Synergistic Multiple Bonds Induced Dynamic Self-Assembly of Silver Nanoclusters into Lamellar Frameworks with Tailored Luminescence

Abstract

Incorporating atomically precise metal nanoclusters (NCs) into ordered self-assemblies endows them with advanced photophysical properties; however, their ordered arrangement in space is difficult to achieve with only noncovalent bonds between individual clusters. Herein, we illustrate the hierarchical self-assembly of atomically precise silver NCs (NH4)6[Ag6(mna)6] (Ag6-NCs) into hexagonal two-dimensional lamellas by intercluster π···π and C-H···π interactions, which then pack into three-dimensional metal–organic frameworks (MOFs) by the metal–ligand coordination interaction. Synergistic multiple bond-induced dynamic coassembly greatly enhanced the quantum yields and lifetimes, achieving the transformation of weak fluorescence to strong thermally activated delayed fluorescence (TADF). The structure and luminescence transformation could be reversibly switched by tuning the pH values. The Ag6-NCs/Ca2+ coassemblies behaved as efficient yellow phosphors to afford white light emitting diode devices. This work demonstrates a synergistic multiple bond-induced hierarchical self-assembly to realize ordered layer-by-layer MOFs from NCs-based secondary building units with advanced TADF emission in a pH-tailored manner for potential applications in luminescent devices and sensors.