A Raman study on the intracluster interactions of aminothiophenol‐protected Ag₇ clusters—Photo‐assisted N─N coupling reaction of the ligand

Abstract

We have synthesized Ag 7 nanoclusters via a facile one-pot procedure with p-aminothiophenol (PATP) as the ligand. The chemical component of this Ag 7 cluster is determined to be Ag 7 (C 6 H 6 NS) 7 H + by high-resolution electrospray mass spectrometry, where a few fragment peaks are also observed such as [Ag 7 (C 6 H 6 NS) 4 H 3 Na] + . For this PATP-protected Ag 7 cluster, we have conducted a Raman investigation to probe in the intracluster interactions and find an essentially different Raman feature from that the nascent PATP ligand, pertaining to photo-assistant catalytic conversion of PATP to p,p'-dimercapto azobenzene (DMAB). Utilizing density-functional-theory (DFT) calculations, we have performed natural population analysis, natural bond orbital analysis, and electron density difference analysis to fully demonstrate the intracluster interactions between Ag 7 clusters and the ligand. What is interesting is that the protection ligand PATP helps stabilize the Ag 7 metallic core, and in turn, the metal core Ag 7 catalyzes the protection ligands giving rise to N─N coupling reaction. On this basis, we have proposed a reaction pathway on a basis of DFT calculations to provide further insights into the reaction mechanism of PATP-to-DMAB conversion at the presence of the Ag 7 clusters.