A disulfur ligand stabilization approach to construct a silver(i)-cluster-based porous framework as a sensitive SERS substrate.

An atomically-precise silver(i)-cluster-based three-dimensional (3D) framework (UJN-1) stabilized by a ditiocarb (diethyldithiocarbamate) ligand has been unveiled for the first time by self-assembly. UJN-1 is composed of both Ag9 clusters and Ag5 subunits, of which the Ag9 clusters are bonded with Ag5 subunits by sharing the ditiocarb ligand to form a microporous 3,4-connected topological framework. The chemically reduced nano-sized derivative of UJN-1 exhibits highly sensitive surface enhanced Raman scattering (SERS) towards 4-mercaptobenzoic acid (4-MBA) signal molecules, which is ascribed to the porosity as well as the distribution of abundant crystalline Ag0 active sites. This work sheds light on a new bottom-up approach to construct SERS-active silver(i)-cluster-based 3D materials by disulfur ligand stabilization.