 2017 Category: Chemistry Source Type: research

A DFT Investigation of Substituent Effects on Carbon Dioxide Fixation: by a Low-Coordinate Cobalt (I) Complex
Publication date: Available online 24 October 2017 Source:Computational and Theoretical Chemistry Author(s): Bruce M. Prince CO2 fixation barriers are central to identifying catalysts for the reaction of carbon dioxide and C-H bonds to form carboxylic acids. The Co(I) complexes (Xdab)Co(Me) (dab = 1,4-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-butadiene where X = H, Me, OH, and NO2) mediate the formation of acetic acid from carbon dioxide (CO2) and methane. The stationary point geometries reveal agostic interactions involving the methyl groups of the acetate intermediates. The model catalysts are selective for carboxylic ac...
Source: Computational and Theoretical Chemistry - October 25, 2017 Category: Chemistry Source Type: research

Substitutional doping of zirconium-, molybdenum-, ruthenium-, and palladium: An effective method to improve nonlinear optical and electronic property of C20 Fullerene
Publication date: Available online 25 October 2017 Source:Computational and Theoretical Chemistry Author(s): Ali Shokuhi Rad, Khurshid Ayub Density functional theory calculation are performed for electronic and nonlinear optical properties of C20 fullerene substitutionally doped with 2nd row transition metal (Zirconium (Zr), molybdenum (Mo), ruthenium (Ru), and palladium (Pd)). The results revealed that the charge distribution of C20 fullerene changes remarkably when a carbon atom of C20 is replaced with transition metal element. We found that Zr and Mo atoms can slightly narrow the wide HOMO-LUMO gap of the pure C20 full...
Source: Computational and Theoretical Chemistry - October 25, 2017 Category: Chemistry Source Type: research

Computer-aided Design of Molecularly Imprinted Polymers for Recognition of Atrazine
Publication date: Available online 21 October 2017 Source:Computational and Theoretical Chemistry Author(s): Yi Han, Lili Gu, Mengxiao Zhang, Zhijun Li, Wanming Yang, Xiaoning Tang, Gang Xie Density functional theory (DFT) method was performed to preliminarily select monomers and solvents for the preparation of atrazine molecularly imprinted polymers (MIPs). The probabilities of forming non-covalently bonded complexation between the template and five commonly used monomers were evaluated by electronic interaction energy. These monomers involved acrylic acid, methacrylic acid, 2-(trifluoromethyl) acrylic acid, acrylamide a...
Source: Computational and Theoretical Chemistry - October 22, 2017 Category: Chemistry Source Type: research

Conformational disorder in polysilylenes studied theoretically on tetramers
Publication date: Available online 21 October 2017 Source:Computational and Theoretical Chemistry Author(s): Barbora Hanulikova, Ivo Kuritka DFT calculations with B3LYP, M06 and ωB97X-D functionals with 6-31G∗ basis set are used for a study of non-bonding intramolecular interactions in tetra[methyl(phenyl)silylene] (MPSi4), tetra[(dimethyl)silylene], tetra(silylene) (Si4) and further in molecules of tetra[cyclohexyl(methyl)silylene] and carbon chain analogue of MPSi4. A tetramer can serve as a model for conformational defect – a kink that is worth to understand especially in case of polysilylenes. The k...
Source: Computational and Theoretical Chemistry - October 22, 2017 Category: Chemistry Source Type: research

Theoretical study of high performance hydrocarbon-based ion-exchange membranes
Publication date: Available online 20 October 2017 Source:Computational and Theoretical Chemistry Author(s): Akinori Fukushima, Hironori Sakai, Takashi Tokumasu To obtain a basic insight for developing hydrocarbon based polymer membranes that have high proton conductivity, we designed new molecules by introducing the sulfonyl group (SO2) into various positions of benzene sulfonic acid and analyze their deprotonation reaction. We evaluated the activation and stabilization energies of deprotonation reactions of these model molecules with three water molecules. The energies were highly dependent on the positions of the sulfo...
Source: Computational and Theoretical Chemistry - October 21, 2017 Category: Chemistry Source Type: research

Theoretical study on azafullerene structures with many N –N connections, having an opening cavity
Publication date: Available online 21 October 2017 Source:Computational and Theoretical Chemistry Author(s): A.-Reza Nekoei, Sanaz Haghgoo In continuing our investigations on the stability of nitrogen doped heterofullerenes with many N–N connections, other isomers of two molecules C40N20 and C42N18 have been found out which possess a nitrogen chain. In these isomers the nitrogen chain is not in the middle of spherical fullerene, despite the previously introduced NB-isomers containing a nitrogen belt that N–N continuum was in the middle of fullerene molecule. All quantum chemical calculations have been carried ...
Source: Computational and Theoretical Chemistry - October 21, 2017 Category: Chemistry Source Type: research

Quantum-chemical studies on the favored and rare isomers of isocytosine
Publication date: Available online 19 October 2017 Source:Computational and Theoretical Chemistry Author(s): Ewa D. Raczyńska Quantum-chemical calculations have been performed for twenty-one favored and rare isomers of neutral isocytosine in two extreme media, in the gas phase {B3LYP/6-311+G(d,p)} and in aqueous solution {PCM(water)//B3LYP/6-311+G(d,p)}. In aqueous solution, the most aromatic hydroxy-amino form, favored in the gas phase, becomes a rare form, and less delocalized amino-oxo forms predominate. Monoprotonation of the favored isomers leads also to two different forms, the N1-protonated hydroxy-amino cation in...
Source: Computational and Theoretical Chemistry - October 20, 2017 Category: Chemistry Source Type: research

Ab initio study of cationic water cluster (H2O)9+ via particle swarm optimization algorithm
Publication date: 15 November 2017 Source:Computational and Theoretical Chemistry, Volume 1120 Author(s): Lan-Ting Shi, Mei Tang, Xiang-Rong Chen, Cui-E Hu, Yan Cheng The 16 lowest energy isomers of cationic water cluster (H2O)9 + have been comprehensively searched by the particle swarm optimization algorithm combined with quantum chemistry calculations. Geometric optimization and vibration analysis of the interesting isomers were made in the MP2/aug-cc-pVDZ level. Our results show that cage structure is the most stable at low temperatures. The relative Gibbs free energy below 400K was calculated, which indicates that the...
Source: Computational and Theoretical Chemistry - October 20, 2017 Category: Chemistry Source Type: research