Kinetically Controlled Structural Modulation of the Self-Assembled Silver Nanoclusters

Metal nanoclusters (NCs) with atomic precision are growing into a fascinating class of building blocks for supramolecular chemistry. What makes it more interesting is the enhanced optical properties of the ordered structures, including aggregation-induced emission (AIE). However, algorithm dictating the self-assembly of metal NCs in multicomponent environment remains largely unknown, and effective means to manipulate the self-assembly is still lacking, especially under kinetic control. Herein, nanofibers which contain sub-1 nm nanowires and exhibit circularly polarized phosphorescence (CPP) are obtained from crystallization-induced self-assembly (CISA) of water-soluble, negatively charged silver NCs (Ag9-NCs) in the presence of glutamic acid (Glu). By the introduction of a positively-charged additive (choline chloride, CC), the structure of the nanowires is modulated and the lateral interaction between adjacent nanofibers is adjusted, leading to simultaneous improvement of the phosphorescence and chirality which finally enhances CPP. Importantly, changing the time at which CC is introduced altered the kinetic pathway of the CISA, which enables to effectively manipulate both the final structures of the self-assembled Ag9-NCs and the output of the optical signals. Crystallization-induced self-assembly (CISA) of water-soluble silver nanoclusters with atomic precision (Ag9-NCs) is induced by chiral organic molecule of glutamic acid, leading to the formation of phosphorescent, chiral nanofibers composed of sub-1 nm nanowires. Introduction of choline chloride retards the CISA and alters the kinetic pathway, which modulates the structure and improves the circularly polarized phosphorescence of the self-assemblies.image