On the effect of 1,4-diazabicyclo[2.2.2]octane on the singlet-oxygen dimol emission: chemical generation of 1O2)2 in peroxide reactions.

The acetone-catalyzed decomposition of monoperoxysulfate ions, the molybdate ion-induced decay of hydrogen peroxide, and the reactions of N-chlorosuccinimide or N-bromosuccinimide with hydrogen peroxide and of dimethyldioxirane with tertiary amines as well as the thermal decomposition of 1,4-dimethylnaphthalene endoperoxide lead to the chemiluminescence of singlet-oxygen dimol species (1O2)2 emitting at 634 and 703 nm. In contrast to the expected enhancement of (1O2)2 chemiluminescence upon addition of 1,4-diazabicyclo[2.2.2]octane (DABCO) [Deneke, C.F.; Krinsky, N. I. J. Am. Chem. Soc. 1976, 98, 3041. Di Mascio, P.; Sies, H. J. Am. Chem. Soc. 1989, 111, 2909.], quenching has been observed. Our data show that enhancement of singlet-oxygen dimol chemiluminescence is not a general phenomenon and, consequently, DABCO is not a reliable chemiluminescent probe for the presence of (1O2)2 in chemical and biochemical systems.

Singlet-oxygen generation in the catalytic reaction of dioxiranes with nucleophilic anions.

Nucleophilic anions such as Cl(-), I(-), Br(-), t-BuO(-), O(2)(-) and OH(-) efficiently catalyze the decomposition of dimethyldioxirane (DMD) and methyl(trifluoromethyl)dioxirane (TFD). Singlet oxygen ((1)O(2)) is formed in these catalytic reactions, as demonstrated by the characteristic infrared chemiluminescence (IR-CL) at 1268 nm. The yield of (1)O(2) generation, measured by the IR-CL method, lies in the range between 2 and 98%, which depends on the particular anion employed. For the bromide ion, the catalytic decomposition of the dioxirane is in competition with the oxidation of Br(-) to elemental bromine.

On the chemiluminescence in the oxidation of tetravalent uranium to the uranyl ion by dimethyldioxirane.

The reaction of the tetravalent uranium [U(IV)] with dimethyldioxirane (DMD) in strongly acidic water-acetone solutions is accompanied by chemiluminescence (CL) in the visible (Vis) and infra-red (IR) regions. At least three independent reaction pathways are involved in the U(IV)-DMD oxidation: the first entails the non-chemiluminescent oxidation of U(IV) to the uranyl ion (UO(2) (2+)); the second involves the catalytic decomposition of DMD by U(IV) to afford singlet oxygen, as manifested by its characteristic IR-CL; and in the third process, slow Vis-CL (510-540 nm) is emitted, following DMD consumption.