Synthesis And Properties Of DCBNT And Crystallization Of CBNT

In recent years,energetic ion salts have become a research hotspot in the field of high energy materials due to their high enthalpy of formation,low vapor pressure,low volatility and low toxicity.Carbonic dihydrazidinium bis[3-（5-nitroimino-1,2,4-triazolate）]（CBNT）,as a typical energetic ion salt and a promising material,the density and calculated detonation velocity of is 1.95 g·cm^-3 and 9399 m·s^-1 respectively,which are comparable to HMX and RDX.In view of the lack of reports on the crystal structure and thermodynamic parameters of CBNT at present,the single crystal culture of CBNT was carried out in various solvents.Based on CBNT,a new energetic triazole ionic salt-dicarbohydrazide bis[3-（5-nitroimino-1,2,4-triazole）]（DCBNT）was synthesized.Moreover,thermodynamic parameters（solubility,enthalpy of solution,dissolution entropy,etc.）,explosion parameters and properties of DCBNT were tested,which provided theoretical and experimental basis for its further application.The specific work of this paper is as follows:（1）Based on the molecular structure of CBNT,a new energetic triazole ionic salt-DCBNT was designed and synthesized from the idea of anion-cation ratio.It was character-ized by single crystal X-ray diffraction,elemental analysis,infrared spectroscopy and nuclear magnetic resonance.The results proved to be credible.（2）The newly synthesized DCBNT was analyzed by TG-DSC at 10°C/min.The ther-mal decomposition of DCBNT was explored and the non-isothermal kinetics of DCBNT at 5,10,15 and 20°C/min was also analyzed.The results show that the main decomposition peak temperature of DCBNT is near 232°C,which is higher than that of CBNT（222°C）,indicat-ing that the thermal stability of DCBNT is better than that of CBNT.（3）The explosion parameters and performance of the newly synthesized DCBNT were tested.The results show that the detonation velocity and pressure of DCBNT are 9234.87m/s and 31.71GPa,respectively.The impact sensitivity is>40 J and the friction sensitivity is 216N.This indicates that DCBNT has low sensitivity and can be classified as low-sensitivity and high-energy explosive.（4）Using Crystal SCAN system tested the solubility of DCBNT in common solvents at290 K to 360 K.It was found that the solubility of DCBNT in all of these solvents increased with increasing temperature.The solubility data of DCBNT in pure solvent and mixed solvent were correlated by Apelblat model,Yaws model and Polynomial model.The fitting results of the three models were basically the same.The Gibbs free energy,enthalpy,entropy and so on were obtained by Apelblat equation analysis.The thermodynamic parameter values of the process indicate that the dissolution of DCBNT in all of these solvents is endothermic and that enthalpy is a major contributor to the standard Gibbs free energy.（5）CBNT was crystallized in 11 pure solvents under different conditions by solvent screening method.Two crystals,CBNT·2H₂O and H₂BNT·2DMSO,were found in H₂O and DMSO,respectively.Furthermore,H₂BNT·2H₂O and[NH₂（CH₃）₂⁺]₂[BNT^2-]·2H₂O crystals were prepared in a mixed solvent of BL/H2O and DMF/H2O（volume ratio=1:1）.The crystal structures of the four new crystals were confirmed by single crystal X-ray diffraction.At the same time,a brief analysis of the interactions in the crystals was carried out,and the possible mechanisms of the appearance of these crystal structures were analyzed.The molecular inter-actions of these new crystals were further analyzed by theoretical simulations of Hirsfield surface and molecular electrostatic potential to explain the evolution of these crystal structures.