Chromophore Synthesis and Functionalization of Au25 Nanoclusters
Gold nanoclusters (<2nm in size) exhibit interesting optical properties due to the role of quantum confinement in their electronic energy levels. Functionalization of these clusters with chromophores has already found application in the biomedical fields among others and thus synthesis of novel clusters with new properties is desirable. This project aimed to create several novel functionalizations of [Au25(PPh3)10(SC6)5Cl2 ]2+ nanorods and [Au25(SC6)18]− nanospheres with N-(2-mercaptoethyl)pyrene-1-carboxamide, N-(2-mercaptoethyl)anthracene-1- carboxamide, and mercaptoethylcoumarin343 carboxamide. Ligands were synthesized by a twostep synthetic route, with an acyl chloride serving as the intermediate between the carboxylic acid starting materials and the final thiolated amines. Pure products were not produced and therefore no pure, functionalized clusters were produced. Instead, UV-Visible and fluorescence analysis of different concentrations of prepared ligands with the nanoclusters was conducted in order to investigate possible formation of functionalized clusters and their optical properties. This investigation revealed that when the ligands and nanoclusters were combined, shifts in fluorescence and absorbance were observed with nanocluster-N-(2-mercaptoethyl)pyrene-1- carboxamide and nanocluster-N-(2-mercaptoethyl)anthracene-1-carboxamide systems. Such shifts were not observed in nanocluster-anthracene carboxylic acid and nanocluster-pyrene carboxylic acid systems.