Photoinduced charge separation of methylphenothiazine in microporous metalsilicoaluminophosphate M-SAPO-n (M = Cr, Fe, Mn, n = 5, 8, 11) materials

Metal silicoaluminophosphate, M-SAPO-n, (M = Cr, Fe or Mn, It = 5, 8, 11) m icroporous materials with incorporated methylphenothiazine are photoionized with 320 nm light at room temperature. Methylphenothiazine cation radicals are produced and characterized by electron spin resonance. Transition meta l ion containing microporous M-SAPO are found to be efficient hosts for the formation and stabilization of methylphenothiazine cation radicals (PC1+). The photoyield is either negligible or not observed in the case of H-SAPO- n materials, indicating that the transition metal ions serve as suitable el ectron accepters and assist in the stabilization of the photoproduced PC1radicals. Chromium containing SAPO materials exhibited the highest photoyie ld among the Cr, Fe, and Mn transition metal ions studied. The photoionizat ion efficiency was found to depend on the nature of the metal ion, the conc entration of the metal ion, and also on the pore size of the microporous SA PO material used.