Active molecular units in metal organic frameworks for artificial photosynthesis

Metal organic frameworks (MOFs) are polymeric solid-state coordination compounds that can link photoactive and catalytically active molecular entities and maintain their activity and mechanism within their 3D structure, resembling the large photosynthetic apparatus in natural photosynthesis. This review categorizes photocatalytically active MOFs according to their structural properties and the location of the photosensitizer (PS) and catalyst (CAT) in the following types with respect to the linker and secondary building unit (SBU): (I) the PS and CAT are represented or localized at the linker and SBU, respectively, (II) the PS and CAT are represented or localized by/at different linkers, (III) the PS and CAT are both bound to the SBU, (IV) the PS and CAT are bound to the linker or SBU but as a PS-CAT dyad, and (V) the PS and/or CAT are assembled non-covalently within MOF pores. Furthermore, all reported studies on artificial photosynthesis are summarized in the context of light-driven H₂ evolution, CO₂ reduction, overall water splitting, water oxidation and other oxidations such as alcohol and amine oxidation, which are relevant in the field of artificial photosynthesis. Additionally, this review presents an overview on the stability and repair strategies for these MOFs.