Multiresponsive Luminescent Behaviors of Assembled Spirocyclic Nonanuclear Silver(I) Clusters

Abstract

Supramolecular assembly is regarded as an effective strategy to endow metal clusters with rich and unique photophysical properties. However, the detailed mechanisms and influential factors for intercluster assemblies and their effects on luminescent properties remain unclear to date. In this work, we constructed a series of spirocyclic nonanuclear silver cluster compounds with varying alkyl chain lengths, which demonstrated distinct supramolecular assembly behaviors depending on temperature, concentration, and solvent polarity. We observed significant changes in the morphology of their assemblies from irregular particles to nanofibers during the aggregation process. The assembly of spirocyclic silver clusters not only generated emission enhancement but also gave rise to intriguing alkyl length-related mechano- and vapochromic luminescent properties. X-ray crystallographic analysis illustrated that the alkyl chain-dependent intramolecular and intermolecular π-π stacking, together with hydrophobic interactions, accounted for the distinguished assembly and optical properties. This study offers insight into the objective law of cluster assemblies and provides a viable avenue for the development of novel cluster-based stimuli-responsive materials.