Ligand-induced chirality and optical activity in semiconductor nanocrystals: theory and applications

Abstract

Chirality is one of the most fascinating occurrences in the natural world and plays a crucial role in chemistry, biochemistry, pharmacology, and medicine. Chirality has also been envisaged to play an important role in nanotechnology and particularly in nanophotonics, therefore, chiral and chiroptical active nanoparticles (NPs) have attracted a lot of interest over recent years. Optical activity can be induced in NPs in several different ways, including via the direct interaction of achiral NPs with a chiral molecule. This results in circular dichroism (CD) in the region of the intrinsic absorption of the NPs. This interaction in turn affects the optical properties of the chiral molecule. Recently, studies of induced chirality in quantum dots (QDs) has deserved special attention and this phenomenon has been explored in detail in a number of important papers. In this article, we review these important recent advances in the preparation and formation of chiral molecule–QD systems and analyze the mechanisms of induced chirality, the factors influencing CD spectra shape and the intensity of the CD, as well as the effect of QDs on chiral molecules. We also consider potential applications of these types of chiroptical QDs including sensing, bioimaging, enantioselective synthesis, circularly polarized light emitters, and spintronic devices. Finally, we highlight the problems and possibilities that can arise in research areas concerning the interaction of QDs with chiral molecules and that a mutual influence approach must be taken into account particularly in areas, such as photonics, cell imaging, pharmacology, nanomedicine and nanotoxicology.

Endowing inorganic nanomaterials with circularly polarized luminescence

“…Ligand-induced chirality in inorganic nanomaterials with CPL property has the potential to be applied in chiral biosensors, enantioselective synthesis, and chiroptical devices due to their excellent physicochemical properties, such as chemical stability, surface functionality, and adjustable quantum confinement effects. [52,53] Chiroptical response in CPL spectra can be originated from chiral interactions between chiral capping reagent and achiral core, ligand-induced chiral defects or surfaces. In the terms of chiral interactions, orbital coupling and Coulombic interaction are regarded as the dominating mechanisms for chirality transfer.…”

Engineering of inorganic nanostructures with hierarchy of chiral geometries at multiple scales

“…Several extensive reviews on chiral inorganic nanoparticles (NPs) and their assemblies were published over the last few years that described, in various degrees of detail, the chiral nanostructures known today 17–30 . Along with their preparation and optical properties, these works also discuss their potential applications which include but not limited to chiral catalysis, enantiospecific separation, biosensing, chiral memory, and chiroptical devices.…”

Competitive induction of circularly polarized luminescence of CdSe/ZnS quantum dots in a nucleotide–amino acid hydrogel

“…2,9 On the other hand, chirality is a basic property in biological systems, thus the development of chiral inorganic materials, such as quantum dots, Au nanoparticles and clusters is a pressing issue in research into the biological system. [10][11][12][13][14] Many works have been reported so far for the fabrication of chiral QDs, which generally showed circular dichroism (CD) [15][16][17][18][19] . However, QDs with circularly polarized luminescence (CPL) emission are rarely explored.…”