@inbook {doi:10.1002/9780470034590.emrstm1477, title = {Molecular Hydrogens Dissolved in Liquid Crystals}, booktitle = {eMagRes}, year = {2016}, pages = {901-912}, publisher = {American Cancer Society}, organization = {American Cancer Society}, abstract = {Abstract The NMR spectra of molecular hydrogen isotopologs dissolved and orientationally ordered in nematic liquid-crystal solvents provide a wealth of information. Because they are quantum rotors, the various isotopologs H 2 , D 2 , T 2 , HD, HT, and DT have different order parameters, with larger internuclear distance having smaller order parameter. The signs and magnitudes of the order parameters are liquid-crystal dependent, this being a direct result of the dominant anisotropic intermolecular interaction being that between the solute quadrupole moment and the mean liquid-crystal electric-field gradient (EFG) felt by the solute. Thus, the mixing of different liquid crystals can produce a solvent where molecular hydrogen feels a zero EFG, called a magic mixture. The remaining, dominant anisotropic interaction (for solutes larger than hydrogen) in these magic mixtures involves short-range anisotropic forces that depend on solute size and shape. Studies involving the very symmetrical methane H, D, and T isotopologs point out the important effect on dipolar couplings of molecular vibrations and interactions between molecular vibration and reorientation, effects which make it impossible to utilize fully the high accuracy with which dipolar couplings in general can be measured.}, keywords = {ANISOTROPIC, electric field gradient, HYDROGEN, liquid crystal, METHANE, NMR, order parameter, ordered liquids, ORIENTATION, VIBRATIONS}, isbn = {9780470034590}, doi = {10.1002/9780470034590.emrstm1477}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/9780470034590.emrstm1477}, author = {Burnell, E. Elliott and de Lange, Cornelis A.} } @article {1069, title = {Molecules with large-amplitude torsional motion partially oriented in a nematic liquid crystal: Ethane and isotopomers}, journal = {Journal of Physical Chemistry A}, volume = {109}, number = {48}, year = {2005}, note = {ISI Document Delivery No.: 990RPTimes Cited: 10Cited Reference Count: 48}, month = {Dec}, pages = {11027-11036}, type = {Article}, abstract = {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 reorientation-vibration 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.}, keywords = {ANISOTROPIC, ELECTRIC-FIELD GRADIENTS, ENVIRONMENTS, FORCE-FIELDS, H-2 NMR, NUCLEAR-MAGNETIC-RESONANCE, orientational order, POLYATOMIC-MOLECULES, ROTATION, SPECTRA, VIBRATIONS}, isbn = {1089-5639}, url = {://000233761200026}, author = {Burnell, E. E. and de Lange, C. A. and Barnhoorn, J. B. S. and Aben, I. and Levelt, P. F.} }