Experimental evidence of the occurrence of intramolecular electron transfer in catalyzed 1,2-dioxetane decomposition.
The activation parameters for the thermal decomposition of 13 acridinium-substituted 1,2-dioxetanes, bearing an aromatic moiety, were determined and their chemiluminescence emission quantum yields estimated, utilizing in situ photosensitized 1,2-dioxetane generation and observation of its thermal decomposition kinetics, without isolation of these highly unstable cyclic peroxides. Decomposition rate constants show linear free-energy correlation for electron-withdrawing substituents, with a Hammett reaction constant of ρ = 1.3 ± 0.1, indicating the occurrence of an intramolecular electron transfer from the acridinium moiety to the 1,2-dioxetane ring, as postulated by the intramolecular chemically initiated electron exchange luminescence (CIEEL) mechanism. Emission quantum yield behavior can also be rationalized on the basis of the intramolecular CIEEL mechanism, additionally evidencing its occurrence in this transformation. Both relations constitute the first experimental evidence for the occurrence of the postulated intramolecular electron transfer in the catalyzed and induced decomposition of properly substituted 1,2-dioxetanes.
Ciscato
Luiz Francisco M L
LF
Institut für Organische Chemie und Makromolekulare Chemie, Friedrich-Schiller Universität, Humboldtstrasse 10, D-07743 Jena, Germany.
Bartoloni
Fernando H
FH
Weiss
Dieter
D
Beckert
Rainer
R
Baader
Wilhelm J
WJ
D002384:Catalysis; D004579:Electron Transport; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006573:Heterocyclic Compounds, 1-Ring; D007700:Kinetics; D049449:Luminescence; D015394:Molecular Structure; D011789:Quantum Theory; D013237:Stereoisomerism
D006571:Heterocyclic Compounds; D006573:Heterocyclic Compounds, 1-Ring; C079142:1,2-dioxetane