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In order to explore novel high-energy and green oxidants, oxygen-rich clusters O4−/0 and O6−/0 were investigated by laser-vaporization source, mass spectrometry and theoretical calculations. Most of the low-lying isomers of On−/0 clusters are polyline structures consisting of O2 and O3 units. With one exception, O6, which has a chair-form cyclic structure with D3d symmetry, just like cyclohexane. It has the largest HOMO-LUMO energy gap of the On−/0 (n = 4, 6) clusters. The energy performances of O6 cluster were also estimated, which the density is 2.03 g/cm3, the solid enthalpy of formation is 114.75 kcal/mol, and the theoretical specific impulse (Isp) of H2(L)/O6 cluster is calculated to be 507.78 s.

Cationic zirconium-doped nitrogen clusters were produced by laser ablation of a Zr : BN mixture target and were detected by TOF mass spectrometry. It is found that the mass peak of the ZrN12+ cluster is dominant in the spectrum. The ZrN12+ cluster was further dissociated with 266 nm photons. Extensive structure searches of a cationic ZrN12+ cluster indicate that the ground state structure of ZrN12+ consists of a central Zr atom and six N2 pairs with Oh symmetry. The calculated binding energy of the ZrN12+ cluster is about 0.96 eV, which is in accordance with the result of the photodissociation experiment. The neutral ZrN12 cluster has almost the same geometry, but with D3h symmetry. NBO analysis showed that the molecular orbitals of ZrN12+/0 clusters are mainly composed of Zr 4d and N 2p orbitals. These findings provide rich information for understanding the geometries and the electronic properties of zirconium-doped N clusters, which will offer valuable guidance for the exploration of other metal doped nitrogen clusters.

First principles investigation and Hirshfeld surface analysis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystals have been carried out. The geometrical and electronic structures of TATB molecules in the crystal and gas phases were compared. The Hirshfeld surface analysis of the TATB crystal structure shows that the intermolecular H⋯O interactions make important contributions in stabilizing the TATB crystal, while other intermolecular H⋯N and H⋯C interactions, O⋯O, N⋯O, C⋯O, and C⋯N close contacts also make contributions. QTAIM analyses of the intermolecular interactions in the molecular pairs confirm the presence of these intermolecular interactions based on Hirshfeld surface analyses, indicating that these intermolecular interactions play important roles in the crystal. The reason why the TATB crystal adopts a high energy conformer in which the NO2 and NH2 groups are coplanar with the benzene ring is elaborated. The cooperativity between hydrogen bonding and π⋯π interactions in the TATB crystal is verified and illustrated.

High-energy-density materials (HEDMs) require new design rules collected from experimental and theoretical results and a proposed mechanism. One of the targeted systems is the nitrogen-rich compounds as precursors for possible polymeric nitrogen or its counterpart in a reasonable pressure range. 1H-tetrazole (CH2N4) with hydrogen bonds was studied under pressure by both diffraction and spectroscopy techniques. The observed crystal structure phase transition and hydrogen bond-assisted electronic structure anomaly were confirmed by first-principles calculation. The rearrangement of the hydrogen bonds under pressure elucidates the bonding interactions of the nitrogen-rich system in local 3D chemical environments, allowing the discovery and design of a feasible materials system to make new-generation high-energy materials.

Crystal structure predictions are significant and meaningful for the design of high energy materials since different packing modes can greatly influence their properties, such as energy and safety. In view of the difficulty of organic crystal structure predictions, an alternative strategy was proposed in this work based on the packing similarity of “homologous crystals”. As a case study, the crystal structures of two energetic N-oxides were accurately and rapidly predicted by this strategy, that is, using their O-free analogues with known structures to generate initial crystals. Two rules, molecular similarity and electrostatic matching, were put forward to ensure the packing similarity in the practical applications of crystal structure predictions. Despite the limited number of “homologous crystals” of energetic N-oxides, this study is envisioned to provide a new approach to predict crystal structures of other high energy materials.

A new strategy for the accurate morphology prediction of energetic material crystals was proposed in the theoretical framework of the attachment energy model; namely, the “averaged” attachment ener...

