Redox-active ligands: Recent advances towards their incorporation into coordination polymers and metal-organic frameworks

Abstract

• Developments in coordination polymers (CPs) and metal–organic frameworks (MOFs). • Electroactive CPs and MOFs possess unique redox-state dependent properties. • An exploration of key redox-active ligands investigated in the past eight years. • Emerging redox-active ligands inspired by organic photovoltaic devices (OPVs). • CP and MOFs with applications in solar cells, photo switches and photoelectrocatalysis. Over the past three decades, the field of coordination polymers (CPs) and metal–organic frameworks (MOFs) has developed rapidly due to the potential applications of these materials in gas storage, separations, catalysis and switching. Introducing redox properties into CPs and MOFs to electrochemically modulate their properties for the development of solid state electronic devices has been an interesting strategy applied in recent years. Notably, a challenge within this area is the engineering of framework materials with desired redox properties targeted at a specific function. This review explores some of the key redox-active ligands that have been investigated within the previous eight years as redox-active components of solid state materials and examines a number of key strategies for their integration into CPs and MOFs. This review further highlights emergent redox-active ligands in the literature, which take inspiration from the rich field of organic electronics. While these ligands remain largely unexplored in the field of MOFs and CPs, they offer new opportunities for the improvement of solar cells, light induced photo switches, efficient photoelectrocatalysts and long range, rapid charge transfer in MOF materials.