Journal of Physical and Theoretical Chemistry
Volume:13 Issue: 2, Summer 2016

A novel Pyridine-2,6-dicarboxylic acid mixed ligands complex of formula [Co(NO3)2].6H2O has been obtained by the reaction of Pyridine-2,6-dicarboxylic acid with cobalt nitrate and 1,10-phenanthroline on heating in water. The structures of [Co(pydc)(Phen)(H2O)](pydcH2).4H2O receptors, and their complexes were optimized using DFT method at the B3LYP/3-21G** level. The highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO) energies have been derived at the same level of theory. All the calculations were performed using the GAUSSIAN 03 program. The optimized geometries and frequencies of the stationary point are calculated at the B3LYPlevel of theory. The large HOMO-LUMO energy gap, both in neutral and anionic form, further provide evidence of their stability.Complex structure of the protein withamino acid groups is shown. All chemicals purchased were of reagent grade or better and were used without further purification.

In present study, the density functional theory (DFT-B3LYP) method with SVP basis set was used for optimizing and studying the electronic structural properties of cis and trans isomers of bis-(5-nitro-2H-tetrazolato-N2) tetraammine cobalt (III) perchlorate (BNCP) as powerful explosives at 298.15 K temperature and 1 atmosphere pressure. And also, Natural Bond Orbital (NBO) population analysis and the molecular electrostatic potential (MEP) surface of the structures were studied by mentioned level of theory. The effect of ligands sites attached to the transition metal (cobalt) at the BNCP isomers was studied on the HOMO-LUMO energies, the electronic chemical potential, the absolute hardness and electrophilicity index. The geometry optimization of the structures shows the octahedral environment around cobalt. The tetrazole nitrogen atoms have large negative charge. The three-dimensional electrostatic potential maps of the isomers show that the negative charge is located on the nitro and perchlorate groups. The NBO analysis shows that the Co-ligand bonds in the near of perchlorate ion are formed from short, strong and sigma bonds.

To investigate non-bonded interaction of Phenanthrene and BN nanostructure, geometric structure of Phenanthrene and B12N12 nano-ring with B3LYP method and 6-31g* basis set are optimized by using ab initio gaussian quantum chemical package. The main purpose of this study was to evaluate changes of electronic properties of aromatic compound in presences Nano ring field. Therefore reactivity and stability of Phenanthrene alone and in the presence of B12N12 nanoring checked by density functional theory. To studying the non-bonded interaction energies between Phenanthrene and B12N12 nano-ring at the first time we determined the best orientation and distance of optimized structure and then NBO and NMR calculations have been done that explains reduce the reactivity, increase stability of Phenanthrene. So that shows HOMO orbitals matches the Phenanthrene and LUMO orbitals matches the Nano ring. Then charge transfer of Phenanthrene and Phenanthrene -B12N12 studies that represents the flow of electrons from the Nano ring to the Phenanthrene.

The N-(2-benzoyl-phenyl) oxalyl derivatives are important models for studying of three-centered intramolecular hydrogen bonding in organic molecules. The quantum theoretical calculations for two crystal structures of N-(2-benzoyl-phenyl) oxalyl (compounds I and II) were performed by Density Functional Theory (B3LYP method and 6-311+G* basis set). From the optimized structures, geometric parameters were obtained and experimental measurements were compared with the calculated data. The NMR parameters such as chemical shift isotropic (CSI) and chemical shift anisotropic (CSA), natural charge (NBO), thermodynamic parameters such as relative energy (ΔE), standard enthalpies (ΔH), entropies (ΔS), Gibbs free energy (ΔG) and constant volume molar heat capacity (Cv), frontier molecular orbitals (FMOs), total density of states (DOS), molecular electrostatic potential (MEP) of the two structures were investigated by theoretical calculations. Molecular properties such as Ionisation Potential (I), Electron affinity (A), chemical hardness (η), electronic chemical potential (μ) andelectrophilicity (ω) obtained and three-centered intramolecular hydrogen bonding were investigated by NBO analysis.

