Au(SePh) nanomolecules: Synthesis, optical spectroscopy and theoretical analysis

Here, we report the synthesis of selenophenol (HSePh) protected Au(SePh) nanomolecules via a ligand-exchange reaction of 4-tert-butylbenzenethiol (HSPh-tBu) protected Au(SPh-tBu) with selenophenol, and its spectroscopic and theoretical analysis. Matrix assisted laser desorption ionization (MALDI) mass spectrometry, electrospray ionization (ESI) mass spectrometry and optical characterization confirm that the composition of the as synthesized product is predominantly Au(SePh) nanomolecules. Size exclusion chromatography (SEC) was employed to isolate the Au(SePh) and temperature dependent optical absorption studies and theoretical analysis were performed. Theoretically, an Independent Component Maps of Oscillator Strength (ICM-OS) analysis of simulated spectra shows that the enhancement in absorption intensity in Au(SePh) with respect to Au(SPh) can be ascribed to the absence of interference and/or increased long-range coupling between interband metal core and ligand excitations. This work demonstrates and helps to understand the effect of Au-Se bridging on the properties of gold nanomolecules.