Binuclear Mn(III) and Fe(III) porphyrin nanostructured materials in catalytic reduction of 4-nitrophenol

Biomimetic reduction reactions may disclose alternatives to the use of noble metals or transition metals of late series that are expensive, toxic, or scarcer. In this work, binary nanostructured materials carrying positive and negative iron (III) and manganese (III) porphyrins were prepared by ionic self-assembly, in a simple and eco-sustainable way, and characterized by SEM, XRD, UV–vis and XPS. The materials were evaluated as catalysts in the reduction of 4-nitrophenol in water, using NaBH4 as a reductant. The effect of the crystallite structures, of the nature of the dual metal ion centers and of solar light, in the catalyst activity were also evaluated. The highest activity was observed for a heterobimetallic [Mn/Fe] material carrying Fe(III) and Mn(III) porphyrins as positive and negative tectons, respectively, leading to complete conversion of the 4-nitrophenol in 3 min under simulated solar light, and the results evidence a synergy between the two metal centers. This material was reused in successive catalytic cycles until the 7th cycle.