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Synthesis of 4-Chloro-1,3-Diazobenzene Bent-Cores Liquid Crystal and Characterizations of Its Mesogenic Behaviors and Photosensitivity

preprint
revised on 09.05.2020, 00:26 and posted on 11.05.2020, 10:15 by Jinying Lu, Zelong Zhang, Daoren Yan, Zhiyong Zhang, Jintao Guan, Junfei Qiao

Azobenzene-based bent-core liquid crystals demonstrate a variety of mesomorphic behaviours and photochromic properties which are desirable for optical switching. In this study, a novel compound 4c was synthesised by adding azo functional groups and chlorine substituent to the central bent-core. The structure, mesogenic properties, and photosensitivity of 4c was characterised by fourier-transform infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance (NMR), mass spectrometry (MS), differential scanning calorimetry (DSC), polarised optical microscopy (POM), and ultraviolet–visible spectroscopy (UV-Vis). The experimental results show that 4c exhibited a broad temperature window of nematic phase (63.8 °C), rapid trans – cis photoisomerisation in seconds, and high cis fraction of 0.81. At room temperature, 4c dissolved in ethyl acetate can reach photostationary state in 10 seconds. At 95 °C, nematic 4c became isotropic under UV irradiation in 3 seconds and can be restored to be nematic under natural visible light in 5 seconds. Quantum mechanics calculations confirm that using azos instead of esters as the central linkages can effectively reduce the molecular dipole moment and enhance the overall molecular polarisabilities, which promotes favourable mesogenic and photonic behaviours. This study provides novel synthesis route and synergistic approach to advance the design of azobenzene bent-core liquid crystals.

Funding

Microscopic mechanism of banana-shaped liquid crystal electro-optic effect and kinetics

National Natural Science Foundation of China

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Study on Nonlinear Periodic Structure and Transport Model of Curved Liquid Crystals Induced by Light Field

National Natural Science Foundation of China

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XSEDE 2.0: Integrating, Enabling and Enhancing National Cyberinfrastructure with Expanding Community Involvement

Directorate for Computer & Information Science & Engineering

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Directorate for Computer & Information Science & Engineering

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History

Email Address of Submitting Author

zelongz@lsu.edu

Institution

Louisiana State University

Country

United States

ORCID For Submitting Author

0000-0002-0807-8991

Declaration of Conflict of Interest

No potential conflict of interest was reported by the authors.

Version Notes

Preprint (submitted copy to Liquid Crystals)

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