Currently, crystal engineering has attracted much attention as a promising strategy to balance the energy and sensitivity of explosives, such as energetic–energetic co-crystals. A deep understanding of the intermolecular interactions in explosive crystals from a microscopic point of view is meaningful for the development of low-sensitivity and high-energy (LSHE) explosives. Herein, the cooperativity of hydrogen bonds (HBs) in the nitramide (NA) crystal was quantitatively investigated with the aid of computational methods as a prototypical study of LSHE crystals. Two types of HB interactions were identified via both geometry and electron density analysis, and the electrostatic interactions dominantly contribute to the HB formation. The cooperativities of the single HB type and induced by other intermolecular interactions were quantified in various structural models, including linear clusters and layer fragments. The deconstruction of the NA crystal shows that the interaction energy for crystal stabilization was reduced by about 21% in comparison with that of the dimer as a result of an overall anti-cooperativity of the HB interactions, which is energetically unfavored for the formation of explosive crystals due to the weakening of the intermolecular interactions. This prototypical study is aimed to establish a theoretical strategy for further exploration of intermolecular interaction cooperativities in practical LSHE explosives, and is envisioned to open a new perspective to improve the knowledge of the crystal structure-sensitivity relationship.

we present a novel surfacing coating to resolve the stability of α-AlH3. Inspired by the strong chemical adhesion of mussels, the polymerization of dopamine was first introduced to coat α-AlH3 through a simple situ polymerization. The α-AlH3 was used as a substrate. In-depth characterizations confirmed compact formation with PDA on α-AlH3 surface. The coated α-AlH3 sample was characterized by XRD XPS and SEM . The results show that a strong PDA film is formed on the surface of α-AlH3, the PDA@α-AlH3 retained primary morphology. The crystal form of α-AlH3 does not change after coated by PDA. The results of XPS analysis show that N1s appears on the material after coated by PDA, indicating that polydopamine is formed on the surface of α-AlH3. The moisture absorption tests show that the moisture absorption rate of α-AlH3 is greatly reduced after being coated with PDA. The excellent intact ability of PDA prevent α-AlH3 reacting with watered in the air. The thermal stability of α-AlH3 before and after coating was analyzed by DSC. This work demonstrates the successful applications of dopamine chemistry to α-AlH3, thereby providing a potential method for the metastable materials.

We present a novel surface coating to resolve the stability of α-AlH

Cationic zirconium-doped nitrogen clusters were produced by laser ablation of a Zr : BN mixture target and were detected by TOF mass spectrometry. It is found that the mass peak of the ZrN12+ cluster is dominant in the spectrum. The ZrN12+ cluster was further dissociated with 266 nm photons. Extensive structure searches of a cationic ZrN12+ cluster indicate that the ground state structure of ZrN12+ consists of a central Zr atom and six N2 pairs with Oh symmetry. The calculated binding energy of the ZrN12+ cluster is about 0.96 eV, which is in accordance with the result of the photodissociation experiment. The neutral ZrN12 cluster has almost the same geometry, but with D3h symmetry. NBO analysis showed that the molecular orbitals of ZrN12+/0 clusters are mainly composed of Zr 4d and N 2p orbitals. These findings provide rich information for understanding the geometries and the electronic properties of zirconium-doped N clusters, which will offer valuable guidance for the exploration of other metal doped nitrogen clusters.

An amphiphilic cationic tripyridiniumylporphyrin monomer, i.e., ZnTrMPyP, was synthesized and copolymerized with acrylamide in water and dimethyl sulfoxide, respectively, to prepare the water-soluble random copolymer P-D and microblock copolymer P-W. The association behavior and fluorescence quenching between the copolymers and tetra(p-sulfonato phenyl)porphyrin (Fe(III)TSPP(Cl)) were studied via absorption and emission spectra. The results showed that relatively discrete pendant groups of ZnTrMPyP within P-D could form a ground state complex with FeTSPP by electrostatic interactions, and both static and dynamic mechanisms were active in this quenching process. In contrast, the microblock porphyrin pendant groups within P-W interacted with FeTSPP as an entity, and static quenching was dominant in this process. Salt effects on the formation of the copolymers and FeTSPP complex were also investigated through the addition of KNO3, and the results showed that this association can be weakened by the electrostatic shielding effect, and the fluorescence quenching constant could be reduced.

