Fast, high-yield synthesis of amphiphilic Ag nanoclusters and the sensing of Hg2+ in environmental samples

We report the high-yield (74%) synthesis of Ag-30(Capt)(18) (abbreviated as Ag-30) in a very time-saving fashion (half an hour). The cluster composition was determined by high-resolution mass spectrometry combined with TG analysis, and the structure was probed by 1D and 2D NMR. Interestingly, the nano-clusters can dissolve in water and methanol, as well as in most organic solvents such as ethanol, acetone, acetonitrile, dichloromethane and ethyl acetate with the assistance of acetic acid. Such a good solubility in a range of various polar solvents was not reported previously in nanoclusters' research and is important for applications. An important result from this work is that Ag-30 can sense a low concentration of Hg2+ in environmental samples (including lake water and soil solution), indicating that Ag-30 can be a potential colorimetric probe for Hg2+. The sensing mechanism was revealed to be related to the anti-galvanic reduction process.