Longyu Liao

5,6-Di(2-fluoro-2,2-dinitroethoxy)furazano[3,4- b ]pyrazine: a high performance melt-cast energetic material and its polycrystalline properties

5,6-Di(2-fluoro-2,2-dinitroethoxy)furazano[3,4-b]pyrazine was synthesized in a three-step process starting from 3,4-diaminofurazan (DAF) including a significant nucleophilic substitution reaction under the catalytic effect of trisodium phosphate dodecahydrate. Characterization of this molecule indicates that it possesses a higher crystal density than that of 2,4,6-trinitrotoluene (TNT) at ambient temperature with acceptable melting-point and energetic properties approaching those of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) but with a higher thermal stability and lower sensitivity towards impact and friction. To investigate its polycrystalline properties, differential scanning calorimetry (DSC), powder-X-ray-diffraction (PXRD) and ab initio calculation using the Viena Ab initio simulation package (VASP) were employed.

Construction of New Insensitive Explosives: Fused N5-Chain N1,N3,N5-(1,2,3,4-Tetrazole -5-Nitro)-1,3,5-Triamino-2,4,6-Trinitrobenzene Derivatives

A series of N1,N3,N5-(1,2,3,4-tetrazole-5-nitro)-1,3,5-triamino-2,4,6-trinitrobenzene derivatives containing fused N5-chain were investigated theoretically. Density functional theory has been employed to calculate their geometric, electronic structures, band gaps, and heats of formation at the B3LYP/6-31G** level. The detonation performance was evaluated by using Kamlet-Jacobs equations based on the calculated densities and HOFs. The thermal stability of these compounds was investigated by bond dissociation energies, energy gaps and molecular electrostatic potentials. Results show that there are good linear relationships between detonation velocity, detonation pressure and the number of nitro groups. Most of the designed derivatives have higher detonation velocity (D), detonation pressure (P), and specific impulse (Isp) than those of RDX. D and Isp of molecule L even outperform those of CL-20. Some of the title molecules have higher h50 (impact sensitivity) than RDX (except for D, H, L). According to the quantitative standard of energy and stability as insensitive high energetic materials (IHEMs), molecules I and J essentially satisfy this requirement. These results provide basic information for molecules design of novel IHEMs.

Formation of trinitromethyl functionalized 1,2,4-triazole-based energetic ionic salts and a zwitterionic salt directed by an intermolecular and intramolecular metathesis strategy

Ionic salts of 5,5′-bis(trinitromethyl)-3,3′-bi-1H-1,2,4-triazole and an unexpected energetic zwitterion 5-diazonium-3-trinitromethyl-1,2,4-triazolate were synthesized via an intermolecular and intramolecular metathesis strategy. Compared with its ammonium (6), hydrazinium (7) and hydroxylammonium (8) salts, 5,5′-bis(trinitromethyl)-3,3′-bi-1H-1,2,4-triazole (5) exhibits lower sensitivities (IS: 22.5 J and FS: 252 N). It is worth noting that energetic salt 8 exhibits a high density of 1.97 g cm−3 and an excellent calculated detonation velocity of 9468 m s−1, and that the energetic zwitterion 5-diazonium-3-trinitromethyl-1,2,4-triazolate (14) exhibits a high density of 1.893 g cm−3 and an excellent calculated detonation velocity of 9317 m s−1, which are both superior to that of HMX (9254 m s−1).

Theoretical Screening of Novel 5-picrylamino- 1,2,3,4-tetrazole (PAT) and 5,5′-styphnylamino-1,2,3,4-tetrazole (SAT) Derivatives: A New Molecular Design Strategy of Multi-Nitrogen Energetic Materials by Introducing Intermolecular Hydrogen Bonds and π–π Stacking Interactions

ABSTRACT On the basis of a design strategy that results in the introduction of intramolecular hydrogen-bonds and π–π stacking interactions leading to low-sensitive and high-energy materials (LSHMs), –NH2/–NO2 fused derivatives of 5-picrylamino- 1,2,3,4-tetrazole (PAT) and 5,5′-styphnylamino- 1,2,3,4-tetrazole (SAT) were designed and investigated theoretically. Density functional theory has been explored to investigate the geometric, electronic structures, band gaps, and heats of formation. The detonation performance was evaluated by using Kamlet-Jacobs equations based on the calculated densities and enthalpy of formation (EOF). The thermal stability of these compounds was studied by calculating bond dissociation energies and energy gaps. Proper numbers of 5-aminotetrazole (5-AT) moieties can enhance the EOFs of explosives, further improving the detonation performance as well as nitro group. Though introducing more nitro-groups into TATB frameworks, NH-moieties can retain the intramolecular hydrogen-bond, which can enhance the crystal-packing and physico-chemical stability. Meanwhile, noncovalent interaction (NCI) plots reflects that intermolecular interaction also has a crucial influence on the mechanical sensitivity for the designed derivatives, except for the energy gap (ΔE) and bond dissociation energy (BDE). UV/Vis spectra and 15N isotropic magnetic shielding were further computed for characterizing and predicting the molecular structure and reaction mechanism towards the future experiments. The predicted performance implies that the designed molecules are expected to be promising candidates for multi-nitrogen energetic materials.

Synthesis, and single crystal structure of fully-substituted polynitrobenzene derivatives for high-energy materials

New energetic fully-substituted polynitrobenzene derivatives were synthesized via the reaction of 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) with 1,2,4-triazole followed by the nucleophilic substitution of the halo groups by aqueous ammonia or sodium azide. These compounds were charactered by 1H NMR, 13C NMR and HRMS. Additionally, the structures of amino derivatives 6, 8 and azido derivative 7 were further confirmed by single crystal X-ray diffraction analysis. Their decomposition temperatures and impact sensitivities were also determined. The derivative 1,2-di-1H-triazol-4,6-diamino-3,5-dinitrobenzene (8) exhibits good thermal stability (Td = 314 °C) and low impact sensitivity (IS = 30 J), which are both superior to that of TNT (Td = 295 °C, IS = 15 J). These synthesized compounds showed high heat of formation ranging from 31.77 to 1014.68 kJ mol−1, and reasonable detonation velocities and pressures.