Indolocarbazole-Based Photosensitizers: A New Synthetic Motif for Constructing Metal–Organic Framework toward Selective Photocatalytic Oxidation

Metal–organic frameworks (MOFs) have become widely used as functional materials for a wide range of applications, including heterogeneous photocatalytic oxidation reactions, due to their high porosity, unique structures, and inherent physicochemical properties. In the photocatalytic system, the core of constructing photoactive MOFs lies in choosing suitable monomers to achieve selective oxidation with high efficiency. In this paper, a metal–organic framework NUT-99 that was constructed from indolo[3,2- b ]carbazole (ICZ) derivative ligands was synthesized and used as an efficient heterogeneous photocatalyst. NUT-99 demonstrates good photocatalytic performance toward the selective oxidation of sulfides to sulfoxides under 420 nm blue light irradiation in ambient air, achieving >98% conversion and selectivity. Mechanistic investigations reveal that the selective oxidation of sulfides proceeds via the ICZ structure, which stimulates the production of singlet oxygen, leading to catalytic oxidation via an energy-transfer pathway. The present study highlights the potential of molecules bearing ICZ structures to design and synthesize photocatalytic porous materials.