Engineering Synergistic Di-Iron Sites and Anion Microenvironments in a Metal-Organic Framework Catalyst for Aerobic Wacker-Type Olefin Oxidation

Abstract

The deliberate construction of cooperative multinuclear metal sites within heterogeneous catalysts offers a promising strategy for enhancing catalytic performance, yet precise control over metal-metal synergy and local anion environments remains challenging. Here, we demonstrate a programmable metal-organic framework (MOF) platform in which flexible pyridylmethylamine (pyma) side chains are grafted onto a UiO-67 framework and coordinated with iron salts bearing different counteranions, enabling the construction of di-iron centres with tuneable anion environments. The resulting MOF-confined di-iron catalyst efficiently promotes the aerobic Wacker-type oxidation of a wide range of olefins under mild conditions, exhibiting broad substrate scope and good functional-group tolerance. Comparative studies with mononuclear analogues and catalysts bearing different counteranions (Cl⁻, Br⁻, OAc⁻, OTf⁻) reveal that both metal-metal cooperation and the local anion environment govern catalytic performance. This work thus establishes a design principle for engineering adaptive multinuclear catalysts with tunable microenvironments in confined spaces to achieve advanced oxidation reactions.