Photoactivation of Molecular Oxygen by an Iron(III) Porphyrin with a Magnesium Aluminum Layered Double Hydroxide for the Aerobic Epoxidation of Cyclohexene

The photocatalytic aerobic epoxidation of cyclohexene proceeded under visible‐light irradiation only if 5,10,15,20tetrakis(pentafluorophenyl)porphyrin iron(III) chloride ([Fe III (TPFPP)Cl]) was combined with Mg‐Al layered double hydroxide (Mg‐Al LDH) as a solid base in chloroform. The OH groups in the Mg‐Al LDH exchanged with the axial Cl ligands in [Fe III (TPFPP)Cl] to afford [Fe III (TPFPP)OH], which functioned photocatalytically in the presence of Mg‐Al LDH but was inactive in its absence. The band in the action spectrum agreed well with the Soret band in the UV/Vis absorption spectrum of [Fe III (TPFPP)OH]. The spectral changes indicated the reduction of [Fe III (TPFPP)OH] to [Fe II (TPFPP)] under visible‐light irradiation, which in turn activates O 2 that could be used for the epoxidation of cyclohexene.