Structural Effects on the Intramolecular Electron Transfer Induced Decomposition of a Series of 1,2-Dioxetanes Derived from 9-Alkylidene-10-methylacridans

Article abstract of DOI:10.1021/ja00531a026

A series of 1,2-dioxetanes derived from 9-alkylidene-10-methylacridans, Ar=CR1R2, were studied: 5, R1=R2=phenyl; 1, R1=phenyl, R2=H; 6, R1=R2=H.Thermal decomposition of these dioxetanes in the temperature range -30 to +35 deg C is accompanied by chemiluminescence (CL), N-methylacridone(NMA) fluorescence, with representative room temperature Φ_CL's of 0.11, 0.04, and ca.10^-5 and room temperature lifetimes of ca.2000, ca.60, and ca.6 s, for 5, 1, and 6, respectively.The only triplet states produced in these system is by 1NMA* <*> 3NMA* as indicated by triplet counting experiments.The CL from decomposition of 1 is subject to off/on switching by successive addition of acetic acid and triethylamine.The proposed mechanism involves intramolecular electron transfer (N to peroxide bond) induced decomposition, via a boat conformation, to a dipolar intermediate that partitions between chemiexcitation and nonchemiexcitation pathways.The related low CL levels from decomposition of 1 when prepared by triphenyl phosphite ozonide oxygenation, and the CL enhancement with added triethylamine, are explained.