A new energetic salt, hydrazinium 5-nitro-3-dinitromethyl-2H-pyrazole, was synthesized using 1-nitro-3-trinitromethylpyrazole and hydrazine as raw materials and fully characterized by IR and NMR spectroscopy, elemental analysis, and X-ray crystallography. The isomerization of N-nitropyrazole in the reaction condition was first reported and the possible mechanism was explained by the density functional theory method. The salt has good density, high positive enthalpy of formation superior to those of the RDX and HMX, and good detonation properties comparable to those of RDX. By denitration and isomerization reactions, the salt gains a better thermal stability and lower sensitivity toward impact and friction compared with its parent compound. Based on an overall energetic evaluation, the salt has a promising future as an alternative explosive. The research also contributes to the synthesis and application of polynitro-substituted N-heterocyclic compounds as energetic materials.

Melting point is a significant property of energetic materials especially for melting cast explosives. Theoretical prediction of melting point is greatly meaningful for design and screening of low-...

Mixed nitrogen-lithium cluster cations LiNn+ were generated by laser vaporization and analyzed by time-of-flight mass spectrometry. It is found that LiN8+ has the highest ion abundance among the LiNn+ ions in the mass spectrum. Density functional calculations were conducted to search for the stable structures of the Li–N clusters. The theoretical results show that the most stable isomers of LiNn+ clusters are in the form of Li+(N2)n/2, and the order of their calculated binding energies is consistent with that of Li–N2 bond lengths. The most stable structures of LiNn+ evolve from one-dimensional linear type (C∞v, n = 2; D∞h, n = 4), to two-dimensional branch type (D3h, n = 6), then to three-dimensional tetrahedral (Td, n = 8) and square pyramid (C4v, n = 10) types. Further natural bond orbital analyses show that electrons are transferred from the lone pair on Nα of every N2 unit to the empty orbitals of lithium atom in LiN2–8+, while in LiN10+, electrons are transferred from the bonding orbital of the Li–Nα bonds to the antibonding orbital of the other Li–Nα bonds. In both cases, the N2 units become dipoles and strongly interact with Li+. The average second-order perturbation stabilization energy for LiN8+ is the highest among the observed LiNn+ clusters. For neutral LiN2–8 clusters, the most stable isomers were also formed by a Li atom and n/2 number of N2 units, while that of LiN10 is in the form of Li+(N2)3(η1-N4).

As a crucial factor, crystal morphology significantly influences the energy and safety properties of energetic materials (EMs). Theoretical prediction of crystal morphology is helpful for scientifically engineering the shape of EM crystals. Currently, the attachment energy (AE) model has been the most widely used method of crystal morphology prediction in the field of EMs. However, the calculation details of modified AE in solution and the physical meaning of some corrected parameters are still unclear, sometimes leading to discrepant predicted results even for the same EM. Here, HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) was taken as a case study and the details of AE calculation were systematically explored. The formula of AE in solution was corrected and a new functional form was proposed. The growth morphology of a HMX crystal in acetone solution was predicted, which is similar to those of the occupancy model, the spiral growth model, and the interfacial structure analysis model. The results reported in this contribution are aiming at the development of a more reasonable and accurate method for predicting the crystal shape of EMs.

VN n+ clusters were generated by laser ablation and analyzed by mass spectrometry. The results showed that VN8+, VN9+, and VN10+ clusters were formed, and the mass peak of VN8+ is dominant in the spectrum. The VN8+ cluster was further investigated by a photodissociation experiment with 266 nm photons. Density functional theory calculations were conducted at the M06-2X/6-311+G(d,p) level to search for stable structures of VN n+ ( n = 8, 9, and 10) and their neutral counterparts. The theoretical calculations revealed that the most stable structure of VN8+ is in the form of V(N2)4+ with D 4h symmetry. The binding energy from the calculation is in good agreement with that obtained from the photodissociation experiments. The global minimum structures of VN8, VN9+/0, and VN10+/0 contain a similar substructure of the N4 ring and exhibit energy properties. The most stable structure of VN9+ is in the form of (η2-N4)V+N(N2)2 with C1 symmetry, while that of VN10+ is in the form of (η4-N4)V+(N2)3 with C s symmetry. For neutral VN8, VN9, and VN10, (η4-N4)V(N2)2, (η4-N4)V(N3)(N2), and (η4-N4)V(N2)3 are their ground-state structures, with decomposition into one V atom, and corresponding quantities of N2 can release energies of about 50.20, 96.28, and 57.76 kcal/mol, respectively.

