Li Xiao-Hong

Computational study of imidazole derivative as high energetic materials

Density functional theory (DFT) calculations were performed for a series of imidazole derivatives. B3LYP and B3P86 functionals with 6-31G** basis set were used. Heats of formation (HOFs) were predicted through designed isodesmic reactions. Calculated results show that the HOFs relate to the number and the position of nitro groups. The HOFs increase with the augment of the number of the NO(2) group for the direct imidazole derivatives and decrease with the augment of the number of the NO(2) group for 1-picrylimidazole derivatives. Thermal stabilities were evaluated via bond dissociation energies (BDEs). The result shows that the increase of nitro group number on imidazole ring reduces the stability of the molecule. Further, the correlation was developed between impact sensitivity h(50) and the ratio (BDE/E) of the weakest bond BDE to the total energy E. The detonation performance data were also calculated.

Density Functional Theory Study of Several Nitrotriazole Derivatives

Quantum chemical calculations at B3LYP/6-31G* and B3P86/6-31G* levels are used to predict the bond dissociation energies (BDEs) of seven nitrotriazole derivatives. It is noted that the BDEs of the initial scission step are between 44 and 70 kcal/mol, which are larger than those of piperidine and diazocine compounds and polynitro benzoate molecules. In addition, substituent groups greatly affect the bond dissociation energies of the title compounds. The heats of formation (HOFs) for seven energetic materials are also calculated via designed isodesmic reactions. From computational results it is noted that substituent groups strongly affect the HOFs. The research demonstrated that the HOF of the compound substituted by a five-membered ring is larger than those substituted by a six-membered ring for 1,2,4-triazole. The detonation performance data of the title compounds are also calculated according to the HOFs calculated by B3LYP/6-31G* level.

Theoretical investigation on the non-linear optical properties, vibrational spectroscopy and frontier molecular orbital of (E)-2-cyano-3-(3-hydroxyphenyl)acrylamide molecule.

The vibrational frequencies of (E)-2-cyano-3-(3-hydroxyphenyl)acrylamide (HB-CA) in the ground state have been calculated using density functional method (B3LYP) with B3LYP/6-311++G(d,p) basis set. The analysis of natural bond orbital was also performed. The IR spectra were obtained and interpreted by means of potential energies distributions (PEDs) using MOLVIB program. In addition, the results show that there exists C-H⋯O hydrogen bond in the title compound, which is confirmed by the natural bond orbital analysis. The predicted NLO properties show that the title compound is a good candidate as nonlinear optical material. The analysis of frontier molecular orbitals shows that HB-CA has high excitation energies, good stability and high chemical hardness. The analysis of MEP map shows the negative and the positive potential sites.

Computational investigation of the heat of formation, detonation properties of furazan-based energetic materials

The heats of formation (HOFs) for a series of furazan-based energetic materials were calculated by density functional theory. The isodesmic reaction method was employed to estimate the HOFs. The result shows that the introductions of azo and azoxy groups can increase the HOF, but the introduction of azo group can increase the more HOF, when compared with azoxy group. The detonation velocities and detonation pressures of the furazan-based energetic materials are further evaluated at B3LYP/6-31G* level. Dioxoazotetrafurazan and azoxytetrafurazan may be regarded as the potential candidates of high-energy density materials because of good detonation performance. In addition, there are good linear 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. These results provide basic information for the molecular design of novel high-energy density materials.

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

AbstractDensity 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. Graphical AbstractThe IR spectrum, heat of formation and thermodynamic properties of a new polynitro cage compound were calculated by theoretical method. The results show that the obtained crystal structure belongs to P21/C space group. There exists a good linear relationship between the WBIs of N-NO2 bonds and the charges –QNO2.

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

AbstractDensity 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. Graphical AbstractDensities, detonation velocities and pressures for a series of 1,2,4-triazole derivatives, as well as their thermal stabilities, were investigated to look for high energy density compounds (HEDCs). Heats of formation (HOFs) were also calculated via designed isodesmic reactions. 5,5′-Dinitro-3,3′-bi-1,2,4-triazole, 3-nitro-1-picryl-1,2,4-triazole and 4-(2,4-dinitrobenzyl)-3,5-dinitro-1,2,4-triazole satisfy the quantitative standard of HEDC.

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

AbstractBased on the full optimized molecular geometric structures at B3LYP/6-311++G**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. Graphical AbstractComputational results show that ditetrazoles combined with -NF2 group except B-NF2 have higher densities, larger D and P. F-NF2 may be regarded as the potential candidate of HEDMs because of the largest detonation velocity and pressure among these derivatives.

Theoretical investigation of a series of bis(1H-tetrazol-5-yl)furazan and bis(1H-tetrazol) derivatives as high-energy-density materials

ABSTRACT Using density functional theory (DFT), a series of bis(1H-tetrazol-5-yl)furazan and bis(1H-tetrazol) derivatives with different linkages and substituents are investigated theoretically as potential high-energy-density materials (HEDMs). The heat of formation (HOF), detonation properties, natural bond orbital (NBO) and thermal stabilities are calculated and reported. The introduction of a furazan ring, an –N=N– bridge group and an –N3 substituent is beneficial to increase the HOF of the title compounds. NBO analysis shows that there are electronic delocalisation effects among the bridge groups, furazan and tetrazole rings, and substituted groups. The conjugation effects and electronic transitions are influenced by the different linkages and substituents. The estimated detonation velocities and pressures indicate that the –ONO2 and –NO2 groups and the –N=N– linkage play important roles in enhancing the detonation properties. The bond dissociation energy (BDE) calculations reveal that the –NO2 group is the substituent group which causes the least thermal stability. The bond between the substituent group and the tetrazole ring is the weakest bond in the title molecules. Considering the detonation performance and the thermal stability, 17 compounds may be promising candidates for HEDMs with good performance. Eight of them (A3, A4, C3, C4, D3, F3, G1 and G3) have better detonation properties than HMX.

Theoretical studies on energetic materials bearing pentaflurosulphyl (SF5) groups

AbstractHeats 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. Graphical AbstractSF5 group is an important energetic group. Considering the importance of the SF5 group, a series of energetic materials containing SF5 group were investigated to discuss the HOF, BDE and detonation properties in order to search for compounds with better performance.

Structural properties and S—S dissociation energies in a series of disulfide compounds: a theoretical study

The equilibrium structures and bond dissociation energies (BDEs) of 13 disulfide compounds have been investigated by several hybrid density functional theory (B3P86, B3LYP, and B3PW91) methods. From our calculation, it has been found that all the values of the bond length fall into a narrow range between 2.06 and 2.15 Å except those of the bond length of the halogen-substituted compounds and C6H5S–SC6H5 molecule. The research about BDE shows that the B3P86 method can provide better results than the B3LYP and B3PW91 methods. In addition, it has been found that the uses of diffuse function and basis set superposition error calculation reveal improved results. Large deviations between the computational results and experimental values for FS–SF and ClS–SCl exist as a result of radical relaxation effect.