Efficient and Monochromatic Electrochemiluminescence of Aqueous-Soluble Au Nanoclusters via Host-Guest Recognition

Inspired by the enhanced photoluminescence of Au nanoclusters (AuNCs) with a rigid shell, the formation of rigid host-guest assemblies on AuNC surfaces was employed to screen novel electrochemiluminophores with 6-aza-2-thiothymine(ATT)-protected AuNCs (ATT-AuNCs) and l-arginine (ARG) as models for the first time. The rigid host-guest assemblies formed between ARG and ATT on the ATT-AuNC surface enabled aqueous-soluble ARG/ATT-AuNCs with a dramatically enhanced electrochemiluminescence (ECL) compared to ATT-AuNCs. This includes one cathodic ECL process (-1.30 V) and three anodic ECL processes (+0.78, 0.90, and 1.05 V) in a so-called half-scan experiment without a co-reactant, as well as a 70-fold enhanced oxidative-reduction ECL at +0.78 V with tri-n-propylamine as a co-reactant. Importantly, the ECL of the ARG/ATT-AuNCs is highly monochromatic with an emission maximum around 532 nm and a full width at half-maximum of 36 nm, which is of great interest for color-selective ECL assays.