Executive Summary : | Metal nanoclusters (NC) with particle diameters less than 2 nm have recently attracted significant attention mainly because their photoluminescence (PL) properties, which makes them highly relevant for imaging applications e.g. in biology and medicine. But one of the major problem is their low PL quantum yield (QY) compared to semiconductor quantum dots of organic dyes. In order enhance their PLQY, many open questions such as the role of ligands, origin of their PL needs fundamental understanding and careful consideration. The current results on the origin of this PL are still highly diverse. Up to now, it is impossible to clearly correlate their PL properties with their ligand’s architecture. This is because of the scarce of systematic experimental reports on understanding the ligand’s role in their PL properties. This project aims to synthesize organic ligand-free metal NCs (especially Ag and Cu) and understand the ligands’ architecture’s role by employing a series of ligand addition and studying their effect on the PL properties. The project also aims to expand this study on atomically precise organic ligand-protected Ag and Cu NCs by employing ligand exchange and conjugation strategies. This systematic ligand variation will be done by changing the anchor groups (e.g. thiol, amine, phosphine), the nature of ligand charge (i.e. by changing the tail groups, such as carboxyl and amines) as well as their distance from the NC surface via spacer molecules of different lengths (e.g. carbon chain lengths). The data acquired during this research project will be combined in order to develop a unified theory on the origin of PL in metal NCs. This understanding will help in tuning the PL quantum yield (QY) of metal NCs which are beneficial for PL-based applications especially in bio-imaging. |