A Time‐Resolved Electron Spin Resonance Study of the Generation Mechanism of the Benzoquinone Anion Radical

Abstract

Abstract The chemically induced dynamic electron polarization (CIDEP) spectra for the photolysis of the p‐benzoquinone (PBQ)/formamide (FM) system in acid, basic, and micellar environments were obtained with a homemade time‐resolved electron spin resonance (TR‐ESR) spectrometer. When the PBQ/formamide was photolyzed, the CIDEP spectrum consisted of strong CIDEP signals of the benzosemiquinone anion radical PBQ•− and weak signals for the benzosemiquinone neutral radical PBQH•. When the PBQ/formamide was irradiated in basic or micellar solution, the CIDEP signal for PBQ•− only was obtained. When the PBQ/formamide was irradiated in acid solution, only the CIDEP signal of PBQH• existed. These experimental results indicate that the anion radical PBQ•− was formed from the dissociation of the neutral radical PBQH• accompanying polarization transfer.