To understand the crystal–solvent interfacial interactions on the molecular scale, the interfaces between three solvents, that is, acetone, γ-butyrolactone, and cyclohexanone, and three growth faces of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) crystal have been investigated with the aid of theoretical chemistry. The results show that the structural features of crystal faces play a critical role in the energetic, structural, and dynamic properties at the interfaces. For each solvent, the same change trend of some properties among the three faces of HMX crystal is observed, including adsorption affinity, local mass density, and solvent diffusion. For example, the rate of solvent diffusion at the three faces ranks as (011) > (110) > (020) regardless of solvent species. This can be attributed to the similar adsorption sites for solvent incorporation at the same face, which are concentrated at the cavities formed by surficial HMX molecules.

The structural, energetic, and dynamic properties at the interfaces between the five growth faces of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) crystal and acetone (AC) solvent were investigated by computational simulations with an aim to understand the RDX crystal morphology when grown from AC solvent at the molecular level. The simulation results showed that the solvent behavior, such as the mass density distribution, dipole orientation, interaction, and diffusion, was dependent on the structural features of each crystal surface. The binding sites for solvent incorporation at the crystal surface were found and were visually displayed on the basis of occupancy analysis. The typical binding motifs were extracted from the simulation trajectory, with the corresponding binding affinities estimated as (002) ≈ (210) > (200) > (020) > (111) at the M06-2X/6-31++G** level of theory. The theoretical prediction of the morphological importance of each growth face was in reasonable agreement with the experimental RDX morphology grown from AC solvent.

A new family of C-trinitromethyl-substituted pyrazoles was designed and obtained in good yields by the reaction of N2O4 with the pyrazolecarbaldehyde oxime followed by further N-nitration and C-nitration. All of the new compounds were fully characterized by IR and NMR spectroscopy, elemental analysis and differential scanning calorimetry (DSC). Compounds 2 and 3 were further confirmed by X-ray crystallography. These pyrazole derivatives have good densities, positive enthalpies of formation and acceptable sensitivity values. Theoretical calculations carried out using Gaussian 03 and EXPLO5 program demonstrate good to excellent detonation velocities and pressures in the range of ADN and HMX. Compound 3 exhibiting a positive oxygen balance, high specific impulse and moderate thermal stability is a promising high energy density oxidizer.

The rich π-electrons region of graphene enables it to be a good material which can interact with many organic molecules. As a low-sensitivity and high-energy explosive, 1,1-diamino-2,2-dinitroethene and its dimer possess unique characters including hydrogen bonds and π bond which can adsorb on graphene through physisorption. The results suggest that the adsorption energies have a very small difference on the different adsorption sites. Due to the physisorption, the geometrical and electronic properties of 1,1-diamino-2,2-dinitroethene and its dimer vary significantly. The intramolecular as well as intermolecular hydrogen bond strengths are considerably affected due to the π···π interaction of 1,1-diamino-2,2-dinitroethene or its dimer with graphene. The cooperativity between intermolecular hydrogen bonds and π···π interactions is observed which causes wax of intermolecular hydrogen bonds and wane of π···π interactions. The physisorption of 1,1-diamino-2,2-dinitroethene or its dimer also leads to the variation of electronic property of graphene.

