Structural Tailoring of Triazole-Based Hypergolic Metal-Organic Complexes for Enhanced Ignition Performance and Energetic Output.

Most hypergolic metal-organic complexes derived from imidazole suffer from low energy density and specific impulse. Herein, triazole-based hypergolic complexes are structurally modified to boost ignition and energetic properties. Eight complexes with diverse coordination environments, metal cores, and ligand skeletons are fabricated using high-enthalpy 1,2,4-triazole ligands and dicyandiamide as a hypergolic initiator. Cu-DMAT-1 and Cu-DMAT-2 possess Cu3O cores, while Cu-AT-8 features a Cu4O2 cluster; these unique metal cores govern the materials' hypergolic activity. All samples deliver ultra-short ignition delay times (IDT) down to 4 ms against white fuming nitric acid. Cu-AT-8 shows optimal comprehensive performance (IDT = 7 ms, Isp = 271.6 s, ρ = 1.891 g/cm3, Eg = 27.3 kJ/g, IS > 40 J, Td = 161.9°C). The IDT value is positively correlated with the HOMO-LUMO gap and intermetallic distance. These complexes effectively catalyze ammonium perchlorate (AP) decomposition, and the Cu-DMAT-3/AP mixture achieves a low relative standard deviation of 4.66% for combustion delay. Formulations blending the cluster complex, AP, and Al reach a peak Isp of 282.8 s for Cu-AT-8; solid grains burn steadily in air with little residue. Their laser ignition delays (65-134 ms) match well with oxidant-drop test results.