Molecular Packing-Driven\nManipulation of Aggregation\nInduced Emission in Gold Nanoclusters

A key limitation of supramolecular force-driven molecular\nassembly\nin aggregation-induced emission (AIE) materials is the need to precisely\nregulate molecular interactions within the assembly. Achieving such\nassemblies with in situ manipulable molecular arrangements could provide\nvaluable insights into the role of molecular forces in AIE. Herein,\nby using glutathione-protected gold nanoclusters (AuNCs) as a model\nAIE material and a naturally occurring polyphenol, tannic acid (TA),\nas the assembling agent, we demonstrate that assemblies dominated\nby covalent bonds and hydrogen bonding show enhanced AIE, while those\ndominated by π–π stacking promote charge transfer,\nresulting in significant photoluminescence (PL) quenching. This phenomenon\nprimarily stems from the oxidation of TA into smaller aromatic ring\nstructures, leading to an increase in π–π interactions.\nThe complete in situ oxidation of TA within the assembly induces a\nmorphological transition from 3-D spherical to 2-D sheet-like structures\ndue to the dominance of π–π interactions, consequently\nresulting in complete PL quenching of AuNCs. These findings highlight\nthe critical role of molecular packing in modulating the AIE properties\nof AuNCs.