While polynitrogens are proposed to be the hyper rocket fuels, many of their properties in the solid states are unclear. Herein, we comprehensively investigated the thermodynamic and kinetic stabilities, polymorphs, and rocket performances of platonic and cubic gauche nitrogens, i.e. tetrahedral N 4 , cubic N 8 , platonic dodecahedral N 20 and cubic gauche nitrogen (cg-N), using the first-principles calculations. The results showed that the dissociation barrier of tetrahedral N 4 in the gas phase (>200 kJ mol −1 ) is high enough to keep stable. It would be a liquid monopropellant under slight external pressure or low temperature. The specific impulse ( I sp ) of tetrahedral N 4 is comparable to that of liquid H 2 /O 2 , but it provides a density of 1.459 g cm −3 with the body centered tetragonal packing. The conversion barrier of cubic N 8 in the gas phase (∼85 kJ mol −1 ) is marginal for stability. It may be a solid at ambient temperature, and its I sp exceeds that of liquid H 2 /O 2 . The crystal density of cubic N 8 is 1.964 g cm −3 with the rhombohedral centered hexagonal packing. The dissociation barrier for stability of platonic N 20 in the gas phase (∼25 kJ mol −1 ) is insufficient, however it possesses a lattice energy above 100 kJ mol −1 . Although the I sp of platonic N 20 is as powerful as that of the liquid H 2 /O 2 , it has a crystal density of 2.132 g cm −3 with the face centered cubic packing. For surface relaxation, cg-N is unstable at the ambient condition with a dissociation barrier of ∼17 kJ mol −1 . While the I sp of cg-N is less than those of platonic nitrogens, its effective impulse ( I ef ) is the best due to an extremely high density of 3.401 g cm −3 . In respect of the thermodynamics, the enthalpies per atom of platonic nitrogens are always higher than those of cg-N and e-N 2 from 0 to 100 GPa.

The physicochemical and energetic properties of 4-(2,2,2-trinitroethyl)-2,6,8,10,12-pentanitro-2,4,6,8,10,12-hexaazaisowurtzitane (1) are investigated. The energetic cage compound exhibits detonation properties comparable to those of HMX, and its impact sensitivity is higher than that of e-CL-20. It shows a significantly higher thermal stability with a decomposition temperature of 227.6 °C than those of the other trinitromethyl-substituted energetic compounds. Its thermal behavior is further investigated using differential scanning calorimetry and accelerating rate calorimetry. The non-isothermal and adiabatic decomposition reaction kinetics of compound 1 are studied, and its thermal safety is evaluated using different criteria including the self-accelerating decomposition temperature, critical temperature of thermal explosion, and five-second delay exploding point.

Since the discoveries of polymeric nitrogen, named cg-N (2004), LP-N (2014), HLP-N (2019), another polymorph named black phosphorus nitrogen (BP-N) was synthesized at high-pressure-high-temperature conditions. The narrow existing pressure region and similar synthesized pressure of BP-N compared with cg-N indicate that the stable energy and enthalpy of formation of these two structures are close to each other, which was confirmed by our theoretical calculation. In order to obtain the pressure region of BP-N phase, pure N2 and TiN/Pb + N2 precursors were used for laser-heating high pressure experiments in diamond anvil cell (DAC), and the phase identity was examined by Raman and XRD mapping. BP-N can be synthesized in the pressure range of 130 GPa to 140 GPa with the assistance of heating absorber. With the decrease of the pressure, BP-N can be quenched to ∼ 40 GPa. The synthesizing pressure–temperature and the stable pressure region of BP-N are important for further exploration of BP-N and its kinetic and thermal dynamic relationship with other polymeric nitrogen, especially cg-N.

Nitrogen-rich lithium cluster cation LiN12+ was generated by laser ablation at specific experimental conditions and analyzed by mass spectrometry. Density functional theory calculations were conducted at the M06-2X/6-311+G(d,p) level to search for stable structures of LiN12+ and its neutral counterpart. The results showed that the most stable structure of LiN12+ is in the form of Li(N2)6+ with Oh symmetry, while that of LiN12 is in the form of Li(N2)4(η1-N4) with C2v symmetry. Natural bond orbital analyses revealed that the stability of LiN12+ is mainly due to the ion—induced dipole interactions between the Li+ ion and N2 molecules.

