Chiral nanoparticle assemblies: circular dichroism, plasmonic interactions, and exciton effects

The paper reviews recent progress on chiral nanocrystal assemblies with induced optical chirality and related circular dichroism. Many natural molecules and biomolecules are chiral and exhibit remarkably strong optical chirality (circular dichroism) due to their amazingly uniform atomic composition in a large ensemble. It is challenging to realize artificial nanoscale systems with optical chirality since the atomic structure of artificial nanostructures may not be always controlled or even known. Nevertheless, the artificial optical chirality has been accomplished and it is the main scope of this review. In particular, we discuss assemblies incorporating chiral molecules, metal nanocrystals, and semiconductor quantum dots. Plasmon-induced and plasmon-enhanced circular dichroism effects appear in nanoscale assemblies built with metal nanocrystals, while excitonic and surface-states related phenomena are observed in semiconductor quantum dots conjugated with chiral molecules.