University of Oulu

Ahola, S., Ingman, P., Laatikainen, R., Sinkkonen, J., Jokisaari, J. (2018) 21Ne and 131Xe NMR study of electric field gradients and multinuclear NMR study of the composition of a ferroelectric liquid crystal. Journal of Chemical Physics, 149 (23), 234901. doi:10.1063/1.5052499

²¹Ne and ¹³¹Xe NMR study of electric field gradients and multinuclear NMR study of the composition of a ferroelectric liquid crystal

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Author: Ahola, Susanna K.1; Ingman, Petri1,2; Laatikainen, Reino3;
Organizations: 1NMR Research Unit, University of Oulu
2Instrument Centre, Department of Chemistry, University of Turku
3Department of Pharmacy, University of Eastern Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 0.4 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe201901041301
Language: English
Published: American Institute of Physics, 2018
Publish Date: 2019-01-04
Description:

Abstract

This study has two goals. First, the electric field gradient (EFG) present in the liquid-crystalline phases of ferroelectric FELIX-R&D is determined using NMR spectroscopy of noble gases ²¹Ne and ¹³¹Xe. The ²¹Ne and ¹³¹Xe NMR spectra were recorded over a temperature range, which covers all the mesophases of FELIX-R&D: nematic N*, smectic A, and smectic C*. The spin quantum number of both ²¹Ne and ¹³¹Xe is 3/2. Their electric quadrupole moment interacts with the EFG at the nuclear site, which in liquid-crystalline phases results in the NMR spectra of the triplet structure, instead of a singlet detectable in the isotropic phase. The total EFG experienced by the noble gas nuclei consists of two contributions; one arises from the quadrupole moments of the liquid crystal molecules (external contribution) and the other one from the deformation of the electron distribution of the atoms (deformational contribution). The total EFGs determined from the ¹³¹Xe and ²¹Ne quadrupole splittings are very similar in the nematic and smectic A phases but differ in the smectic C* phase, being about twice larger in the ²¹Ne case which stems from the larger deformation of the xenon electron cloud than that of neon. For the first time, EFG was determined also in the smectic C* phase applying noble gas NMR spectroscopy. Second, the structure of molecules which, as a mixture, compose the used ferroelectric liquid crystal, FELIX-R&D, is determined by applying a number of various NMR methods and sophisticated spectral analysis. In this part, NMR spectra were recorded from FELIX-R&D/CDCl3 solution. The NMR spectral analysis was divided into four subsystems with over 13 000 000 nonzero intensity transitions. It appeared that FELIX-R&D is composed of three phenyl pyrimidine derivatives and a chiral dopant with fluorine in the asymmetric carbon atom,

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Series: Journal of chemical physics
ISSN: 0021-9606
ISSN-E: 1089-7690
ISSN-L: 0021-9606
Volume: 149
Issue: 23
Article number: 234901
DOI: 10.1063/1.5052499
OADOI: https://oadoi.org/10.1063/1.5052499
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Subjects:
Copyright information: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The article "Ahola, S., Ingman, P., Laatikainen, R., Sinkkonen, J., Jokisaari, J. (2018) 21Ne and 131Xe NMR study of electric field gradients and multinuclear NMR study of the composition of a ferroelectric liquid crystal" appeared in Journal of Chemical Physics, 149 (23), 234901, and may be found at https://doi.org/10.1063/1.5052499.