Abstract

Inspired by natural photosynthesis, there is a vision that fuels and chemicals can be synthesized using Earth’s basic elements (i.e., H2O , CO2, N2) and removable energy. This concept has given rise to the multidisciplinary field of artificial photosynthesis.2-4 One of the most appealing research areas in this context is the mechanistic understanding of multi-electron, multi-proton processes central to transforming small molecules in artificial photosynthesis. These studies have provided new insights into the processes and led to the discovery of new reactivity. In this regard, we will discuss a procedure for synthesizing water oxidation catalysts and an ideal reaction to extract reductive equivalents. On the reductive side, we have discovered well-defined coordination complexes that are highly efficient homogeneous catalysts for reducing water,1, and CO22 and organic substrates such as ketones, aldehydes, and olefins.3 The low valent metal intermediates also promote the challenging visible-light reductive radical C-C bond formations from unactivated chloroalkanes, which opens new avenues in photoredox catalysis.4 We will also discuss how to control the selectivity between water reduction and the reduction of organic functionalities. Finally, mechanistic understanding unlocks the reactivity of the Ir-based photosensitizers