Immobilization of a Full Photosystem in the Large-Pore MIL-101 Metal-Organic Framework for CO2 reduction

A molecular catalyst [Cp*Rh(4,4-bpydc)](2+) and a molecular photosensitizer [Ru(bpy)(2)(4,4-bpydc)](2+) (bpydc=bipyridinedicarboxylic acid) were co-immobilized into the highly porous metal-organic framework MIL-101-NH2(Al) upon easy postsynthetic impregnation. The Rh-Ru@MIL-101-NH2 composite allows the reduction of CO2 under visible light, while exhibiting remarkable selectivity with the exclusive production of formate. This Rh-Ru@MIL-101-NH2 solid represents the first example of MOFs functionalized with both a catalyst and a photosensitizer in a noncovalent fashion. Thanks to the coconfinement of the catalyst and photosensitizer into the cavity's nanospace, the MOF pores are used as nanoreactors and enable molecular catalysis in a heterogeneous manner.