Molecular and Crystal Features of Thermostable Energetic Materials: Guidelines for Architecture of “Bridged” Compounds.

DFT calculation and data analysis on molecular and crystal level features of 60 reported EMs allowed us to define key descriptors that are characteristics of these compounds’ thermostability. We see these descriptors as reminiscent of “Lipinski’s rule of 5”, which revolutionized the design of new orally active pharmaceutical molecules. The proposed descriptors for thermostable EMs are of a type of molecular design, location, and type of the weakest bond in the energetic molecule, as well as specific ranges of oxygen balance, crystal packing coefficient, Hirshfeld surface hydrogen bonding, and crystal lattice energy. On this basis, we designed three new thermostable EMs HL3, HL7, and HL9, which were synthesized, characterized, and evaluated in small-scale detonation experiments. The best overall performing compound HL7 exhibited an onset decomposition temperature of 341 °C and has a density of 1.865 g cm^–3, and calculated VOD and Pd were 8517 m s^–1 and 30.6 GPa, respectively. Considering HL7’s safety parameters [IS = 22 J; FS = 352; and ESD = 1.05 J] and the results of detonation experiments, the proposed guidelines should further promote the rational design of novel thermostable EMs, suitable for deep well drilling, space exploration, and other defense and civil applications.