Preparation and crystallographic characterization of 1H-tetrazole/NaClO₄ energetic cocrystal

Abstract

Cocrystallization is a promising method for generating new energetic materials with improved performances. Herein, a novel energetic cocrystal composed of 1H-tetrazole/sodium perchlorate was prepared using the solvent evaporation method. This cocrystal is characterized as containing organic azole derivatives and an ionic perchlorate salt, which is used as an oxidizer in pyrotechnics. The crystal structure was determined via single-crystal X-ray diffraction. The as-prepared crystal exhibited a lamellar structure consisting of 1H-tetrazole and sodium perchlorate layers. A molecular structure comparison between the cocrystal and pristine ingredients revealed variations in the bond lengths and angles owing to the cocrystallization. The hydrogen bond formed by adjacent tetrazole rings was strengthened. The 1H-tetrazole/sodium perchlorate cocrystal was structurally compared with crystals previously reported to the Cambridge Structural Database including sodium perchlorate in lamellar structures. The lamellar structure of the cocrystal exhibited weak layer-to-layer interactions compared with those of the other crystals. Fourier transform infrared and Raman spectroscopy analyses were conducted, and the relationship between the spectroscopy results and the crystal/molecular structure are discussed. The results of the spectroscopic analyses exhibited peak shifts that indicate structural changes in bond lengths and angles owing to the cocrystallization.