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Updated: May 26, 2026

Magnetic Tweezers for the Measurement of Twist and Torque
Published on: May 19, 2014
Macroscopic torsional strain and induced molecular conformational deracemization
Rajratan Basu1, Joel S Pendery, Rolfe G Petschek
1Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Abstract:
A macroscopic helical twist is imposed on an achiral nematic liquid crystal by controlling the azimuthal alignment directions at the two substrates. On application of an electric field the director rotates in the substrate plane. This electroclinic effect, which requires the presence of chirality, is strongest at the two substrates and increases with increasing imposed twist distortion. We present a simple model involving a trade-off among bulk elastic energy, surface anchoring energy, and deracemization entropy that suggests the large equilibrium director rotation induces a deracemization of chiral conformations in the molecules-effectively "top-down" chiral induction-quantitatively consistent with experiment.
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