Theoretical Study of the Chemiluminescence Mechanism of Dewar Dioxetane
(English)Manuscript (preprint) (Other academic)
Light emission from the heating of Dewar benzene was first reported by McCapra (McCapra, PureAppl. Chem. 1970, 24, 611–629). Since most of the chemiluminescence reactions occur through anO-O cleavage, light observed through the thermal decomposition of Dewar benzene was suggested to becaused by the chemiluminescence mechanism of a dioxetane-based intermediate produced after oxidation.However, no prove of this proposal has been suggested so far and the details of the mechanism are thusunknown. In this paper, thermally activated decomposition mechanism of Dewar dioxetane has been studiedby the multiconfigurational CASPT2//CASSCF approach, and accurate reaction path descriptions havebeen provided for a two-step biradical mechanism consisting of O1-O’1and C2-C’2ruptures based onminimum energy path and intrinsic reaction coordinate computations. A radiationless decay path has beendetermined for the molecule along the excited triplet state, while in the excited singlet state the systemevolves toward an equilibrium structure that might be responsible of the light emission. This findingsprovide clues for rationalizing the observed light emission and point to higher efficiency of fluorescencethan triplet emission. Furthermore, the study allows to understand the effect of conjugated double bondsadjacent to the dioxetane moiety in the chemiluminescence mechanism of dioxetane.
IdentifiersURN: urn:nbn:se:uu:diva-232217OAI: oai:DiVA.org:uu-232217DiVA: diva2:747019
ProjectsChemiluminescence, Multiconfigurational Methods, Dewar Dioxetane