Studies on Aminodioxetanes as a Model of Bioluminescence Intermediates. 1‐(1‐methyl‐3‐indolyl)‐6‐phenyl‐2,5,7,8‐tetraoxabicyclo[4,2,0]octane, an Aminodioxetane Resulting in Efficient Ultraviolet and Exciplex Chemiluminescence*

Abstract

Abstract— The title aminodioxetane prepared by photooxygenation of 2–(l‐methyl‐3‐indolyl‐3‐phenyl‐1,4‐dioxene is fairly stable at −46°C and gives on warming to room temperature an ultraviolet light at Λmax 320 nm, which corresponds to 377kJ/mol; the highest energy ever observed among the efficient chemiluminescent compounds. The efficiency of chemiluminescence and excited singlet molecule formation in n‐hexane were 3.6% and at least 50%, respectively. Substitution and solvent effects suggest polar nature of the transition state as expected from the ‘CIEEL’ mechanism. In polar solvents, the dioxetane gives visible light (Λmax 400 nm in dichloromethane) as well as the UV light; the former being quenched by methanol. This is interpreted in terms of an intramolecular exciplex formation between the indole and phenyl groups. This is the first example of an intramolecular exciplex produced by the dioxetane decomposition.

Symposium‐in‐print

“…But in polar solvents, a second strong emission peak appears at longer wavelengths, which is assigned to an intramolecular exciplex (an excited charge-transfer complex) stabilized by the solvent. 20 Finally, the family of dioxetanes of type 5 (Fig. 5) provides many fascinating examples.…”

Solvatochromic Effects on the Electron Exchange Chemiluminescence (CIEEL) of Spiroadamantyl-Substituted Dioxetanes and the Fluorescence of Relevant Oxyanions

“…Indeed, examples of differences between the chemiluminescence and the fluorescence spectra of the authentic CIEEL emitters have been reported for the intramolecular CIEEL of an amino-substituted dioxetane and for the intermolecular CIEEL of the diphenoyl peroxide, which were attributed to the formation of exciplexes. In the former case, the polar media promoted exciplex formation, as manifested by the red-shifted CIEEL emission band, while in nonpolar solvents no exciplex was observed.…”

Estudo dos mecanismos de quimi-excitação na decomposição induzida de peróxidos: uma comparação entre sistemas inter e intramoleculares

“…Porém, foi postulado um mecanismo CIEEL Introdução intramolecular para a decomposição de 1,2-dioxetanos com substituintes facilmente oxidáveis, a qual leva à formação de estados excitados singlete [29][30][31]. Embora os derivados de 1,6-diaril-2,5,7,8-tetraoxabiciclo [2,4,0]octanos (Esquema 2) apresentem comportamento semelhante ao dos dioxetanos simples (alta estabilidade e formação preferencial de estados excitados triplete), a desprotonação resultando no dioxetano fenóxi substituído, altera drasticamente a estabilidade do composto (a -30°C; t 1/2 passa de 17 anos para alguns segundos) e observa-se um relâmpago de luz brilhante azulada [32].…”