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

Chang, Wenyan, Chen, Changhui, Dong, Hongxing, Zhang, Chunxi
Science bulletin 2017
calcium, catalysts, catalytic activity, ligands, manganese oxides, models, oxidants, oxygen, photosystem II, pyridines, quinoline, structure-activity relationships
The understanding of the structure-function relationship of the oxygen-evolving center (OEC), a Mn4Ca-cluster, in photosystem II 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 Mn4-oxido complexes have been synthesized and characterized, in which the peripheral ligands of the [MnIII4] 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-oxide complex can catalyze the oxygen-evolving reaction in the presence of ButOOH as an oxidant. The structure and redox properties comparison of the Mn4-oxido 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.