• Li Xiao-Hong

      Articles written in Journal of Chemical Sciences

    • The solvent and substituent effects on bond dissociation energies of NO-donor molecules containing the N-NO bond

      Li Xiao-Hong Li Wei-Bin Zhang Xian-Zhou

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      Quantum chemical calculations are used to estimate the equilibrium N-NO bond dissociation energies (BDEs) for 15 NO-donor molecules in acetonitrile. These compounds are studied by employing the hybrid density functional theory (B3LYP, B3PW91, B3P86) methods together with 6-31G∗∗ basis set. The basis set superposition error (BSSE) and zero-point vibrational energy (ZPVE) are considered. The results are compared with the available experimental results. It is demonstrated that B3LYP/6-31G$^{\ast\ast}$ is accurate to compute the reliable BDEs for the NO-donor molecules. The solvent effects on the N-NO BDEs are analysed and the result shows that the N-NO BDEs in a vacuum computed by B3P86/6-31G∗∗ method are the closest to the computed values in acetontrile and the average solvent effect is 0.78 kcal/mol. Subsequently, the substituent effects on the N-NO BDEs are further analysed and it is found that electron donating group stabilizes the radical and as a result BDE decreases; whereas electron withdrawing group stabilizes the ground state of the molecule and thus increases the BDE.

    • Theoretical studies on a series of 1,2,4-triazoles derivatives as potential high energy density compounds

      Zhang Rui-Zhou Li Xiao-Hong Zhang Xian-Zhou

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      Density functional theory calculations at B3LYP/6-31G∗∗ and B3P86/6-31G∗∗ levels were performed to predict the densities (𝜌), detonation velocities (D), pressures (P) and the thermal stabilities for a series of 1,2,4-triazole derivatives for looking high energy density compounds (HEDCs). The heats of formation (HOFs) are also calculated via designed isodesmic reactions. The calculations on the bond dissociation energies (BDEs) indicate that the position of the subsitutent group has great effect on the BDE and the BDEs of the initial scission step are between 31 and 65 kcal/mol. In addition, the condensed phase heats of formation are also calculated for the title compounds. These results would provide basic information for further studies of HEDCs.

    • Theoretical investigation on crystal structure, detonation performance and thermal stability of a high density cage hexanitrohexaazaisowurtzitane derivative

      Li Xiao-Hong Cui Hong-Ling Li Li-Ben Zhang Xian-Zhou

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      Density functional theory calculations were performed to study the new polynitro cage compound with the similar framework of HNIW. IR spectrum, heat of formation and thermodynamic properties were predicted. The bond dissociation energies and bond orders for the weakest bonds were analysed to investigate the thermal stability of the title compound. The detonation and pressure were evaluated by using the Kamlet-Jacobs equations based on the theoretical density and condensed HOFs. In addition, the results show that there exists an essentially linear relationship between the WBIs of N-NO2 bonds and the charges -QNO2 on the nitro groups. The crystal structure obtained by molecular mechanics belongs to P21/C space group, with lattice parameters Z = 4, a = 12.3421 Å, b = 24.6849 Å, c = 20.4912 Å, 𝜌 = 1.896 g cm-3. The designed compound has high thermal stability and good detonation properties and is a promising high energy density compound.

    • Theoretical studies on energetic materials bearing pentaflurosulphyl (SF5) groups

      Li Xiao-Hong Cui Hong-Ling Ju Wei-Wei Li Tong-Wei Zhang Rui-Zhou Yong Yong-Liang

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      Heats of formation (HOF) for a series of energetic materials containing SF5 group were studied by density functional theory. Results show that HOFs increase with the augmention of field effects of substituted groups. Addition of furazan or furoxan ring increases HOF of the energetic materials. All the SF5-containing compounds have densities which are ∼0.19 g/cm3 higher than those containing -NH2 group. S-F bond is the trigger bond for the thermolysis process in the title compounds and bond dissociation energies of the weakest bonds range from 351.1 to 388.3 kJ/mol. Detonation velocities (D) and pressures (P) are evaluated by Kamlet-Jacobs equations with the calculated densities and HOFs. Results show that increasing the amount of furazan rings results in a larger D and P. Considering the detonation performance and thermal stability, eight compounds may be considered as potential candidates for high-energy density materials.

    • Computational studies on energetic properties of nitrogen-rich energetic materials with ditetrazoles

      Li Xiao-Hong Zhang Rui-Zhou

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      Based on the full optimized molecular geometric structures at B3LYP/6-311++G$^{\ast\ast}level, the densities (𝜌), heats of formation (HOFs), detonation velocities (D) and pressures (P) for a series of ditetrazoles derivatives, were investigated to look for high energy density materials (HEDMs). The results show that the influence of different substituted groups on HOFs has the order of -N3>-CN>-NH2>-NO2>-NF2>-ONO2>-H>-CH3>-CF3. The introduction of -CF3 groups is more favourable for increasing the density and the introduction of -CH3 groups is not favourable for increasing the density. In addition, all the series combined with -NF2 group except B-NF2 all have higher densities, larger D and P. F-NF2 may be regarded as the potential candidates of HEDMs because of the largest detonation velocity and pressure among these derivatives.The energy gaps between the HOMO and LUMO of the studied compounds are also investigated.

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