Hydride- and boron-free solid hypergolic H2O2-ignitophores.

• Novel hydride- and boron-free, air-stable H 2 O 2 -hypergols were prepared and evaluated. • Some of these fuels have high density and showed thermostability up to 343 °C. • Top performing fuel showed Ignition Delay of 7 ms, and Specific Impulse up of 279 s. • Crystal-level DFT calculations allowed to propose Structure-Activity Relationships. • The ignition performance key factor is based on electron density on metal and ligand. The race and competition in aerospace technologies based on environmentally friendly green propulsion systems with green fuels and oxidizers are attracting a significant attention. Development of hybrid propulsion systems that use a hypergolic fuel and green H 2 O 2 oxidizer, capable of deep throttling and restarting from "cold", is a very challenging task. Here, we describe a new synthetic approach for the synthesis and characterization of conceptually new hydride- and boron-free, and air/moisture stable solid H 2 O 2 -hypergols, based on Cu and Co complexes of bis(5-tetrazolyl) amine (H 2 BTA) ligand. Among prepared and evaluated materials, the best performing compound [K 2 (H 2 O) 2 Cu(BTA) 2 ]n (JD-4) was found to exhibit short ignition delay time of 7 ms (with H 2 O 2 , 97%), and high thermostability of 343 °C. Based on obtained ignition results, X-ray crystallography and HASEM software calculations, structure-hypergolic activity-relationship studies were conducted. We found that the electron density difference between Cu and BTA units should be in a specific range (~2) for these compounds to ignite, providing a valuable tool for further development of novel, green, solid fuels for propulsion systems. [ABSTRACT FROM AUTHOR]