Xuedong Gong

Ab initio studies on four alkyl nitric esters

Abstract Ab initio calculations at various levels have been performed to investigate the geometries and electronic structures of methyl, ethyl, propyl and butyl nitrates. The calculated results at various levels are compared with the available experimental results and with each other. The geometrical parameters of methyl and ethyl nitrates calculated by MP2/6-311G ∗ are in very good agreement with the experimental gas-phase results.

Ab initio studies on the conformations, thermodynamic properties and rotational isomerization of diphenylamine (DPA)

Abstract Molecular orbital ab initio calculations were performed at the MP2/6-31G* and HF/6-31G* levels to investigate the conformations and properties of diphenylamine (DPA). According to the MP2/6-31G* results, DPA has two rotational optical isomers which differ only in the direction of rotation of the phenyl rings. Two rings in each conformer are essentially planar. One is distorted around the C–N bond by 9.6° and another by 46.8°, and the angle between them is 52.4°. Inclusion of electron correlation shrinks the C–N bonds and the ∠C–N–C angle, stretches the C–C bonds and increases the H⋯H non-bonded distance between the two rings. The standard thermodynamic properties, enthalpy( H 0 ), entropy( S 0 ) and heat capacity( C p 0 ), as well as the kinetic rate constant for rotational conversion between the isomers of DPA at various temperatures were also derived using the scaled HF/6-31G* IR frequencies. The low internal rotational barrier (7.76xa0kJxa0mol −1 ) and high rate coefficient (about 10 14 xa0lxa0mol −1 xa0s −1 ) imply that rotational conversion between the two isomers are very easy.

QSARs for congener-specific toxicity of polyhalogenated dibenzo-p-dioxins with DFT and WHIM theory.

Polyhalogenated dibenzo-p-dioxins (PHDDs) have become the most notorious pollutants in the environment. However, the origin of their congener-specific toxicity is not well understood. For explaining the difference in toxicity between PHDDs as well as their potencies of aryl hydrocarbon hydroxylase (AHH) and 7-ethoxyresorufin O-deethylase (EROD) induction, quantitative structure-activity relationships (QSARs) were constructed through the combined application of DFT (density functional theory) and WHIM (weighted holistic invariant molecular) theory. Results from the QSAR analyses suggest that dispersion interaction along the lateral sites of PHDDs should interpret the vast majority of variance of binding affinities as well as the consequent toxicity. Although electrostatic interaction is comparatively less influential, it should not be negligible. Long-range dispersion interaction is also described in QSARs with minute influence. Quadrupole moment tensor perpendicular to the ring plane, i.e., Q(zz) and its implicated electrostatic interaction plays an important role in the contribution to induction potencies.

Ab initio study of solvent effects on the structure and vibrational frequencies of methyl nitrate

Abstract Ab initio calculations have been performed on methyl nitrate in gas phase employing the self-consistent field (SCF) theory at HF/6-31G ** level and in different solvents, i.e. water, acetonitrile, ethyl alcohol and dichloroethane, utilizing the self-consistent reaction field (SCRF) theory. Reasonable agreement has been found between the computed and the experimental results in gas phase. The effects of solvents on the geometry, electronic structure and IR frequencies are discussed. Various solvents under consideration are found to have similar effects on above properties.

Substituent Effect on Infrared Spectra and Thermodynamic Properties of Polynitroamino Substituted Cyclopentane and Cyclohexane

Density functional theory method was employed to study the effect of the nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct polycyclic or caged nitramines. Based on the optimized molecular structures of two groups of monocyclic nitramines at the B3LYP/6-31G** level, the infrared (IR) spectra were obtained and assigned by harmonic vibrational analysis. The calculated results agree reasonably with the available experimental data. According to the principles of statistic thermodynamics, thermodynamic properties were derived from the IR spectra, which were linearly correlated with the number of nitroamino groups as well as the temperature. The contributions of nitroamino groups to thermodynamic properties are in accord with the group additivity.