Valence Photoisomerization of 1-Ethoxycarbonyl-1H-Azepine and Its Thermal Reversion. Quantitative Aspects.

摘要

Photolysis of 1-ethoxycarbonyl-1H-azepine in solution at 325 - 385 nm gives a valence isomer with a chemical efficiency of 95% and a quantum efficiency of 0.013. The valence isomer reverts cleanly to azepine at 112 - 145C in an uncatalyzed reaction which is exothermic. The valence isomerization can be driven by sunlight and laser emission at 458 nm and cycled in sequential photochemical and thermal steps. The azepine does not luminesce but the energies of S(1) (reactive) and T(1) (unreactive) excited states can be estimated from sensitization and quenching experiments.