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Issue 8, 2016
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A combined experimental and theoretical approach to study SmC → NcybC phase transition in a four-ring bent-core liquid crystal

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Abstract

A newly synthesized four-ring bent-core liquid crystal (BCLC) has been studied using experimental and quantum chemical approach. Differential scanning calorimetry (DSC), polarised optical microscopy (POM), and X-ray investigations were carried out to identify the phase transitions and associated phases. DSC along with POM revealed four phase transitions i.e. Cr → SmX → SmC → NcybC → Iso in the temperature range from 30 °C to 180 °C. The existence of smectic C like fluctuations also known as cybotactic groups in the broad temperature range of the nematic phase was confirmed by small angle X-ray diffraction. Conformational and vibrational analyses have been performed using density functional theory (DFT), to identify the most stable conformer having a bent shape. Analysis of the potential energy surface (PES) for different torsional angles revealed the most probable conformational states for the BCLC. Temperature dependent Fourier transform infrared (TD-FTIR) spectroscopy is used to study phase transitions and revealed marked changes in the spectral line shape especially the vibrations of OH, CH2, CH3, C[double bond, length as m-dash]O, and HC[double bond, length as m-dash]N groups during the SmC → NcybC phase transition above ∼95 °C. A good agreement between the calculated and observed infrared spectra validates the structure of this conformer that has been used for further studies.

Graphical abstract: A combined experimental and theoretical approach to study SmC → NcybC phase transition in a four-ring bent-core liquid crystal

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Supplementary files

Article information


Submitted
19 Mar 2016
Accepted
30 May 2016
First published
31 May 2016

New J. Chem., 2016,40, 6834-6847
Article type
Paper

A combined experimental and theoretical approach to study SmC → NcybC phase transition in a four-ring bent-core liquid crystal

S. Singh, R. Deb, N. Chakraborty, H. Singh, V. Gupta, K. Sinha, P. Tandon, M. Omelchenko, N. V. S. Rao and A. P. Ayala, New J. Chem., 2016, 40, 6834
DOI: 10.1039/C6NJ00892E

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