Synthesis of an Oxo-Bridged Fe(III) Porphyrin(2.1.2.1) Dimer and Its Enhanced Electrocatalytic Oxygen Evolution

A Fe(III) porphyrin(2.1.2.1) oxo-bridged dimer complex was synthesized using porphyrin(2.1.2.1) as a bent ligand. The resulting complex adopts an oxo-bridged and cross-stacked molecular structure. DFT calculations reveal antiferromagnetic coupling between the two iron centers, characterized by an exchange coupling constant of J = -129.5 cm^-1. TDDFT simulations reproduce the key features of the experimental UV-vis spectrum, indicating that the brightest transitions correspond to a predominantly LMCT (π → d) character. The electrocatalytic OER study and DFT-based mechanistic analysis demonstrate that the bridging oxo ligand plays an important role in enhancing catalytic activity, with a lower overpotential for the rate-determining step.