Artificial Mn4-oxido complexes mimic the oxygen-evolving center in photosynthesis

The understanding of the structure-function relationship of the oxygen-evolving center （OEC）, a MnaCacluster, in photosystem I1 is impeded mainly due to the complexity of the protein environment and lack of rational chemical models as a reference. In this study, two novel Mna-oxido complexes have been synthesized and characterized, in which the peripheral ligands of the [Mn4] core are provided by eight μ2-carboxylate groups and two neutral terminal ligands （pyridine or isoquinoline）. This type of peripheral ligation is very similar to the Mn4Ca-oxide model complexes recently reported to mimic the OEC. The new Mn4-0xide complex can catalyze the oxygen-evoNing reaction in the presence of But00H as an oxidant. The structure and redox properties comparison of the Mn4-0xido and Mn4Ca-oxido complexes provide important clues to understanding the functional role of Ca in the OEC in natural photosynthesis, and develop more efficient artificial catalysts for the water-splitting reaction in the future.