Visible-light photocatalysis promoted by solid- and liquid-phase immobilized transition metal complexes in organic synthesis

[Display omitted] •Recovery and reuse of photocatalysts.•Immobilization of photoredox catalysts on solid support.•Conception of homogeneous reusable catalysts for visible light-driven organic reactions.•Positive effects of solid supports on photocatalytic reaction.•Continuous flow photoreactions in the presence of reusable photocatalysts. This review summarizes synthetic approaches to reusable photocatalytic systems based on visible light-active transition metal complexes with chelating ligands containing pyridyl residues such as 2,2′-bipyridines, 1,10-phenanthrolines, 2,2′:6′,2′′-terpyridines and related ligands. The use of these materials in organic synthesis is then discussed focusing on 1) most active systems exhibiting a synergy effect between photophysical properties of immobilized complexes and photoactive solid supports and 2) reusability of the developed catalytic system.