Synthesis of caged high-energy-density fuel as potential high-performance energetic additive for liquid aerospace fuel.

High-energy-density (HED) fuels have drawn substantial attention for volume-limited aerospace vehicles because they can provide high propulsion energy. Herein, we report a route for synthesis of HED fuel pentacyclo[5.3.0.02,5.03,9.04,8]decane (PCD) with strained structure by photoinduced intramolecular [2 + 2] cycloaddition of dicyclopentadiene (DCPD). The reaction conditions, like photosensitizer, solvent, concentration, temperature and light intensity, were optimized for achieving the best photochemical performance, with the high DCPD conversion of 95.89% and high PCD selectivity of 62.08%. The triplet quenching and phosphorescence quenching results show that DCPD cycloaddition proceeds under the photosensitizer photoexcitation, triplet-triplet energy transfer, cyclization and relaxation. Moreover, a reaction kinetic model is established with the reaction rate constant being correlated with light intensity, with the pseudo reaction kinetics parameters and reaction rate equations obtained. As a caged fuel, PCD possesses both high density (1.066 g/cm3) and high volumetric neat heat of combustion (44.43 MJ/L), which is very promising to blend with current high density liquid fuels to obtain high-performance fuels for practical application. • PCD is synthesized by a one-step photoinduced intramolecular [2 + 2] cycloaddition. • The triplet sensitization mechanism was proposed. • A reaction kinetic model correlated with light intensity is established. • PCD exhibits both high density and high volumetric neat heat of combustion. • PCD is a promising high-energy additive for practical application. [ABSTRACT FROM AUTHOR]