Series of AzTO-Based Energetic Materials: Effect of Different π–π Stacking Modes on Their Thermal Stability and Sensitivity

Abstract

π-Stacking is common in materials, but different π−π stacking modes remarkably affect the properties and performances of materials. In particular, weak interactions, π-stacking and hydrogen bonding, often have a great impact on the stability and sensitivity of high-energetic compounds. Therefore, several of energetic materials based on 1,1′-dihydroxyazotetrazole (1) with a nearly flat structure, such as the salts of aminoguanidine (2), 1,3diaminoguanidine (3), imidazole (4), pyrazole ( 5) and triaminoguanidine (6), and a cocrystal of 2-methylimidazole (7), were designed and synthesized. Based on single-crystal diffraction data, thermal decomposition behaviors, and the mechanical sensitivity test, the compounds of 4, 5, and 7 with face-toface π−π stacking display outstanding thermal stability and insensitivity.

New Method for Predicting the Enthalpy of Salt Formation

“…In general, the thermal correction (the second parts in eqs and ) is about 2 RT = 1.18 kcal mol –1 . This method for estimating the enthalpies of salt formation has recently received great support − due to a simple algorithm for obtaining these parameters. Indeed, for inorganic compounds, the correlation coefficient according to this method is R 2 = 0.94 and predicts well the values of the enthalpies of sublimation of salts; however, in the case of organic salts, this method gives rather large errors, and therefore, the predictive ability of this technique in the absence of experimental reference points is small, so this method can only be used for the primary rough estimate of the enthalpies of formation from the values of the enthalpies of sublimation.…”

Tailoring Transition Metals and Biuret into Laser-Ignitable Energetic Coordination Polymers with Improved Oxygen Balance and Multidentate Coordination Structures

“…The bond length of the coordination bond is 0.19–0.26 nm, and the C, H, O, and N organic compounds are connected through the coordination bond, which can shorten the distance between the molecules, thus effectively increasing the crystal density. − As a result, for nitrogen-rich CPs synthesized by coordination chemistry, using metal ions as nodes can not only more effectively enrich energetic ligands but also improve the energy density and detonation performance of energetic materials; at the same time, the thermal stability and sensitivity of the complexes can be effectively controlled. Due to the above characteristics, most reported energy coordination polymers (ECPs) show good thermal stability, high density, low sensitivity, and high energy content. − Some energetic properties of them (calculated value) are even better than those of CL-20, but their sensitivity is lower than that of TNT, which reaches a unity between high energy and low sensitivity. Therefore, these ECPs have been a hot topic in the study of energetic materials. − …”

Recent Progress on Synthesis, Characterization, and Performance of Energetic Cocrystals: A Review

“…Energetic materials (EMs), generally composed of carbon, hydrogen, oxygen, and nitrogen atoms, are a class of substances that release a huge amount of energy in a transient manner while undergoing a self-decay phenomenon [ 1 , 2 ]. Classified as explosives, propellants, and pyrotechnics, EMs find a wide range of applications both in civil and military sectors [ 3 , 4 ]. Trinitrotoluene (TNT), 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) are some of the classic examples of EMs [ 5 , 6 ].…”