Chiral Gold Nanoparticles: Preparation, Size-Selection

and Chiroptical Properties

Thomas Bürgi

Laboratoire de Chimie Physique des Surfaces, Neuchâtel, Switzerland

Attempts are described that aim at bestowing chirality onto metal nanoparticles. The latter can be viewed as the nanometer size analogues of extended metal surfaces. The solubility of these particles allows the application of chiroptical techniques such as circular dichroism (CD) and vibrational circular dichroism (VCD), i.e. the differential absorption of left- and right-circularly polarized light. The latter technique yields, in combination with quantum chemical calculations, information on the structure of the adsorbed molecules. The former technique probes electronic transitions that might be located in the metal core. Gold nanoparticles covered by chiral thiols that were separated into well-defined compounds by gel electrophoresis show circular dichroism in metal-based electronic transitions. Possible origins for this observation are discussed.