近日，荷兰埃因霍温理工大学Paul van der Schoot团队研究了液晶中的手性放大和手性偏析。该项研究成果发表在2026年3月3日出版的《美国科学院院刊》杂志上。
非手性分子的液晶中介相通常是非手性的，但在少数材料中，它们会自发分离形成左手性和右手性的手性畴。驱动这种手性分离的机制之一是轴向手性构象之间的分子形状涨落，在此过程中分子间相互作用倾向于匹配手性并促进螺旋扭转。协同手性有序也可能在手性放大中发挥作用，例如当极少量的手性掺杂剂驱动向列相转变为胆甾相时。
研究组利用迈耶-绍普理论提出了一个液晶中协同手性有序的模型，并预测了一个相图，其中除了外消旋向列相和各向同性相之外，还存在一个分离的胆甾相，该相具有左手性和右手性螺旋扭转交替出现的畴，且对映体过量相反。该模型还演示了手性分子涨落如何影响掺杂剂在向列相中的螺旋扭曲力，即使在那些分离胆甾相被其他相变所取代的材料中，这种效应也可能被观测到。
研究组将这些结果与可切换手性勒沃-拉舍尔模型的蒙特卡罗模型研究进行了比较，在该模型中每个自旋在左手性和右手性手性态之间切换。模拟结果验证了预测的相图，展示了外消旋向列相中的手性放大现象，并揭示了分离胆甾相中复杂的粗化动力学。这些结果表明，简并手性构象之间的分子涨落可能是非手性液晶中产生协同手性有序的一种普遍机制。
附：英文原文
Title: Chirality amplification and chiral segregation in liquid crystals
Author: Deutsch, Matthew J., Selinger, Robin L. B., van der Schoot, Paul
Issue&Volume: 2026-3-3
Abstract: Liquid crystal mesophases of achiral molecules are normally achiral, yet in a few materials they spontaneously segregate and form right- and left-handed chiral domains. One mechanism that drives chiral segregation is molecular shape fluctuations between axial chiral conformations, where molecular interactions favor matching chirality and promote helical twist. Cooperative chiral ordering may also play a role in chirality amplification, as when a tiny fraction of chiral dopant drives a nematic phase to become cholesteric. We present a model of cooperative chiral ordering in liquid crystals using Maier-Saupe theory, and predict a phase diagram with a segregated cholesteric phase with alternating domains of left- and right-handed chiral twist, with opposite enantiomeric excess, in addition to racemic nematic and isotropic phases. Our model also demonstrates how chiral molecular fluctuations influence the helical twisting power of dopants in the nematic phase, which may be observed even in materials where the segregated cholesteric phase is preempted by a transition to another phase. We compare these results with Monte Carlo simulation studies of the switchable chiral Lebwohl-Lasher model, where each spin switches between right- and left-handed chiral states. Simulation results validate the predicted phase diagram, demonstrate chiral amplification in the racemic nematic phase, and reveal complex coarsening dynamics in the segregated cholesteric phase. These results suggest that molecular fluctuations between degenerate chiral configurations may be a common mechanism to produce cooperative chiral order in achiral liquid crystals.
DOI: 10.1073/pnas.2514297123
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2514297123