Silver in the Center Enhances Room-Temperature Phosphorescence of a Platinum Sub-nanocluster by 18 Times.

There has been controversy surrounding the roles of the metal core (metal-metal interaction) and the shell (metal-ligand interaction) in photoluminescence of ligand-protected metal nanoclusters. We have discovered aggregation-induced room-temperature phosphorescence of a platinum-thiolate complex and its silver ion inclusion complex (a silver-doped platinum sub-nanocluster). The inclusion of silver ion boosted the photoluminescent quantum yield by 18 times. Photophysical measurements indicate that the rate of nonradiative decay was slower for the silver-doped platinum sub-nanocluster. DFT calculations showed that the LUMO, which had the main contribution from Ag s-orbital and Pt d-orbitals, played a critical role in suppressing the structural distortion at the excited state. This work will hopefully stimulate more research on designing strategies based on molecular orbitals of atomicity-precise luminescent multimetallic nanoclusters.