pH-guided self-assembly of silver nanoclusters with aggregation-induced emission for rewritable fluorescent platform and white light emitting diode application.

Metal nanoclusters (NCs) as a new type of fluorescent material have attracted great interest due to their unique electronic structure and outstanding optical properties. However, limited success has been achieved in the preparation of water-soluble NCs with high luminous intensity. In this article, the significant luminescence properties of 4-mercaptobenzoic acid (Hmba)-capped Ag NCs induced by hydrochloric acid (HCl) through self-assembly strategies were reported and the water-soluble protonated silver nanoclusters (Ag-H-NCs) can be obtained. The original non-luminescent Ag NCs exhibit stable and bright luminescence resulting from aggregation-induced emission (AIE) by forming an ordered nanorod structure after assembly. Optical analysis allows for the establishment of relationships between ordered alignment and emission of Ag NCs components and it can be concluded that the ordered nanostructures are constructed by non-covalent interaction (hydrogen bond, π-π stacking, etc.) which effectively inhibits the intramolecular vibration and rotation of the ligand, thereby increasing the emission intensity of Ag NCs. Due to the outstanding optical behavior of the aqueous solution of Ag-H-NCs, it can be used as a rewritable fluorescent platform and a white light emitting diode (LED). The pH-guided strategy enriches the supramolecular self-assembly of novel noble metal NCs, which makes them a good candidate for optical materials.