Solvation-mediated isomerization of surface motifs tunes emissions and electron transfer dynamics in gold nanoclusters

Metal nanoclusters (NCs) are attracting increasing attention for their molecule-like photoluminescence (PL) properties, while achieving emission tuning remains a challenge. Here, we report the solvation-triggered isomerization of surface terminations and modulation of electron transfer dynamics in the 6-mercaptopurine-9-β-D-ribofuranoside (6-MPR)-protected gold NCs, to attain a controllable emission spanning widely from 495 nm sky-blue to 800 nm near-infrared light. Specifically, the isomerization of 6-MPR gives Au(I)-thione isomer terminals (i.e., R1 domain) and Au(I)-thiol isomer terminals (i.e., R2 domain), confers the gold NCs with two prominent emission bands at 590 nm (i.e., PL I from the electron transfer emission state) and 770 nm (i.e., PL II from the triplet state), respectively. The further solvation of gold NCs is rationally designed by mapping out fourteen different organic solvents into four categories referring to their inherent properties of viscosity, polarity, coordination ability, and the strength of proton-giving capacity. This allows for rational conversion between R1 and R2 domains, and is concurrent with modulation of the proton-coupled electron transfer dynamics and thus customizable emission tuning. Tuning the emission of metal nanoclusters is a challenge. Here, the authors report on solvation-induced isomerization and modulation of electron transfer dynamics to achieve controllable emission across the entire visible range.