Chemistry of Singlet Oxygen. 37. One-Electron Oxidation of Tetramethylphenylenediamine by Singlet Oxygen

Article abstract of DOI:10.1021/j100397a010

Tetramethylphenylenediamine (TMPD) undergoes a one-electron transfer to (1)O2 in H2O; the formation of TMPD^+. (Wuersters blue) is detected by laser flash spectroscopy.The formation of TMPD^+. is competitively quenched by known (1)O2 quenchers.Furthermore, there is a large increase in TMPD^+. formation in D2O, relative to H2O, as would be anticipated for a (1)O2 reaction.The rate (k_τ) of electron transfer to (1)O2 is shown to be (3.3 +/- 1.5) x 10⁹ M^-1 s^-1, close to the diffusion-controlled limit.The formation of observable ions does not take place in any solvent other than H2O(D2O), or with any other of the electron-rich aromatic amines studied.It is suggested that the formation of observable radical ions depends on the ease of ionization of the substrate and on the solvation of the resulting ions.