A novel porphyrinic photosensitizer based on the molecular complex of meso-tetraphenylporphyrin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone: higher photocatalytic activity, photooxidative stability and solubility in non-chlorinated solvents

摘要: In order to overcome problems associated with the use of porphyrins under photooxidative conditions, 1 : 2 molecular complex meso-tetraphenylporphyrin (H2TPP) 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been used as a photosensitizer for aerobic photooxidation olefins. Under optimized H2TPP(DDQ)2 showed significantly increased catalytic activity and oxidative stability compared that free base porphyrin. Interestingly, 1H NMR UV-vis studies DDQ molecules efficiently prevent protonation H2TPP acidic condition formed by exposure chlorinated solvents light. The photosensitizing ability adduct was found be mainly dependent on light absorption in Soret band region much lesser extent Q(0,0) region. Furthermore, substantially solubility acetonitrile facilitated safer solvent than common reactions. Also, influence different parameters including type power source, molar ratio olefin efficiency catalyst quantum yield photochemical reaction (Φ) investigated. 1,3-diphenylisobenzofuran quencher singlet oxygen 1,4-benzoquinone scavenger superoxide anion radical revealed involvement major reactive species.