Activation parameters and excitation yields of 1,2‐dioxetanes of photogenotoxic interest

Abstract

AbstractThe chemiluminescent decomposition of functionalized 1,2‐dioxetanes was examined in toluene solution. Activation energies were measured by isothermal and nonisothermal kinetic methods. Quantum efficiencies were determined by Stern‐Volmer kinetics, using the fluorescers 9,10‐dibromo‐ and 9,10‐diphenylanthracene for the triplet and singlet excitation yields. The derivatives of 3‐hydroxymethyl‐3,4,4‐trimethyl‐1,2‐dioxetane (1a) have free energies of activation (ΔG≠) of ca. 25 kcal/mol, but the ΔG≠ values of the annelated benzofuran‐type dioxetanes (5) are ca. 1 kcal/mol lower. There exists a reasonable correlation between the free energies of activation (ΔG≠) for the thermal decomposition of the dioxetanes and their triplet excitation flux (EpT).