Effects of shape and solute-solvent compatibility on the efficacy of chirality transfer: Nanoshapes in nematics

Abstract

Chirality, as a concept, is well understood at most length scales. However, quantitative models predicting the efficacy of the transmission of chirality across length scales are lacking. We propose here a modus operandi for a chiral nanoshape solute in an achiral nematic liquid crystal host showing that that chirality transfer may be understood by unusually simple geometric considerations. This mechanism is based on the product of a pseudoscalar chirality indicator and of a geometric shape compatibility factor based on the two-dimensional isoperimetric quotients for each nanoshape solute. The model is tested on an experimental set of precisely engineered gold nanoshapes. These libraries of calculated and in-parallel acquired experimental data among related nanoshapes pave the way for predictive calculations of chirality transfer in nanoscale, macromolecular, and biological systems, from designing chiral discriminators and enantioselective catalysts to developing chiral metamaterials and understanding nature’s innate ability to transfer homochirality across length scales.

The significance of nanoparticle shape in chirality transfer to a surrounding nematic liquid crystal reporter medium

“…Moreover, reflecting on our appreciation that an independently calculated hG a oa i can predict experimental trends of |b mol |, we put this system to the test with a significant expansion of the scope of our research by focusing on more pronounced shape and AR variations. 26 This was ultimately accomplished by comparing calculations of a shape-corrected hG a oa i, described next, with the experimental values gathered for |b mol | for a larger set of gold nanoshapes now including nanoprisms (GNPR), nanodisks (GND), nanostars (GNS) as well as GNRs differing in AR. All gold nanoshapes were monolayer-capped with the identical cholesterol-thiol ligand shell shown in Fig.…”

“…8a); for S XN we now introduced a shape-complementarity model to quantify the shape resemblance (or shape incongruity) between the N-LC molecule serving as host and the chiral ligand surface-modified nanoshape. 26 The use of |G a oa,max | was justified by the fact that the HTP data were calculated from experimental pitch measurements, which are particularly sensitive to the highest rather than average chirality values (particularly for a system containing various contributions of different chirality).…”

“…Moreover, reflecting on our appreciation that an independently calculated 〈 G a oa 〉 can predict experimental trends of | β mol |, we put this system to the test with a significant expansion of the scope of our research by focusing on more pronounced shape and AR variations. 26…”

“…8a); for S XN we now introduced a shape-complementarity model to quantify the shape resemblance (or shape incongruity) between the N-LC molecule serving as host and the chiral ligand surface-modified nanoshape. 26…”

Azobenzene-decorated cellulose nanocrystals as photo-switchable chiral solutes in nematic liquid crystals

“…The underlying mechanism is based on the scalar product of an established pseudoscalar chirality indicator and a scalar geometric shape compatibility factor based on the 2-D isoperimetric ratio of the nanoshape solute and the used N-LC molecules. 1,10…”