Meso-Carbazole substituted palladium porphyrins: Efficient catalysts for visible light induced oxidation of aldehydes

The A3B and A2B2 type porphyrins having N-butylcarbazole and p-cyanophenyl groups are synthesized and characterized. Their palladium complexes have also been prepared and utilized as catalysts for the photo-oxidation reactions of aromatic aldehydes in good yields. Pd(II)porphyrins displayed decent phosphorescence at a670 nm and were able to generate singlet oxygen upon light irradiation. The calculated singlet oxygen quantum yields for Pd(II)porphyrins were between 57% and 73%. The photo-catalytic application of Pd(II)porphyrins for aerobic oxidation of aromatic aldehydes is demonstrated.