Multidentate Triazole Coordination Unlocks Color-Tunable Plasmonic Gold Nanoparticle Films to Achieve High Catalytic Performance.

Gold nanoparticles (AuNPs) have shown considerable promise in catalysis and optoelectronics; however, their inherent tendency to aggregate and their limited processability hinder practical applications. Herein, we present a systematic ligand-engineering strategy for tailoring the hierarchical assembly of AuNPs into functional hybrid films, employing four structurally related 1,2,4-triazole multidentate molecules of increasing coordination complexity under a unified solution compounding-vacuum filtration-thermal curing route. The results demonstrate that the type, number, and interplay of coordinating functional groups on the triazole scaffold govern the assembly architecture and interparticle plasmonic coupling, enabling a ligand-programmed color-tunable effect from wine-red through purple and blue to gray-brown. Among the series, the C2H6N6S -modified film-bearing thiol (-SH), amine (-NH2), and hydrazide (-NHNH2) groups on a single molecular scaffold-delivers the highest catalytic activity for 2-nitrophenol reduction, achieving complete conversion within 14 min and maintaining over 95% conversion after nine consecutive cycles. Combined XPS, XRD, and SEM analyses attribute this performance to the multidentate coordination of C2H6N6S, which simultaneously enables dense particle packing, favorable electronic modulation of the Au surface, and robust structural stability. This work establishes a structure-property framework linking ligand multifunctionality to thin-film performance, and provides a rational design principle for engineering AuNP-based hybrid materials with tailored.