Efficient Ir<sup>III</sup> Photosensitizer Incorporated\nin the Metal–Organic Framework with the Bis-lophine-bipyridine\nMotif for C(sp<sup>3</sup>)‑C/N–H Cross-Coupling Reactions

Photocatalytic technology offers a potential solution\nto energy\nand environmental issues. The performance of photocatalysts directly\naffects the efficiency of photocatalysis. Iridium­(III)-based catalysts\nhave garnered attention due to their unique electronic structure and\nhigh catalytic activity. However, most Ir<sup>III</sup> catalysts\nare homogeneous and face issues such as low stability and difficulty\nin recycling. The research on heterogeneous Ir<sup>III</sup> catalysts\nhas become a hot topic, aiming to improve their stability and recyclability.\nIn this study, we designed a tetracarboxylate ligand containing bipyridine\nmodified with a bilophthalene unit, constructed a Zr-based metal–organic\nframework (MOF) with a 2-fold interpenetrating structure, and introduced\n[Ir<sup>III</sup>(ppy)<sub>2</sub>]<sup>+</sup> units through postmodification\nto form Ir@Zr-MOF. The heterostructure enhanced the utilization of\nlight energy and photocatalytic efficiency. Apart from the electron\ntransfer pathway between the original zirconium clusters and the bis-lophine-bipyridine\nunit, comparative studies of theoretical models showed that the introduction\nof the [Ir<sup>III</sup>(ppy)<sub>2</sub>]<sup>+</sup> unit reduced\nthe energy level and enhanced the absorption of visible light in the\n500–550 nm range, corresponding to the charge transfer between\nthe modified bis-lophine-bipyridine and [Ir<sup>III</sup>(ppy)<sub>2</sub>]<sup>+</sup> unit. Ir@Zr-MOF, as a photocatalyst, can facilitate\nthe trifluoromethylation of coumarins and the oxidative dehydrogenative\ncoupling reaction of ethers with aryl hydrazones. The conversion yields\nof the related reactions can reach up to 95%. The mechanism presumes\nthat the generation of superoxide radicals and the corresponding holes\nproduced by Ir@Zr-MOF are crucial for the photocatalytic reaction.\nThe generation of superoxide radicals can be verified by ESR. The\nhost–guest interactions and hole effects of Ir@Zr-MOF with\nreaction substrates were also explored through theoretical simulations.\nThis work provides a strategy for the heterogenization of Ir<sup>III</sup> catalysts, offering insights for the preparation of photosensitizers\nand the enhancement of light energy utilization.