The evolution of energetic materials science poses new challenges centered on developing advanced technologies and structures. A new azo-bridged compound with pyrazole and tetrazole moieties featuring nitro groups was synthesized by electrochemical homocoupling of C-amino pyrazole. Green and pollution-free, electrochemical preparation overcomes C-aminopyrazole’s high oxidative sensitivity, effectively avoiding competing pathways like overoxidation, ring degradation, and cleavage under oxidative conditions. The azo-linked four-heterocyclic molecule 3 exhibits encouraging properties as an insensitive energetic material. Compound 3 demonstrates good density (1.86 g/cm3), good detonation velocities (8643 m/s), low impact and friction sensitivity (IS > 40 J, FS > 360 N), and extremely high enthalpies of formation (1301.9 kJ/mol). Theoretical calculations revealed that the low sensitivity of C-linked azopyrazole derivative 3 arises from a reduced surface electrostatic potential and enhanced noncovalent interactions, while the disrupted π-conjugation accounts for its moderate thermal stability. This work provides an efficient green electrochemical synthesis methodology that effectively mitigates the high oxidative sensitivity of C-amino and offers a novel strategy for its coupling reactions in diverse research fields.
Liu et al. (Wed,) studied this question.