Xian-Zhou Zhang

Theoretical studies of 1,2,4,5-tetrazine-based energetic nitrogen-rich compounds

Density functional theory calculations were performed to find the relationships between the structures and performance of a series of 1,2,4,5-tetrazine-based energetic derivatives. The isodesmic reaction method was employed to estimate the heats of formation (HOFs). The result shows that the azo or azoxy group is one of the most energetic functional groups known and its substitution can drastically increase HOFs of a molecule. The detonation properties were also evaluated by the Kamlet–Jacobs equations based on the theoretical densities and HOFs. Results show that NO2 group is an effective substituent for enhancing the detonation performance. There exist better correlations between OB and detonation velocities and OB and detonation pressures. The energy gaps between the HOMO and LUMO of the studied compounds are also investigated, and from the data we estimated the relative thermal stability ordering of the title compounds.

Theoretical Study of the CCl Bond Dissociation Enthalpy and Electronic Structure of Substituted Chlorobenzene Compounds

Quantum chemical calculations were used to estimate the bond dissociation energies (BDEs) for 13 substituted chlorobenzene compounds. These compounds were studied by the hybrid density functional theory (B3LYP, B3PW91, B3P86) methods together with 631G** and 6311G** basis sets. The results show that B3P86/6311G** method is the best method to compute the reliable BDEs for substituted chlorobenzene compounds which contain the CCl bond. It is found that the CCl BDE depends strongly on the computational method and the basis sets used. Substituent effect on the CCl BDE of substituted chlorobenzene compounds is further discussed. It is noted that the effects of substitution on the CCl BDE of substituted chlorobenzene compounds are very insignificant. The energy gaps between the HOMO and LUMO of studied compounds are also investigated and from this data we estimate the relative thermal stability ordering of substituted chlorobenzene compounds.

PCM Study of Bond Dissociation Energies of the S–NO Bond: A DFT Study

Quantum chemical calculations are used to estimate the equilibrium S–NO bond dissociation energies (BDEs) for seven S-nitro-N-acetyl-d,l-penicillamine dipeptides (SNAP-two peptides) in acetonitrile solution. These compounds were studied by employing the hybrid density functional theory (B3LYP, B3P86 and B3PW91) methods together with the 6-31G** basis set. The obtained results are compared with available experimental results. It is demonstrated that B3PW91 method is the best method to compute the bond dissociation energies of SNAP-two peptides. The substituent and solvent effects of the S–NO BDEs are further analyzed. The results show that S–NO BDE increases with the increment of isoelectric points of substituted groups. In addition, the S–NO BDE decreases due to the inclusion of solvent effects. Furthermore, SNAP-two peptides and the other NO-donors are compared.

NNO2 bond dissociation energies in acetonitrile: An assessment of contemporary computational methods

The assessment of the N-NO2 bond dissociation energies (BDEs) was performed by various calculating methods (B3LYP, B3PW91, B3P86, B1LYP, BMK, MPWB1K, PBE0, CBS-4M and M06-2X) at 6-311+G(2d,p) basis set. Compared with the experimental BDEs, the results show that BMK and B3P86 methods reproduce the experimental values well. The mean absolute deviations from the experimental values obtained by BMK and B3P86 methods were 0.5 and 1.5 kcal/mol, respectively. B3LYP, B3PW91, B1LYP, MPWB1K and PBE0 methods underestimated the homolytic N-NO2 BDEs. B3LYP, B3PW91, B1LYP, M06-2X, CBS-4M methods failed to provide an accurate description of N-NO2 BDEs for N-Nitrosulfonamide compounds and showed larger mean absolute deviations and maximum deviations. Further, substituent effect based on BMK/6-311+G(2d,p) method was analysis. Natural bond orbital analysis shows that there exist good linear correlations between E((2)) of lpN1→BD*(O1-N2) and Hammett constants and a better correlation between the BDEs and the second order stabilization energy E((2)) of lpN1→BD*(O1-N2).

PCM Study of Some N-Nitroso-N′,N′-dimethylphenylurea Biological Molecules: A Natural Bond Orbital Analysis

The density functional B3LYP method with the 6-31++G(d,p) basis set was used to investigate several N-nitroso-N′,N′-dimethylphenylurea biological molecules in MeCN solution. Geometries obtained from DFT calculation were used to perform natural bond orbital (NBO) analysis. The p characters of two nitrogen natural hybrid orbital (NHO),

Natural bond orbital analysis of some para-substituted N-nitrosoacetanilide biological molecules

\sigma_{\mathrm{N}_{3}\mbox{\scriptsize{--}}\mathrm{N}_{2}}

Theoretical studies on a series of 1,2,3-triazoles derivatives as potential high energy density compounds

bond orbitals, increase with increasing σp values of the substituents on the benzene, which results in a lengthening of the N3–N2 bond. The p character of the oxygen NHO

Computational DFT studies on a series of toluene derivatives as potential high energy density compounds

\sigma_{\mathrm{O}_{1}\mbox{\scriptsize{--}}\mathrm{N}_{2}}

Molecular structure and vibrational spectra of phenobaraitone by density functional theory and ab initio hartree-Fock calculations

bond orbital decreases with increasing σp values of the substituents on the benzene, which results in a shortening of the N2=O1 bond. It is also noted that decreased occupancy of the localized

Theoretical investigation of some O-nitrosyl carboxylate biologic molecules — A natural bond orbital study

\sigma_{\mathrm{N}_{3}\mbox{\scriptsize{--}}\mathrm{N}_{2}}