A comprehensive study of the effect of the structure of pendant chains on the energetic and mechanical properties of nitramino oxetane polymers has been conducted. Enthalpy of formation (EOF), density, glass transition temperature, and elastic moduli were calculated via quantum mechanics and molecular dynamic simulations. It is shown in this study that –CH2 groups are unfavorable for EOFs, densities, and elastic moduli of the polymers, whereas –NCH3NO2 groups are favorable for these parameters. The glass transition temperature (Tg) shows non-monotonic features with increasing –CH2 groups; it reaches a minimum value when the pendant chains consist of 1 or 2 –CH2 groups. Moreover, the location of the pendant chains can strongly affect Tg of the polymers. Our study suggests that the asymmetric structure, distantly located pendant chains and appropriate length of the pendant chains can effectively reduce Tg of the polymers with negligible compromise to other properties.

A novel cationic tripyridiniumylporphyrin monomer, 5-[4-[2-(acryloyloxy)ethoxy]phenyl]-l0,l5,20-tris(N-methyl-4-pyridiniumyl)porphyrinate zinc(II) (ZnTrMPyP), was synthesized, and its self-aggregation in water was studied by UV-vis absorption. The monomer was copolymerized with acrylamide in water and DMSO, respectively, to prepare the water-soluble polymers P-W and P-D. The aggregation behaviour of the copolymers in aqueous solution was investigated by UV-vis absorption and fluorescence emission spectra. The polymer P-D displayed very similar absorption and emission spectra to those of ZnTrMPyP in water, indicating that the polymer chains in P-D have no significant effect on the aggregate structure of ZnTrMPyP in aqueous media. In comparison, two new absorption bands appeared in the Q band range of polymer P-W and its fluorescence spectra red shifted and the fluorescence quantum yield decreased obviously. These characteristics remained unchanged even in a good solvent for the monomer, suggesting that a new aggregation structure for the porphyrin pendants fixed by the covalent bond was formed. According to the different dispersed states of the porphyrin monomer in water and DMSO, the porphyrin pendants should distribute randomly in the P-D polymer chains while having micro-blocky sequences in polymer P-W. The association behaviour between the copolymers and tetra(p-sulfonatophenyl)porphyrin, TSPP, bearing opposite charged substituents were studied by absorption and emission Spectra and further analyzed by the Benesi–Hildebrand and the Stern–Volmer methods. The results showed that relatively discrete porphyrin pendants in P-D formed a 1 : 1 stoichiometric complex with TSPP and both static and dynamic mechanisms were active in this quenching process, while the tightly associated porphyrin pendants in P-W interacted with TSPP as an entirety and static quenching was dominant in this process. This observation was in accordance with their sequential structure. The polymer P-W has a wider absorption range and higher absorption intensity in the long wavelength region than the porphyrin monomer, which can more efficiently absorb light to accomplish light harvesting in water.

VN

N,N′,N″-trihydroxyisocyanuric acid (THICA) with MnO2 promotes the aerobic oxidation of toluene derivatives to corresponding acids in PEG-1000-based dicationic acidic ionic liquid (PEG1000–DAIL). It is demonstrated that THICA/MnO2 is very active and selective and several toluene derivatives are efficiently oxidized to corresponding acids under mild conditions. Both the catalyst and PEG1000–DAIL can be reused after simple separation. A plausible mechanism is also proposed based on the experimental observations. Copyright © 2015 John Wiley & Sons, Ltd.

TiN n+ clusters were generated by laser ablation and analyzed experimentally by mass spectrometry. The results showed that the mass peak of the TiN12+ cluster is dominant in the spectrum. The TiN12+ cluster was further investigated by photodissociation experiments with 266, 532 and 1064 nm photons. Density functional calculations were conducted to investigate stable structures of TiN12+ and the corresponding neutral cluster, TiN12. The theoretical calculations found that the most stable structure of TiN12+ is Ti(N2)6+ with Oh symmetry. The calculated binding energy is in good agreement with that obtained from the photodissociation experiments. The most stable structure of neutral TiN12 is Ti(N2)6 with D3d symmetry. The Ti-N bond strengths are greater than 0.94 eV in both Ti(N2)6+ and its neutral counterpart. The interaction between Ti and N2 weakens the N-N bond significantly. For neutral TiN12, the Ti(N3)4 azide, the N5TiN7 sandwich structure and the N6TiN6 structure are much higher in energy than the Ti(N2)6 complex. The DFT calculations predicted that the decomposition of Ti(N3)4, N5TiN7, and N6TiN6 into a Ti atom and six N2 molecules can release energies of about 139, 857, and 978 kJ mol-1 respectively.

