Dipole-induced ordering in nematic liquid crystals. II. The elusive holy grail

Syvitski, Raymond T.; Burnell, E. Elliott

doi:10.1063/1.1287336

Cited by 30 publications

(28 citation statements)

References 42 publications

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“…Similar findings were obtained for a collection of aromatic solutes dissolved in ZLI 1132, EBBA and a magic mixture of these component liquid crystals. 47 Therefore, the present experiments on ethane and its isotopomers lend additional support to the notion that average external electric field gradients are important in these liquid crystals.…”

Section: Ethane Dipolar Couplingssupporting

confidence: 75%

Molecules with Large-Amplitude Torsional Motion Partially Oriented in a Nematic Liquid Crystal: Ethane and Isotopomers

et al. 2005

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An NMR study on ethane and five isotopomers dissolved in the nematic liquid crystal Merck ZLI 1132 is performed. A consistent set of dipolar and quadrupolar couplings is obtained. The dipolar couplings are corrected for harmonic vibrational effects, while the contribution from the torsional motion is incorporated classically. The corrected dipolar couplings cannot be understood in terms of a reasonable molecular structure unless effects of the reorientation-vibration interaction are taken into account. Assuming that the reorientationvibration contributions that are known for the methyl group in methyl fluoride are transferable to ethane, excellent agreement between observed and calculated dipolar couplings is obtained on the basis of the ethane gas-phase structure. The observed and calculated deuterium quadrupolar couplings show discrepancies supporting the notion that average electric field gradients are important in liquid-crystal solvents. An important consequence of the transferability of the reorientation-vibration correlation is that in other molecules with a methyl group the same procedure as for ethane can be followed. Inclusion of this effect generally removes the need to interpret changes in observed dipolar couplings in terms of elusive chemical effects.

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Section: Ethane Dipolar Couplingssupporting

confidence: 75%

Molecules with Large-Amplitude Torsional Motion Partially Oriented in a Nematic Liquid Crystal: Ethane and Isotopomers

et al. 2005

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“…27 These results, together with the nonintuitive sign found for S xx − S yy in the present study, indicate that the mean-field approximation ͑in conjunction with the efg-Q mol interaction͒ is not sufficient for rationalizing the finer details of the orientational ordering in liquid crystals other than in the MM.…”

Section: Discussionmentioning

confidence: 50%

“…However, there is a problem: the signs of the efg in 1132 and in EBBA are opposite to those found in the deuterium experiments as well as in the study of mono-and di-substituted benzenes. 27 The "wrong" sign obtained for F ZZ in 1132 and EBBA can be predicted from Fig. 4 where it is noted that S xx − S yy changes sign between 1132 and EBBA, with a positive slope for dct and a negative one for cxl.…”

Section: Resultsmentioning

confidence: 87%

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Orientational order of near D3h solutes in nematic liquid crystals

Danilovič

Burnell

2009

The Journal of Chemical Physics

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Solutes that are similar in size, have a shape that is close to D(3h) symmetry but contain dissimilar substituent groups (methyl versus chloro, contributing different electrostatic interactions to the anisotropic intermolecular potential), are used to delineate the short- and long-range anisotropic intermolecular interactions that lead to solute orientational order in nematic liquid crystals. The short-range interactions should be similar for all solutes and for D(3h) symmetry should yield a single independent order parameter, whereas the long-range interactions are expected to differ with solute. Short-range size and shape mechanisms account for solute orientational order measured in magic mixtures (e.g., 55 wt % ZLI-1132/N-p-ethoxybenzylidene-p(')-n-butylaniline), whereas additional mechanisms are required in other nematic liquid-crystal solvents. The results obtained for long-range interactions cannot be rationalized in detail using simple mean-field models that incorporate solute dipoles, quadrupoles, or polarizabilities. The results suggest that details of the solute electrostatics may need to be incorporated into the description of the anisotropic intermolecular potential.

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“…In some studies more than one solute per sample has been utilized. 6,7 The idea is that all solutes in the same sample should be directly comparable. However, the total solute concentration in such cases can be considerable, and the solute environment may differ significantly from that experienced in a dilute sample.…”

Section: Introductionmentioning

confidence: 99%

Effects of solute properties and concentrations on liquid crystals: N-(4-ethoxybenzylidene)-2,6-dideutero-4-n-butylaniline

Syvitski

Pau

Burnell

2002

The Journal of Chemical Physics

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Articles you may be interested inEffect of lithium on the properties of a liquid crystal formed by sodium dodecylsulphate and decanol in aqueous solution J. Chem. Phys. 139, 014703 (2013); 10.1063/1.4811678 Obtaining the structure and bond rotational potential of a substituted ethane by NMR spectroscopy of solutions in nematic liquid-crystalline solvents Quantum-mechanical studies of NMR properties of solutes in liquid crystals: A new strategy to determine orientational order parameters Orientational and interaction induced dynamics in the isotropic phase of a liquid crystal: Polarization resolved ultrafast optical Kerr effect spectroscopyThe effects of the nature and concentration of the solutes 1,3,5-trichlorobenzene ͑TCB͒, benzene, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, and p-dichlorobenzene on orientational order in the nematic liquid crystal N-͑4-ethoxybenzylidene͒-2,6-dideutero-4-n-butylaniline are investigated using NMR spectroscopy. Seven separate samples containing differing concentrations of all solutes are investigated at constant temperature, at constant reduced temperature, at constant TCB orientational order, and at constant liquid crystal orientational order. Various schemes for comparison of orientational order among the samples are examined. For the experiments performed here, the most consistent method to compare solute orientational order in the different samples is to multiply results from the experiments performed at constant temperature by the factor needed to equate the TCB order parameters.

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Dipole-induced ordering in nematic liquid crystals. II. The elusive holy grail

Cited by 30 publications

References 42 publications

Molecules with Large-Amplitude Torsional Motion Partially Oriented in a Nematic Liquid Crystal: Ethane and Isotopomers

Molecules with Large-Amplitude Torsional Motion Partially Oriented in a Nematic Liquid Crystal: Ethane and Isotopomers

Orientational order of near D3h solutes in nematic liquid crystals

Effects of solute properties and concentrations on liquid crystals: N-(4-ethoxybenzylidene)-2,6-dideutero-4-n-butylaniline

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