Determining the ground and excited-state decomposition mechanisms of 1,2-dioxetane is essential to understand the chemiluminescence and bioluminescence phenomena. Several experimental and theoretical studies has been performed in the past without reaching a converged description. The reason is in part associated with the complex non-adiabatic process taking place along the reaction. The present study is an extension of a previous work in which a two-step mechanism was proposed for the chemiluminescence involving asynchronous O-O and C-C bond dissociations. New high-level multi-state multi configurational reference second order perturbation theory calculations and ab initio molecular dynamics simulations at constant temperature are performed in the present study, which provide further details on the mechanisms and allow to rationalize further experimental observations. In particular, the new results explain the high ration of triplet to singlet dissociation products (see Fig ). This study reveal the difficulties in dynamics simulations around an extended internal conversion seam and interstate crossing hidden in an entropic trap - key elements of the chemiluminescence of 1,2-dioxetane.

Non-adiabatic process in 1,2-dioxetane

247th National Meeting (2014)

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