Chiral silver nanoclusters to enhance sensing
Small metal clusters possess many unique optical properties that can be exploited in applications such as chemical sensing, catalysis and light harvesting. Size, ligand and chemical environment have all been shown to play critical roles in the absorption and emission quality of silver nanoclusters. Within the NPINMUPSS (Separation of nanoparticles (NP) in multiphase systems (MuPSs)) project, scientists used a mix of ligands in the proximity of silver, bestowing it chirality that should further enhance its optical properties. Using a binary ligand system consisting of L-cysteine (L-cys) and mercaptohexanoic acid (MHA), the team reported formation of chiral silver nanoclusters. In particular, formation of nanoclusters was linked to the presence of the achiral ligand, MHA, whereas chirality was attributed to the presence of L-Cys. Independently of the ligand ratio or the silver-to-thiol ratio, the team observed the formation of chiral nanoclusters of similar chemistry. Using circular different spectroscopy techniques (circular dichroism and ultraviolet-visible), they also characterised the cluster optical properties. Project work suggested that only by mixing chiral and achiral ligands one can impart chirality in silver nanostructures. Use of an achiral ligand can influence the ordering of a ligand shell and thereby introduce chirality to silver nanoclusters. NPINMUPSS resulted in four publications as well as two patent applications.
