Xinghui Jin

Context Energetic materials based on bis(4-nitropyrazole)-bridged nitrogen-rich heterocycles are designed, and their physical and chemical properties are fully investigated. Their heats of formation, detonation performance, and impact sensitivities are fully investigated. The results indicate that the addition of a tetrazole/-N₃ functional group contributes to an increase in the heats of formation of the designed compounds, while the incorporation of a tetrazole/-C(NO₂)₃ functional group is beneficial for enhancing their detonation performance. By comprehensively balancing energy performance and stability, candidate compounds A2 and E2 are screened out since these compounds possess better detonation performance and lower impact sensitivities than those of RDX. To further understand the physicochemical properties of the selected compounds, electronic structures such as frontier molecular orbitals and molecular electrostatic potential are simulated and analyzed. Method The optimization of the designed compounds is performed with the Gaussian 16 program suite using the DFT-B3LYP method at the 6-311G(d,p) level. Multiwfn_3.8_dev is used to compute molecular surface properties. Employing the VMD program, the molecular electrostatic potential (ESP) distributions for compounds A2 and E2 are plotted. The initial decomposition mechanism and total decomposition process of A2 are investigated using the CASTEP code.

A series of K‐6 based energetic compounds are designed by the addition of the characteristic structures of NQ and FOX‐7. Density functional theory calculations at the B3LYP/6‐311G(d,p) level are performed to predict the frontier orbital energy, heats of formation, detonation performance, and impact sensitivity of the designed compounds. It is found that compound C3 possesses the highest value of Δ E _LUMO‐HOMO (5.24 eV), whereas that of compound E6 is the lowest (2.86 eV). Compound C4 has the highest values of Δ H _f,solid (1768.0 kJ mol ⁻¹ ) while that of compound D5 possesses the lowest values (431.1 kJ mol ⁻¹ ). It is concluded that the addition of the N ₃ group combined with the tetrazole ring and NQ structure can improve the values of heats of formation effectively. It is also found that compounds F2 and B3 possess the maximum and minimum values of D and P (compound F2: D, 9.65 km s ⁻¹ , P, 44.0 GPa; compound B3: D, 7.60 km s ⁻¹ , P, 25.0 GPa). There exist 24 compounds that possess higher values of h ₅₀ than that of RDX, whereas there are 16 compounds that possess higher values of h ₅₀ than that of HMX. Finally, compounds A7, A8, and D1 are screened as potential high energy density compounds. Their frontier orbital distribution, thermodynamic properties, electrostatic potential distribution, and area are simulated to give a full understanding of the electronic structure and physicochemical properties of the screened compounds.

As an oxygen‐rich and nitrogen‐rich chemical unit, oxadiazolone is employed to design a series of nitrogen‐rich energetic compounds and their properties, such as frontier molecular orbital, heats of formation, energetic performance, and impact sensitivity, are fully calculated and investigated. The calculated results show that the NN bridge and N ₃ are the most beneficial combinations to increase the heats of formation of the designed compounds, while the combination of CH ₂ CH ₂  bridge and CH(NO ₂ ) ₂ are on the opposite side. However, the addition of CH ₂ NH bridge and C(NO ₂ ) ₃ is the most beneficial combination to increase the values of D and P . Finally, compounds E8 and F8 are screened as potential high‐energy‐density materials since these compounds possess excellent detonation performance and higher values of impact sensitivity than those of RDX. The distribution of frontier molecular orbital and electrostatic potential on the surface of compounds E8 and F8 are simulated to reveal the relationship between the physicochemical properties and electronic structures.

A series of high energy density compounds are designed by altering the triazole, tetrazine, oxadiazole rings and energetic groups (such as −CN, −N₃, −NH₂, −NHNH₂, −NO₂, −NHNO₂, −C(NO₂)₃, −CH(NO₂)₂) into 2,4,5‐trinitro‐imidazole skeleton. Their structures are optimized by density functional theory (DFT) methods at B3LYP/6‐311G (d,p) method. Based on the optimized structures, the impact of different rings and energetic groups on their energy gaps, heats of formation, detonation performance and sensitivities are investigated. The results show that compound F4 possesses the highest values of heats of formation due to their high nitrogen content. However, compound F2 possesses the highest values of detonation pressure and detonation velocity which indicates that the detonation performance are determined by values of density rather than those of heats of formation. Taking both detonation performance and impact sensitivities into consideration, compounds B4, C4, F4, I4, J4 and J8 are screened as high energy density compounds due to their excellent detonation performance and acceptable sensitivities compared to those of RDX. Finally, the distribution of frontier molecular orbital, the electrostatic potential area distribution, thermodynamic properties and weak interactions of the screened compounds are fully investigated.

A series of bridged triazolo[4,5‐d]pyridazine based energetic materials were optimized at B3LYP/6‐311G(d, p) level of density functional theory (DFT), and their detonation properties and sensitivities were calculated. The results show that the NN bridge/N₃ group were beneficial to improve values of heats of formation while NN bridge/C(NO₂)₃ group can improve detonation properties remarkably. In view of the sensitivities, compound F2 possesses the minimum values of impact sensitivity which reveals that NHNH bridge/C(NO₂)₃ group will decrease the stability of the designed compounds. Take both of detonation properties and sensitivities into consideration, compounds C8, E7, E8, F8 were screened as candidates of potential energetic materials since these compounds possess similar detonation properties and sensitivities values to those of RDX. All the calculated results were except to shine lights on the design and synthesis of novel high energy density materials.

In pursuit of energetic materials with equal detonation properties and sensitivities compared to those of HMX and RDX, a series of 3,6‐dinitropyrazolo‐[4,3‐c]pyrazole‐based energetic compounds were designed, and density functional theory method was carried out to investigate the frontier molecular orbital, heats of formation, energetic properties, and impact sensitivities of the designed compounds. The results show that all the designed compounds possess high positive heats of formation range from 618.8 (A4) to 1934.3 kJ mol⁻¹ (E2) and the –N₃ energetic group was the most effective unit to improve the values of heats of formation. Values of oxygen balance of compounds E8 and F8 were zero and possess the most ideal oxygen balance. The calculated detonation properties indicate that the –C (NO₂)₃ group was the most useful group to enhance the densities, detonation velocities, and detonation pressures. Nearly half of the designed compounds possess higher values of h₅₀ than RDX or HMX, which indicates that these compounds will be more stable than RDX and HMX. Based on detonation properties and impact sensitivities, five compounds (D3, D5, E5, F3, and F5) were screened as candidate compounds for high energy density materials. Finally, the distribution of the highest occupied molecular orbitals, the lowest unoccupied molecular orbitals, and electrostatic potential of the screened compounds were simulated to give an evident view on their physicochemical properties.