A Minireview on Azobenzene-Linked Photoswitchable Catalytic Systems

Light-responsive switchable catalysis has grown immensely due to its varied applications across several fields of chemistry. This minireview primarily focuses on two categories of azobenzene-linked catalytic systems: photoswitching bases and photoswitchable organometallic complexes. These systems exhibited switchable catalytic properties in response to light stimuli. Photoisomerization of the azobenzene units modulates the reaction selectivity, rate, or yield of reactions based on changes observed in geometric orientation or electronic properties. A wide range of organic transformations, such as the Henry reaction, Friedel-Crafts alkylation, alkyne-azide cycloaddition, Michael addition, ring-closing metathesis, and many more have been compiled and documented. The photoswitching catalysts exhibited higher catalytic activity in one of the isomeric states, usually via improved electron donating property, preferred geometry, or stronger interactions with reactants. This review aims to enlighten the feasibility of photoswitchable catalysts for complex organic transformations. The selective activation of the catalytic system would enable precise control over its dynamics, making photoswitchable catalysts highly valuable for diverse applications.