Intramolecular assembly of dinitromethyl and bistetrazole: a strategy for constructing advanced and environmentally friendly high-energy density materials

Abstract

Bistetrazoles have received extensive attention from researchers in the field of energetic materials due to their high heat of formation (ΔH_f = 4.06 kJ g⁻¹) and high nitrogen content (N% = 81.14%). In this work, target product 2,2′-bis(dinitromethyl)-2H,2′H-5,5′-bistetrazole (BDNBT), composed of dinitromethyl and bistetrazole, could significantly improve the dilemma of high sensitivity of bistetrazole-derived energetic materials. The two polymorphic forms (α and β) of BDNBT exhibit differences in density and detonation performance among other aspects. The polymorph α of BDNBT with near-zero oxygen balance (OB% = −4.62%) has a crystal density of up to 1.917 g cm⁻³ (193 K) and excellent detonation properties (D = 9480 m s⁻¹ and P = 40.2 GPa), superior to those of polymorph β of BDNBT (ρ = 1.899 g cm⁻³ (193 K), D = 9306 m s⁻¹, and P = 38.5 GPa). In this study, five monovalent cationic salts (4–8) and two divalent cationic salts (9–10) of BDNBT were synthesised and discussed. Among them, energetic 2,4,6-triamino-1,3-dihydroxy-1,3,5-triazine-1,3-diium salts 10 exhibits superior detonation performance to RDX (D = 8795 m s⁻¹ and P = 34.9 GPa) and HMX (D = 9144 m s⁻¹ and P = 39.3 GPa), with a density of 1.904 g cm⁻³, a detonation velocity of 9612 m s⁻¹, an impact sensitivity of 10 J and a friction sensitivity of 120 N. This work provides guidance for future researchers to develop high-energy density materials and enhance material properties through crystal phase transitions.