Given the rising socioeconomic issues of fossil fuels, efficient artificial photosynthesis would be an important milestone toward a sustainable world. A key step of photosynthesis is the catalytic photooxidation of water by photosystem II, which has a mean lifetime of 30 min under full sunlight. Since the efficiency of photosystem II is controlled by redox-active tyrosine–histidine pairs that regulate the light-induced flow of charges, research has recently focused on the utilization of redox-active ligands in artificial systems. Here we review the molecular catalysis of water oxidation with emphasis on redox cooperation modes between ligands and metal centers. Molecular systems involving redox-active ligands could achieve up to 100% efficiency with respect to oxygen production, overpotential of 200–300 mV and turnover frequency above 100 s⁻¹, which is comparable to the natural process. Nonetheless, molecular catalysts are often prone to degradation of the organic ligand. The oxidative activation of ligands can contribute to the water oxidation reactivity of a metal–ligand complex, or lead to controlled catalyst film formation. We discuss the design of functional analogs to the tyrosine–histidine pair that for the most part rely on abundant elements and exploit redox-active molecular moieties to assist the catalytic centers. We highlight analogies with the cooperation between the natural oxygen-evolving complex and the redox-active tyrosine–histidine pairs found in photosystem II.

鉴于化石燃料日益严重的社会经济问题，高效的人工光合作用将成为迈向可持续世界的重要里程碑。光合作用的一个关键步骤是光系统 II 对水的催化光氧化，在充足的阳光下其平均寿命为 30 分钟。由于光系统 II 的效率由调节光诱导电荷流动的氧化还原活性酪氨酸-组氨酸对控制，因此研究最近集中在人工系统中氧化还原活性配体的利用上。在这里，我们回顾了水氧化的分子催化，重点是配体和金属中心之间的氧化还原合作模式。涉及氧化还原活性配体的分子系统可以实现高达 100% 的氧气生产效率、200-300 mV 的过电位和 100 秒以上的转换频率^-1，这与自然过程相当。尽管如此，分子催化剂通常易于降解有机配体。配体的氧化活化有助于金属-配体配合物的水氧化反应，或导致受控的催化剂膜形成。我们讨论了酪氨酸-组氨酸对的功能类似物的设计，其大部分依赖于丰富的元素并利用氧化还原活性分子部分来辅助催化中心。我们强调了与在光系统 II 中发现的天然放氧复合物和氧化还原活性酪氨酸-组氨酸对之间的合作的类比。