Interstate Crossing-Induced Chemiexcitation as the Reason for the Chemiluminescence of Dioxetanones

Authors

  • Dr. Luís Pinto da Silva,

    1. Centro de Investigação em Química (CIQ-UP), Departamento de Química e Bioquímica, Universidade do Porto, Campo Alegre 687, 4169-007 Porto (Portugal)
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  • Prof. Dr. Joaquim C. G. Esteves da Silva

    Corresponding author
    1. Centro de Investigação em Química (CIQ-UP), Departamento de Química e Bioquímica, Universidade do Porto, Campo Alegre 687, 4169-007 Porto (Portugal)
    • Centro de Investigação em Química (CIQ-UP), Departamento de Química e Bioquímica, Universidade do Porto, Campo Alegre 687, 4169-007 Porto (Portugal)
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Abstract

The decomposition reaction of dimethyl-1,2-dioxetanone in dichloromethane was studied by using a DFT approach. The low efficiency of triplet and singlet excited-state formation was rationalised. A charge-transfer process was demonstrated to be involved in the chemiluminescence process. Present and previous results allow us to define an interstate crossing-induced chemiexcitation (ICIC) mechanism for the chemiluminescence of dioxetanones. Charge transfer is needed to reach a transition state, in the vicinity of which direct population of excited states is possible. The chemiexcitation process is then governed by singlet/triplet intersystem crossings. Structural modifications then modify the rate of these crossings and the singlet ground and excited-state interaction, thereby modulating the efficiency of this process and the spin of the resulting products.

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