Azobenzene-based photoswitchable catalysts: State of the art and perspectives

• Azobenzene-based photoswitchable catalysts are classified. • Mechanisms of photoswitchable catalytic activity are described. • Strategies to enable photoswitchable catalysis are presented. • Challenges and perspectives of azobenzene-based photoswitchable catalysts are discussed. Photoswitchable catalysts are becoming attractive materials for catalytic applications because of their favorable characteristics, such as customizable catalytic activity and particularly possible recyclability, as well as the unique advantages of light stimulation, such as low cost, good harvesting, non-toxicity and excellent stability. In this mini-review article, we focus primarily on azobenzene-based photoswitchable catalysts, in which the active sites are integrated with azobenzene. Single molecules, molecular assemblies, molecularly printed polymers and organometallics are systematically classified according to the type of active sites. The scientific challenges and the remaining opportunities are emphasized to demonstrate the future prospects of azobenzene-based photoswitchable catalysts. This mini-review article is expected to provide comparative perspectives and critical insights to promote more in-depth research on photoswitchable catalysts and to expand the feasibility of photoswitchable catalysis.