Spectroscopic and electrochemical studies on oxaporphyrins and oxathiaporphyrins

The synthesis and characterization of oxaporphyrins (OTPP and O2TPP) contai ning one and two furan rings in place of pyrrole and a mixed oxathiaporphyr in (OSTPP) is reported. Spectroscopic and electrochemical studies reveal th at oxaporphyrins exhibit optical and emission characteristics closer to the parent H2TPP, while their electrochemical behaviour parallels that reporte d for mono and dithiaporphyrins. However the characteristics of the mixed o xathia derivative resemble that of monothiaporphyrin. Protonation studies r eveal weaker resonance interaction between the beta-hydrogens and meso-phen yl substituents in sharp contrast to thiaporphyrins. The reduction potentia ls for OSTPP and O2TPP indicate stabilization and destabilization of their LUMOs relative to the parent H2TPP in the ground and excited states, respec tively. (C) 1998 John Wiley & Sons, Ltd.