In order to discover more potential high energy compounds, five computer-aided design methods were founded, and 20 high energetic compounds based on the 1,2,3,4-tetrazine-1,3-dioxide frame were designed. The first step of computer-aided design methods was to design new frame M. Three combination rules were invented, they were simple double-points rule, complicated double-points rule, and complicated multi-points rule. The second step of computer-aided design methods was to design 1,2,3,4-tetrazine 1,3-dioxides derivants by connecting M to 1,2,3,4-tetrazine-1,3-dioxides. Two combination rules were invented, they were simple single-points rule and double-points rule. All the structures are ring-fused or caged compounds including 1,2,3,4-tetrazine-1,3-dioxide. In these compounds, almost half of them have positive or zero oxygen balances, and the nitrogen contents of 17 compounds are over 40%. The densities and detonation velocities of all compounds are over 1.98 g cm−3 and 9500 m s−1 respectively. -N = N- group and -NO2 group have a major contribution to enthalpy of formation, detonation heat, and power index. -O- group and -ONO2 group have the main contribution to density, detonation velocity, and detonation pressure.

Molecular dynamics simulations have been performed to understand the adsorption behavior of acetone (AC) solvent at the three surfaces of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctan (HMX) crystal, i.e. (011), (110), and (020) faces. The simulation results show that the structural features and electrostatic potentials of crystal faces are determined by the HMX molecular packing, inducing distinct mass density distribution, dipole orientation, and diffusion of solvent molecules in the interfacial regions. The solvent adsorption is mainly governed by the van der Waals forces, and the crystal-solvent interaction energies among three systems are ranked as (020)≈(110)>(011). The adsorption sites for solvent incorporation at the crystal surface were found and visualized with the aid of occupancy analysis. A uniform arrangement of adsorption sites is observed at the rough (020) surface as a result of ordered adsorption motif.

The novel primary explosive tetranitrodiglycoluril (TNDGU) was synthesized from glycoluril dimer. It was fully characterized by using NMR (1H, 13C), IR spectroscopy, and elemental analysis. X-ray diffraction revealed that the crystals of TNDGU belong to triclinic system with space group P. The thermal behavior of TNDGU was studied using DSC methods. TNDGU exhibited good thermal stability with a decomposition temperature of 284.8 °C. TNDGU was also more resistant to hydrolysis compared to other nitrourea analogues. Additionally, density, enthalpy of formation, detonation velocity (VOD), and detonation pressure of TNDGU were predicted and it was found that TNDGU is a potential powerful explosive with a calculated density of 1.93 g cm−3, a detonation velocity of 8305 m s−1 and low sensitivity to electric discharge.

The structure of hydrazinium 3,5-dinitroamine-1,2,4-triazole (HDNAT) was investigated with infrared (IR), mass spectrometry, 13C-NMR, scanning electron microscopy (SEM), and X-ray crystallography. The crystal density of HDNAT was determined as 1.91 g/cm3 using X-ray diffraction. The crystal belongs to a monoclinic system with the space group P2(1). The thermal decomposition process of HDNAT was investigated via thermogravimetry–differential thermal analysis (TG-DTA) at a heating rate of 10 K/min and differential scanning calorimetry (DSC) under nonisothermal conditions. The decomposition kinetic and thermodynamic parameters were obtained by the Kissinger and Ozawa method. HDNAT can be analyzed by using a C18 high-performance liquid chromatography (HPLC) column with water : acetonitrile : trifluoroacetic acid (97/3/0.1, v/v/v) as the mobile phase and a capacity factor of 1.33.

