Co-assembly of Ag₂₉ Nanoclusters with Ru(bpy)₃²⁺ for Two-Photon Up-Conversion and Singlet Oxygen Generation

Cluster ensembles by supramolecular interactions are expected to be a class of promising materials possessing interesting properties and attractive features. We herein present a new functional and atomically precise supramolecular silver nanocluster, Na[Ru(bpy)3][Ag29(BDT)12(TPP)2] (Ag29Ru), by coassembling the star cluster Na3[Ag29(BDT)12(TPP)4] (Ag29) with the classic photosensitizer Ru(bpy)3Cl2. Taking advantage of electrostatic interactions and intermolecular hydrogen bonding, Ru(bpy)32+ was constrained by the void spaces of the lattice of [Ag29(BDT)12(TPP)2]3– clusters, which reduced the symmetry of the original structure of [Ag29(BDT)12(TPP)4]3– with the shedding of TPP. Interestingly, Ag29Ru exhibits a prominent difference in the singlet oxygen generation under visible light irradiation compared to results for pure Ag29. DFT calculations show that the greater singlet oxygen production capacity is driven by the narrowed HOMO–LUMO gap of the Ag29Ru coassembly of Ag29 with Ru(bpy)32+. More interestingly, the resulting Ag29Ru exhibits a typical two-photon excited photoluminescence, which opens a new avenue to obtain metal cluster-assembled functional materials.