Molecular solutes in nematic liquid crystals: Orientational order and electric field gradients

Patey, G. N.; Burnell, E. Elliott; Snijders, J.G.; Lange, C.A. de

doi:10.1016/0009-2614(83)87539-3

Cited by 84 publications

(65 citation statements)

References 17 publications

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“…7,12,13 Our current results lend strong support to the notion that average external electric field gradients present in liquid-crystal solvents should not be ignored in the interpretation of measured quadrupolar couplings.…”

Section: Introductionsupporting

confidence: 78%

“…7,12,13 The discrepancies between experimental and calculated quadrupolar couplings were resolved by assuming that an average external electric field gradient present in the liquid-crystal solvent interacts with the deuterium nuclei in the solutes. The quadrupolar couplings obtained for the deuterated ethanes in this work show very similar discrepancies.…”

Section: Discussionmentioning

confidence: 99%

“…The application of vibrational corrections to the experimental quadrupolar couplings is notoriously complicated and is therefore neglected. 46 7,12,13 the discrepancies between experimental and calculated quadrupolar couplings, B D external , are ascribed to the presence of an average external electric field gradient (at the site of the deuteron nucleus) provided by the liquid-crystal environment Extensive previous studies have shown that for ZLI 1132 and EBBA the average external field gradients are of similar magnitude but of opposite sign. Because a reliable experimental value for eV | rig Q D /h does not exist, we adjust its value to 177.9 kHz to obtain an equal but opposite discrepancy in the quadrupolar couplings measured in ZLI 1132 and EBBA.…”

Section: Ethane Dipolar Couplingsmentioning

confidence: 93%

“…Second, small probe molecules have proved to be extremely valuable in elucidating details about the intermolecular anisotropic potential in orientionally ordered liquids and about the mechanisms that contribute to the orientational order of such solute species. 2,3 Seminal papers in this field have employed molecular hydrogen [4][5][6] and its deuterated [7][8][9] and tritiated 10 isotopomers, as well as methane and its isotopomers. [11][12][13] From such studies, it has become apparent that in liquid-crystal solvents both short-and long-range interactions generally contribute to the orientational order.…”

Section: Introductionmentioning

confidence: 99%

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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: Introductionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: Ethane Dipolar Couplingsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

et al. 2005

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“…Estimates of the average electric ®eld gradient, F ZZ , experienced by D 2 [2,3] have been determined from deuterium NMR. Experiments on larger methyl-and chloro-substituted benzenes indicate that these larger solutes experience an F ZZ of the same sign but reduced magnitude compared to that observed for D 2 [4±6].…”

Section: Introductionmentioning

confidence: 99%