A Cerium-Naphthazarin Catecholate MOF as a Heterogeneous Photocatalyst for Selective Functionalization of Alkanes

Abstract

In this work, we have successfully synthesized a series of novel semiconducting 2D catecholate metal-organic frameworks (MOFs) based on naphthazarin ligands by utilizing unraveled metal-acetyl acetonate linkage chemistry. The synthesized MOFs exhibited excellent light absorption properties and chemical stability across various solvents. Its insoluble and stable framework, combined with an optimal band gap, enabled its use as a photocatalyst for organic transformations. For the first time, Ce-Naph MOF is explored as a heterogeneous catalyst for photocatalytic applications specifically for the selective C–H amination of alkanes, achieving yields of up to 89% under ambient conditions. We propose that the initial metal-to-ligand charge transfer in Ce-Naph MOF, promoted by light, is essential for forming an active alkoxy-Ce(IV)-species. This species subsequently undergoes ligand-to-metal charge transfer to generate the alkoxy radical, which acts as a hydrogen atom transfer reagent to activate alkanes. Furthermore, Ce-Naph MOF demonstrated long-term cyclic stability, maintaining its catalytic activity and structural integrity over five cycles, highlighting its durability as a heterogeneous catalyst. We are confident that this straightforward and practical methodology opens new avenues for industrial applications, significantly advancing the fields of metal catalysis, photocatalysis, and sustainable chemistry.