Dioxetans decomposition: correlation

Fig. 8a. State correlation diagrams for dioxetan decomposition to carbonyl compounds.

Subsequent studies (63,64) suggested that the nature of the chemical activation process was a one-electron oxidation of the fluorescer by (27) followed by decomposition of the dioxetanedione radical anion to a carbon dioxide radical anion. Back electron transfer to the radical cation of the fluorescer produced the excited state which emitted the luminescence characteristic of the fluorescent state of the emitter. The chemical activation mechanism was patterned after the CIEEL mechanism proposed for dioxetanones and dioxetanes discussed earher (65). Additional support for the CIEEL mechanism, was furnished by demonstration (66) that a linear correlation existed between the singlet excitation energy of the fluorescer and the chemiluminescence intensity which had been shown earher with dimethyl dioxetanone (67). 

Figure 14.11. (a) Orbital and (b) state correlation diagrams for the decomposition of dioxetane. The observed chemiluminescence may be due to intersystem crossing (ISC) to the triplet manifold in the region denoted by the shaded circle in (b). 

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