Role of Ligand on Photophysical Properties of Nanoclusters with fcc Kernel: A Case Study of Ag14(SC6H4X)12(PPh3)8 (X = F, Cl, Br)

The structure-property correlation of a series of silver nanoclusters (NCs) is essential to understand the origin of photophysical properties. Here, we report a series of face-centered cubic (fcc)-based silver NCs by varying the halogen atom in the thiolate ligand to investigate the influence of the halide atoms on the electronic structure. These are {Ag-14(FBT)(12)(PPh3)(8)center dot(solvent)(x)} (NC-1), Ag-14(CBT)(12)(PPh3)(8) (NC-2), and Ag-14(BBT)(12)(PPh3)(8) (NC-3), where 4-fluorothiophenol (FBT), 4-chlorothiophenol (CBT), and 4-bromothiophenol (BBT) have been utilized as thiolate ligands, respectively. Interestingly, the optical and electrochemical bandgap values of these NCs nicely correlated with the electronic effect of the halides, which is governed by the intracluster and interclusters pi-pi interactions. These clusters are emissive at room temperature and the luminescence intensity increases with the lowering of temperature. The short lifetime data suggest that the emission is predominantly originating due to the interband relaxation (d -> sp) of the Ag cores. Femtosecond transient absorption (TA) spectra revealed similar types of decay profiles for NC-2 and NC-3 and longer decay time for NC-2. The relaxation dominates the decay profile to the surface states and most of the excited-state energy dissipates via this process. This supports the molecular-like dynamics of these series of NCs with an fcc core. This overview shed light on an in-depth understanding of ligand's role in luminescence and transient absorption spectra.

Automated summary

The structure-property correlation of a series of silver nanoclusters reveals a strong relationship between the optical and electrochemical bandgap values and the electronic effect of halides, governed by intracluster and intercluster pi-pi interactions. Emission from these clusters at room temperature is predominantly due to interband relaxation of the Ag cores, with femtosecond transient absorption spectra showing decay profiles dominated by relaxation to surface states. This sheds light on the molecular-like dynamics of these nanoclusters with a face-centered cubic core.