Chiral Amplification by L‐Cysteine‐Capped Gold Nanoparticles in Lyotropic Chromonic Liquid Crystals

Abstract

Transfer of chirality from an adsorbed molecule to a metal nanoparticle surface, and from the resulting chiral nanoparticle to its surroundings, depends on numerous factors – structure of the adsorbed molecule, its size and shape, and its interactions with its specific environment – but is often difficult to understand and even more difficult to measure, visualize, and quantify. This severely limits the potential of chiral nanoparticles in a range of emerging applications as optical metamaterials, enantioselective catalysts, or chiral discriminators for biomacromolecules. We examine if chirality at the nanoscale (i. e. in gold nanoparticles capped with chiral ligand molecules) is uniquely able to generate more intense responses than their organic chiral counterparts in soft condensed matter utilizing lyotropic chromonic liquid crystals (LCLCs) forming the nematic phase. As a powerful manifestation of nanoscale chiral amplification, we show that L‐cysteine capped gold nanoparticles induce a tighter chiral twist within, and similar among, stacks of nematic LCLCs with several orders of magnitude fewer chiral L‐cysteine ligands in comparison to the free molecular L‐amino acid.

Amplification of Chirality by Adenosine Monophosphate-Capped Luminescent Gold Nanoclusters in Nematic Lyotropic Chromonic Liquid Crystal Tactoids

“…The ICD spectra shown in Figure 4 are characterized by broad bands centered around 340 nm that appear to be from two overlapping bands at 310 and 350 nm, observed in the UV–vis spectrum of the N-phase formed by DSCG in water 24 similar to ICD spectra reported earlier for induced lyotropic N*-LCLC phases of DSCG in water. 24…”

“…We determined that Θ was about five orders of magnitude more intense for the l -cysteine-capped AuNPs with an overall l - cysteine concentration of 10 –4 wt % in comparison to the sample of DSCG in water doped with 12 wt % neat l -cysteine. 24…”

Chirality amplification by desymmetrization of chiral ligand-capped nanoparticles to nanorods quantified in soft condensed matter

“…Thin films for ICD spectropolarimetry were prepared between two quartz substrates separated by ~ 10-μm Kapton tape spacers. Samples were rotated in 45° intervals from 0° to 315° (in the plane normal to the light beam) in order to differentiate CD absorption (reflection) from linear dichroism and birefringence as described elsewhere in more detail 53 .…”

Anisotropic Fast Electrically Switchable Emission from Composites of CsPbBr3 Perovskite Quantum Cuboids in a Nematic Liquid Crystal

“…Recalling that the efficiency of the LEDs is lower in the green/yellow spectral range, the system investigated here may be attractive. Nano‐soft composites comprising LCs as host and nanostructures as the guest is an emerging area of research that gets benefitted by the unique characters of the latter in the self‐assembling features of LCs . A variety of nanoparticles have been employed to alter/tune the LC properties.…”