Optically Active CdSe-Dot/CdS-Rod Nanocrystals with Induced Chirality and Circularly Polarized Luminescence

Abstract

Ligand-induced chirality in semiconductor nanocrystals (NCs) has attracted attention because of the tunable optical properties of the NCs. Induced circular dichroism (CD) has been observed in CdX (X = S, Se, Te) NCs and their hybrids, but circularly polarized luminescence (CPL) in these fluorescent nanomaterials has been seldom reported. Herein, we describe the successful preparation of l- and d-cysteine-capped CdSe-dot/CdS-rods (DRs) with tunable CD and CPL behaviors and a maximum anisotropic factor ( g) of 4.66 × 10. The observed CD and CPL activities are sensitive to the relative absorption ratio of the CdS shell to the CdSe core, suggesting that the anisotropic g-factors in both CD and CPL increase to some extent for a smaller shell-to-core absorption ratio. In addition, the molar ratio of chiral cysteine to the DRs is investigated. Instead of enhancing the chiral interactions between the chiral molecules and DRs, an excess of cysteine molecules in aqueous solution inhibits both the CD and CPL activities. Such chiral and emissive NCs provide an ideal platform for the rational design of semiconductor nanomaterials with chiroptical properties.

Multi‐Dimensional Quantum Nanostructures with Polarization Properties for Display Applications

“…He et al also described L-and D-cysteine-capped CdSe/CdS dot-in-rods with tunable CD and CPL signals and a maximum anisotropic factor of 4.66 × 10 À 4 (Figure 7c, 7d). [32] The observed CD and CPL effects were sensitive to the relative absorption ratio of the CdS shell to the CdSe core, suggesting that the anisotropic g-factors in both CD and CPL increased to some extent for a smaller shell-to-core absorption ratio.…”

Spectroscopy for model heterogeneous asymmetric catalysis

“…Different aspects of this phenomenon have been elucidated frequently in multiple excellent contributions for metallic [84][85][86][87][88][89][90][91][92][93][94][95][96][97][98] and semiconducting nanoparticles. [99][100][101][102][103][104][105][106][107][108][109] Ma and coworkers summarized most of the works related to chirality transfer in 2017 where they considered four types of chirality in nanoparticles and gave examples of each. 110 The four types are the following: (1) geometrical chirality of the inorganic core, (2) geometrical chirality of the inorganic surface (also called chiral footprint), (3) geometrical chirality of the protecting shell, and (4) chiral field effect.…”

Optically active quantum dots with induced circularly polarized luminescence in amphiphilic peptide dendron hydrogel

“…However, the assembled QDs obtain the chirality from the chiral nanober. Hence, based on previous studies, 23,35,36 there were two conjectures of the induced CPL in the cogels. First, one reason for the chirality of QDs is the chiral arrangement of QDs induced by self-assembled chiral networks.…”

“…It has been reported that CPL-active QDs can be obtained by modifying achiral QDs with chiral capping reagents. 35,36 However, to date, only chiral cysteine has been used as the capping reagent because of strong conjugating ability of the thiol group. The only example of CPL-active QDs fabricated without cysteine was achieved by loading quantum dots with a chiral cavity of a protein nanocage.…”