Room-temperature photoluminescence in monocarboxylate-protected silver nanoclusters via steric hindrance-induced interfacial structure locking

Tuning the optical properties of monolayer-protected nanoclusters through manipulation of their interfacial structures constitutes a compelling research direction. Herein, we report two atomically precise monocarboxylate-protected superatomic silver nanoclusters (RCO₂-AgNCs), formulated as {Ag₁₆(RCO₂)₁₂[(4-ClPh)₃P]₈}²⁺ [where R = 2,4,6-trimethylphenyl (2,4,6-Me₃Ph) for Ma or 9-anthracenyl (9-An) for Mb], which features similar chemical composition, identical inner core while distinct interfacial coordination structures. When the RCO₂-AgNCs undergoes a transition from an unlocked periphery ligand shell to a locked one, it evolves from exhibiting no luminescent properties at room temperature to possessing such properties. Photoluminescence and femtosecond transient absorption spectroscopies demonstrate that remarkable emission property of Ma is ascribed to the highly efficient energy transfer process occurring between phosphine ligand and metallic kernel, in conjunction with the suppression of molecular vibration imposed by the locked shell. This study not only elucidates the correlations between interfacial structure and photoluminescence properties of RCO₂-AgNCs but also provides insights for designing nano-optical devices with atomic precision.