Two novel energetic compounds, 3,4-bis(1′,2′,4′-triazole-3′-yl)furoxan (BTAF) and 3,4-bis(1′-nitro-1′,2′,4′-triazole-3′-yl)furoxan (BNTAF), were prepared and their structures were characterized by IR, 1H NMR, 13C NMR, MS techniques and elemental analysis. The properties of BTAF and BNTAF were estimated. The predicted performance data of BTAF are as follows: density (measured) is 1.75 g/cm3, nitrogen content 50.9%, detonation velocity 7277 m/s, detonation pressure 20.1 GPa and enthalpy of formation +419.7 kJ/mol. The predicted performance data of BNTAF are as follows: density is 1.84 g/cm3, nitrogen content 45.2%, enthalpy of formation +841.5 kJ/mol, detonation velocity 8490 m/s and detonation pressure 32.4 GPa. The main themal properties of BTAF and BNTAF were analyzed by DSC and TG techniques, the results show that BTAF melts with concomitant decomposition at 188.8°C, the melting point of BNTAF is at 99.2°C and its first decomposition temperature is 139.2°C.

Two tetrazole salts, hydroxylammonium 2-dinitromethyl-5-nitrotetrazolate (HADNMNT) and dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (HATO), were synthesized and characterized. HADNMNT is a new compound, whose structure was determined by 15N NMR experimentally and GIAO calculation, the thermal decomposition temperature, the explosion probabilities of impact sensitivity, and friction sensitivity of which were tested to be 141.9 °C, 96 %, and 100 %, respectively. The detonation parameters of HADNMNT were predicted to be equal to those of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). It was found theoretically that HADNMNT is a potential oxidizer for composite propellants to replace ammonium perchlorate (AP), 1,3,5-trinitro-1,3,5-triazinane (RDX), HMX, and 2,4,6,8,10,12-hexanitro-,2,4,6,8,10,12-hexazaisowurtzitane (CL-20). Safety tests for HATO were performed, and results showed that HATO exhibits excellent thermal stability (the decomposition temperature is 230.3 °C, and the volume of the released gas is 0.30 mL·g−1 at 100 °C for 48 h) and low mechanical sensitivities (the explosion probabilities of impact sensitivity and friction sensitivity are 16 % and 24 %, respectively). The compatibilities of HATO with hydroxyl-terminated polybutadiene (HTPB), AP, RDX, and aluminum powder (Al) were reexamined to be good, using the vacuum stability test. Results from comparative study of HATO and RDX as ingredient for composite propellant showed that the composite propellant composed HATO offer the advantages of high burning rate and low mechanical sensitivities.

In order to study the effects of N-oxide on structure and performance, six categories of energetic compounds were systemically investigated. The results indicated that the C-C bonds in the rings were shortened, and the C-N bonds close to the N → O bond were elongated when N atoms was oxidized to form N → O bonds. N → O bonds can increase the densities of most categories of compounds, and the increment will increase with the number of N → O bonds. As to their detonation performances, almost all categories of compounds had an increased trend, except for some NO2-, NHNO2- and ONO2-substituted compounds. The contribution of 1,2,3,4-tetrazine and 1,2,4,5-tetrazine to performances was better than that of pyrazine and [1,2,5] oxadiazolo [3,4-b] pyrazine on the whole, and the groups, especially energetic groups, made a huge contribution to performance. When R was a NH2 or ONO2 group, all compounds had lower impact sensitivities, and thus represent candidates for novel energetic compounds. However, other than the sixth category of compounds, all compounds had higher impact sensitivities when R was a NO2 or NHNO2 group, and have little significance in application.

An operationally simple, efficient, and environmentally benign synthesis of 1,3,5-triacylperhydro-1,3,5-triazines in good yields by reaction of different organic nitriles and trioxane in the presence of phenylsulfonic acid functionalized mesoporous silica under mild conditions was examined. The yields of the corresponding 1,3,5-trisubstituted perhydro-s-triazines synthesized from acetonitrile, propionitrile, butyronitrile, benzonitrile, and 1.3.5-trioxane were 95.7%, 96.1%, 84.2%, and 98.1%, respectively. The products were characterized by 1H NMR, infrared, mass spectrometry, and elemental analysis. The mechanism of the formation of 1,3,5-triacylperhydro-1,3,5-triazines in acidic conditions was also described using a model reaction of butyronitrile with trioxane.