Spectral and flash kinetic studies of water-soluble zinc porphyrins in poly-N-vinyl-2-pyrrolidone matrix

✍ Scribed by Bidyut Kr. Manna; Dipankar Sen; Subhash Ch. Bera; K.K. Rohatgi-Mukherjee

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 1000 KB
• Volume: 48
• Category: Article
• ISSN: 1386-1425
• DOI: 10.1016/0584-8539(92)80239-s

✦ Synopsis

Abatraet-A series of water-soluble zinc porphyrins, ZnTPPS, ZnTPPC and ZnTPPOH, have been synthesized. Their absorption, emission, singlet and triplet state quenching by electron acceptors like MVZf and 1,5-AQDS*-have been studied in homogeneous aqueous solutions and bound to a PVP matrix. Binding constants for the systems under study do not vary much and give a low value for AC'=-13.37 kJM-'. However, the number of monomer units required for binding any individual porphyrin species varies with the size of the molecule. It appears that these water-soluble porphyrins are embedded in hydrophobic pockets in the polymer matrix and are only partially available to outside quenchers like MV'+ and 1,5-AQDS*-From flash photolysis studies, formation of porphyrin radical cations and quencher anions is observed. Porphyrin cations are long-lived and are also formed on self-quenching and by disproportionation reactions in the absence of quencher. ZnTPPOH behaves differently.