Molecular Conformations of Shape Anisometrically Variant Mesogens in Liquid Crystalline Phase Studied by 13C NMR Spectroscopy

Veeraprakash, B and Shanavas, AKJ and Reddy, GSM and Lobo, NP and Ramanathan, KV and Narasimhaswamy, T (2023) Molecular Conformations of Shape Anisometrically Variant Mesogens in Liquid Crystalline Phase Studied by 13C NMR Spectroscopy. In: ChemPhysChem, 24 (23).

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Abstract

Mesogens that vary in shape anisometry have been investigated by 13C solid-state NMR in the liquid crystalline phase to inspect the conformations. The molecules examined comprise of (i) rod-like mesogen with three-phenyl ring core and terminal hexyloxy chains, (ii) three-ring core linked to the fourth phenyl ring via a spacer, and (iii) trimesic acid connected to three side arms core units through a spacer. The order parameter (Szz) values for the phenyl rings of the rod-like mesogen are 0.65–0.68, while the mesogen with a three-ring core linked to a phenyl ring via spacer showed dissimilarity. Consequently, for the core unit phenyl rings, Szz is ~0.70, and the terminal phenyl ring showed a low value of 0.12. For the trimesic acid based mesogen, the Szz value for the side arm phenyl rings is ~0.53, and for the central phenyl ring, a very low value of 0.11 is witnessed. By considering the ordering of the rod-like mesogen as a yardstick and employing the ratios of Szz values of the phenyl rings, the average conformations of other mesogens are arrived. Accordingly, for the trimesic acid based mesogen, a tripod-like conformation instead of λ shape is proposed in the liquid crystalline phase. © 2023 Wiley-VCH GmbH.

Item Type:	Journal Article
Publication:	ChemPhysChem
Publisher:	John Wiley and Sons Inc
Additional Information:	The copyright for this article belongs to the John Wiley and Sons Inc.
Keywords:	Liquid crystals; Nuclear magnetic resonance spectroscopy, 13C NMR; Dipolar couplings; Liquid-crystalline phasis; Liquid-crystals; Mesogens; Molecular conformation; Molecular shapes; Phenyl rings; Ring-core; Trimesic acid, Conformations
Department/Centre:	Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility)
Date Deposited:	18 Dec 2023 03:06
Last Modified:	18 Dec 2023 03:06
URI:	https://eprints.iisc.ac.in/id/eprint/83477

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