Pd(II) porphyrins: Synthesis, singlet oxygen generation and photoassisted oxidation of aldehydes to carboxilic acids

The synthesis and spectral studies of A<inf>3</inf>B and A<inf>2</inf>B<inf>2</inf> type porphyrins and their Pd(II) complexes are reported. The meso-positions on porphyrin macrocycle are substituted with pentafluorophenyl and N-butylcarbazole or triphenylamine groups. Pd(II) porphyrins displayed decent phosphorescence ∼670 nm and are able to produce singlet oxygen by type II pathway, after photoirradiation. The calculated singlet oxygen quantum yields for Pd(II) porphyrins are (Φ<inf>Δ</inf> = 30%–63%). The catalytic application of Pd(II) porphyrins towards photoassisted aerobic oxidation of aromatic aldehydes to carboxylic acids is demonstrated.