Mechanistic insights from atomically precise gold nanocluster-catalyzed reduction of 4-nitrophenol

A trio of thiolate-protected atomically precise gold nanoclusters, [Au-23(S-c-C6H11)(16)](-), Au-24(SCH(2)pH(t)Bu)(20) and [Au-25(SCH(2)CH(2)pH)(18)](-), are utilized as catalysts for 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP). Despite nearly identical sizes (similar to 1 nm), the three nanoclusters possess distinctly different atomic packing structures and surface ligand binding modes, which contribute to different catalytic performance. The [Au-23(S-c- C6H11)(16)](-) nanocluster shows the highest activity with a kinetic rate constant of 0.0370 s(-1), which is higher than those of Au-24(SCH(2)pHtBu)(20) (0.0090 s(-1)) and [Au-25(SCH(2)CH(2)pH)(18)](-) (0.0242 s(-1)). Such a trio of gold nanoclusters indicate that the atomic packing mode and electronic structure play a crucial role in determining their catalytic performance.