Regulation of aggregation-induced emission properties of Ag(0)@Ag(I) rich-thiolate core-shell nanoclusters: Ligand assembly dominated.

ABSTRACT

Aggregation-induced emission (AIE) is an effective strategy for improving the photoluminescence (PL) performance of metal nanoclusters (MNCs). However, the origin of AIE in MNCs is still not fully understood, which is pivotal for the design of AIE luminogens (AIEgens). Here, water soluble silver nanoclusters (Ag NCs) with AIE properties were synthesized. These as-synthesized non-luminescent Ag NCs will become photoluminescent when transferred from water to ethanol, and the emission peak was redshifted from ∼560 to ∼600 nm and largely intensified with the addition of Cu2+. The addition of Cu2+ makes a big difference in the PL properties of Ag NCs. That is, the PL will be enhanced if Cu2+ is added with the sequence "Ag NCs + Cu2++EtOH." In contrast, the PL will be quenched if Cu2+ is added with the sequence "Ag NCs + EtOH + Cu2+." The PL was from the supramolecular clusters formed by the assembly of capping ligands on the confined surface of individual silver clusters through weak interactions. The addition of Cu2+ could regulate the assembly structure and further affect the energy lever (p-band) through space electron interactions. These results provide new insights into the AIE process in metal nanoclusters.