E-2-Arylmethylen-1- tetralones and E-3-phenylme thylene chromanone-4-ones and their derivatives closely related to flavonoids belong to the plant secondary metabolites most investigated recently.The class of flavonoids is an enormous class of plant secondary metabolites having so different pharmacological effects as inhibition of nitric oxide synthasecancer preventive effect or potential impact on the etiology of certain vascular disease.Numerous biological activity have been attributed to the tetralones mentioned. In this study B3P86/6-31++G* was used to compute and map the molecular surface electrostatic potentials of a group of tetralones and chromanones to identify common features related to their lipophilicity. Several statistical properties including potentials extrema (Vs,min, Vs,max), the average of positive electrostatic potential on the surface (Vst), the average of V(r), over the surface (Vs) and the variance of V(r) over the surface (62-) and system lipophilicity were computed. Statistically, the most significant correlation is a three parameter equation with correlation coefficient, R value of 0.881 and R2adj=0.743. The obtained models allowed us to reveal lipophilicity activity of tetralones.

Electronic effects were investigated on the singlet–triplet energy gaps of divalent unsaturated seven- membered ring R2C6H6M (M=C, Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) at B3LYP/6-311++G** level. All the triplet states of R2C6H6C were more stable than the related the singlet states while all the singlet states of R2C6H6M (M= Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) were more stable than the related triplet states. The ∠C2-M1-C7 angle of all the triplet states of R2C6H6M is larger than their singlet states. Calculated dihedral angles indicated a nonplanar structure for both singlet and triplet states of R2C6H6M. The NBO charge at heteroatom center (M) of R2C6H6M (M=C, Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) for both singlet and triplet states were generally increased when the bulky substituent (R = t-Bu) were placed at 2 and 7 (α–position) of seven membered ring. The chemical hardness (η) value for triplet states of R2C6H6M (M=C, Si, Ge, Sn R= –H, -CH3, i-Pr , t-Bu) were larger than the corresponding singlet states. A linear correlation was found between the LUMO–HOMO energy gaps of the singlet species, and their corresponding ΔGt–s..

Influence of Aluminum, Gallium, Indium- Doping on the Boron-Nitride Nanotubes (BNNTs) investigated with density functional theory (DFT) and Hartreefock (HF) methods. For this purpose, the chemical shift of difference atomic nucleus was studied using the gauge included atomic orbital (GIAO) approch. In the following, structural parameter values, electrostatic potential, thermodynamic parameters, chemical hardness, chemical potentials, the Maximum amount of electronic charge transfer, electrophilicity and electronegativity for the tittle structure was studied in different states. Our results show that doping of Aluminum, Gallium, Indium atoms to the nanotube surface leading to changesin theIsotropic Chmical Shift, Anisotropic Chemical Shift, also chemical and the rmodynamic parameters will follow the regular process changes.

We have theoretically studied the electron paramagnetic resonance (EPR) properties of paramagnetic O2 − , N2 − and Cl2 − centers in the KCl and NaCl crystals. The calculations have been performed by the density functional theory (DFT) method with the B3LYP correlation functional at 6-31 G(d) level. The attention has been focused on the calculation of the variations of the EPR parameters such as the isotropic g- and A-values. These parameters were satisfactorily calculated for all three species with the orientation of the trapped radicals along all three axes of the crystals for the first time. Namely the molecular axis of the paramagnetic anions was oriented along the x, y and z directions of the crystallographic axes, which can experimentally never be done, and the variations of the EPR parameters were theoretically determined and analyzed as if the each of them is a tensor. And then their principal values and direction cosines were obtained. It was concluded that the anisotropy of the g- and A-values increases while the bond length of the molecular anion radical increases.

Quantitative Structure-Activity Relationship (QSAR) models are useful in understanding how chemical structure relates to the biological activity and the toxicity of natural and synthetic chemicals. In the present investigation the applicability of various topological indices and physicochemical descriptor are tested for the QSAR study on benzene derivatives. The topological indices used for the QSAR analysis were Szeged (Sz), Randic (1X) (the first order molecular connectivity), Balaban (J), HyperWiener (HW), Wiener Polarity (WP) and Harary (H) indices. The physicochemical descriptor is also used in the study (n-octanol/water partition coefficient (logP). For obtaining appropriate QSTR model we have used multiple linear regression (MLR) techniques and followed back ward regression analysis. The results have shown that best models are obtained by multi parametric analysis. The toxicities of 45 benzene derivatives are well predicted by a tri parametric model consisting of HyperWiener (HW), Wiener Polarity (WP) and partition coefficient (logP) as the correlating parameters. The predictive ability of the model is discussed on the basis of predictive correlation coefficient.