Dioxetane radical cations in solution. An ESR and cyclic voltammetry study

Oxygenation of α-Methylstyrene with Molecular Oxygen, Catalyzed by 10-Methylacridinium Ion via Photoinduced Electron Transfer

“…The ESR spectrum consists of a single isotropic signal with the g value of 2.0152 showing no detectable hyperfine structure. This ESR feature is in good agreement with that of tertiary alkylperoxyl radicals. , The absence of the proton hyperfine structure suggests the observed peroxyl radical is attributed to neither the peroxyl radical cation nor the dioxetane radical cation in Scheme , since the peroxyl radical cation would exhibit the hyperfine splitting due to the β-proton and since the dioxetane radical cation ( 1 ) has a quite different g value (2.0099) than that of the complexed hyperfine structure . When α-methylstyrene is replaced by styrene, the ESR spectrum obtained under the same experimental conditions as those for the case of α-methylstyrene exhibits a doublet signal which corresponds to the hyperfine structure due to one proton (Figure b).…”

“…40,41 The absence of the proton hyperfine structure suggests the observed peroxyl radical is attributed to neither the peroxyl radical cation nor the dioxetane radical cation in Scheme 1, since the peroxyl radical cation would exhibit the hyperfine splitting due to the β-proton and since the dioxetane radical cation (1) has a quite different g value (2.0099) than that of the complexed hyperfine structure. 42 When R-methylstyrene is replaced by styrene, the ESR spectrum obtained under the same experimental conditions as those for the case of R-methylstyrene exhibits a doublet signal which corresponds to the hyperfine structure due to one proton (Figure 7b). The observed hfs value (a H ) 6.1 G) is in the range 2-8 G reported for secondary alkylperoxyl radicals.…”

Efficient Photocatalytic Oxygenation of Aromatic Alkene to 1,2-Dioxetane with Oxygen via Electron Transfer

“…A deaerated chloroform solution of Acr + -Mes (3.7 × 10 -2 M) with TPE dioxetane (3.0 × 10 -3 M) was irradiated by a high-pressure Hg lamp at 223 K. The resulting ESR spectrum observed at 143 K is shown in Figure a, which exhibits anisotropic signals at g || = 2.020 and g ⊥ = 2.004. The isotropic g value ( g iso ) is determined as 2.009 ± 0.001, , which agrees with the reported value of a dioxetane radical cation (2.0099) . The formation of TPE dioxetane radical cation was also confirmed by photoinduced electron-transfer oxidation of TPE dioxetane with the singlet excited state of 9,10-dicyanoanthracene ( 1 E red * = 1.97 V vs SCE) in frozen deaerated CHCl 3 at 143 K. The resulting ESR signal was virtually same as that shown in Figure a.…”

Photoinduced Reactions of Radical Ions via Charge Separation

“…The isotropic g value (g iso ) is determined as 2.009 ± 0.001, which agrees with the reported value of a dioxetane radical cation (2.0099). 99 The formation of TPE dioxetane radical cation was also confirmed by photoinduced electron-transfer oxidation of TPE dioxetane with the singlet excited state of 9,10-dicyanoanthracene (DCA) ( 1 E * red = 1.97 V vs SCE) in frozen deaerated CHCl 3 at 143 K. 79 The resulting ESR signal was virtually the same as that shown in Figure 4a. 79 The singly occupied molecular orbital (SOMO) of dioxetane radical cation involves O-O antibonding orbital (Figure 4b).…”