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Updated: Feb 24, 2026

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal

Published on: October 31, 2019

2‑アミノ‑4

Lani Attiwell¹, Max T Hill^2,3, Jonathan D Sellars^2,3

¹School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.

Crystal growth & design

|February 23, 2026

Abstract:

The structures of 2-amino-4'-chlorobenzophenone and 2-amino-4'-bromobenzophenone, previously determined at room temperature in the space group Pna2₁, have been redetermined at low-temperature revealing two different reversible phase transitions. Additionally, high-pressure X-ray diffraction studies were conducted to allow for a comparison of the behavior of these structures in response to different external stimuli. Variable temperature analyses reveal that 2-amino-4'-bromobenzophenone transitions to the monoclinic space group Pa accompanied by a nonmerohedral twinning. The monoclinic phase exhibits approximate symmetry mimicking that of the supergroup Pna2₁ but with a metric symmetry that precludes true Pna2₁ symmetry. The structure of 2-amino-4'-chlorobenzophenone transitions to an incommensurately modulated phase upon cooling. The changes in the structure are attributed to slight conformational variations and a rearrangement of the hydrogen bonding networks in the structure in response to stimuli. The phase transition for 2-amino-4'-bromobenzophenone is classified as second order and a mechanism involving multiple coincident nucleation events is inferred from the conformational change and the incidence of twinning. The transformation of 2-amino-4'-chlorobenzophenone to an incommensurate phase is proposed to arise due to thermal contraction of the structure, which allows distinct competing hydrogen bonding networks between neighboring molecules to evolve.

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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

Published on: May 15, 2017

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

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Published on: June 7, 2018

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