Publication

Abstract : The photogeneration of singlet oxygen (1O2) by tetrasodium salt of meso-tetrakis(4-sulfonatophenyl)porphyrins (H 2TPPS) and some of its metal complexes (MTPPS; M = Cd2-, Zn2+), immobilized on cationically functionalized polystyrene (PS) beads, was studied. The generation of 1O2 was monitored by a N,N-dimethyl-4-nitrosoaniline (RNO) bleaching assay. The rate of RNO bleaching was seen to be retarded in the presence of DABCO, a specific 1O2 scavanger, providing evidence for the involvement of 1O2 as an active intermediate. The relative efficiencies of the generation of 1O2, with respect to immobilized rose bengal (PS-RB), by different polymer-supported porphyrins, were determined to be 0.29, 0.27, and 0.16 for PS-H2TPPS, PS-ZnTPPS, and PS-CdTPPS, respectively. Binding of porphyrins to a polymer has been found to decrease the efficiency of the 1O2 generation, which could be attributed to the structural deformation of the appended porphyrins. © 2003 Wiley Periodicals, Inc.