Synthesis and photophysical behaviour of tantalum and titanium phthalocyanines in the presence of gold nanoparticles: Photocatalysis towards the oxidation of cyclohexene

We report on the synthesis of 2,(3)- (peripheral) and 1,(4)- (non-peripheral) (2-mercaptopyridine)phthalocyanine complexes of titanium (IV) oxide (5 and 6 respectively), and tantalum (III) hydroxide (7, peripheral only), their photochemical and photophysical parameters and the photocatalytic oxidation of cyclohexene in the presence of gold nanoparticles (AuNPs). The singlet oxygen quantum yield values increased in the presence of AuNPs, for complexes 5 and 6. The percentage conversion values for cyclohexene using 5, 6 and 7 were 27%, 20% and 14%, respectively. These values increased considerably in the presence of AuNPs, except complex for 7. The products obtained include cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,2-cyclohexanediol. Low values of singlet oxygen quantum yields favour the formation of 1,2-cyclohexanediol.

► Tantalum and titanium (mercaptopyridine)phthalocyanine are synthesized.
► Tantalum phthalocyanine shows low singlet oxygen yield.
► All complexes photocatalyse the transformation of cyclohexene.
► The products include the oxide, alcohol and ketone.