@article {334, title = {Isotropic-liquid crystalline phase diagram of a CdSe nanorod solution}, journal = {Journal of Chemical Physics}, volume = {120}, year = {2004}, note = {J Chem Phys763JETimes Cited:27Cited References Count:29}, month = {Jan 15}, pages = {1149-1152}, abstract = {

We report the isotropic-liquid crystalline phase diagram of 3.0 nm x 60 nm CdSe nanorods dispersed in anhydrous cyclohexane. The coexistence concentrations of both phases are found to be lower and the biphasic region wider than the results predicted by the hard rod model, indicating that the attractive interaction between the nanorods may be important in the formation of the liquid crystalline phase in this system. (C) 2004 American Institute of Physics.

}, keywords = {model}, isbn = {0021-9606}, doi = {Doi 10.1063/1.1640331}, url = {://WOS:000188081000002}, author = {Li, L. S. and Marjanska, M. and Park, G. H. J. and Pines, A. and Alivisatos, A. P.} } @article {326, title = {NMR studies of C-13-iodomethane: Different behavior in thermotropic and lyotropic liquid crystals}, journal = {Journal of Physical Chemistry A}, volume = {108}, year = {2004}, note = {J Phys Chem A846BMTimes Cited:9Cited References Count:38}, month = {Aug 19}, pages = {6809-6813}, abstract = {

High-resolution NMR spectra of C-13-iodomethane dissolved in thermotropic and lyotropic liquid crystalline solvents have been used to measure H-1-H-1 and C-13-H-1 dipolar couplings. The ratio of these two couplings, which is a function of the H-C-H bond angle in C-13-iodomethane, is, in general, different from that expected from the known molecular structure; solvent-solute interactions in liquid crystalline solutions are responsible for this difference. In thermotropic liquid crystalline solutions, the apparent bond angle deviation (Deltatheta(a)) increases with decreasing molecular ordering. In contrast, in lyotropic liquid crystals, no significant spectral aberration has been observed. These results indicate a fundamental physicochemical difference between the intermolecular interactions that prevail in thermotropic and lyotropic liquid crystals.

}, keywords = {biomolecules}, isbn = {1089-5639}, doi = {Doi 10.1021/Jp047330g}, url = {://WOS:000223289700001}, author = {Shahkhatuni, A. G. and Shahkhatuni, A. A. and Panosyan, H. A. and Park, G. H. J. and Martin, R. W. and Pines, A.} } @article {329, title = {Variable angle spinning (VAS) NMR study of solvent effects in liquid crystalline solutions of C-13-iodomethane}, journal = {Chemical Physics Letters}, volume = {399}, year = {2004}, note = {Chem Phys Lett874AXTimes Cited:5Cited References Count:28}, month = {Nov 21}, pages = {196-199}, abstract = {

NMR spectra of C-13-iodomethane oriented in three different liquid crystalline solvents have been collected and analyzed under spinning at various angles with respect to the static magnetic field. For each sample the ratio of homonuclear (H-1-H-1) to heteronuclear (C-13-H-1) dipolar couplings, which is a function of the geometry of the solute molecule, does not change significantly with the scaling of the dipolar couplings due to spinning at different angles. This result implies that the \&$\#$39;apparent bond angle deviations\&$\#$39; (Deltatheta(a)), previously calculated from thermotropic liquid crystals, arise from a solvent effect and are not an artifact from scaling the anisotropic interactions. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {phases}, isbn = {0009-2614}, doi = {Doi 10.1016/J.Cplett.2004.10.009}, url = {://WOS:000225324400036}, author = {Park, G. H. J. and Martin, R. W. and Sakellariou, D. and Pines, A. and Shahkhatuni, A. G. and Shahkhatuni, A. A. and Panosyan, H. A.} } @article {345, title = {Using switched angle spinning to simplify NMR spectra of strongly oriented samples}, journal = {Journal of the American Chemical Society}, volume = {125}, year = {2003}, note = {J Am Chem Soc695CXTimes Cited:13Cited References Count:38}, month = {Jul 2}, pages = {7998-8006}, abstract = {

This contribution describes a method that manipulates the alignment director of a liquid crystalline sample to obtain anisotropic magnetic interaction parameters, such as dipolar coupling, in an oriented liquid crystalline sample. By changing the axis of rotation with respect to the applied magnetic field in a spinning liquid crystalline sample, the dipolar couplings present in a normally complex strong coupling spectrum are scaled to a simple weak coupling spectrum. This simplified weak coupling spectrum is then correlated with the isotropic chemical shift in a switched angle spinning (SAS) two-dimensional (2D) experiment. This dipolar-isotropic 2D correlation was also observed for the case where the couplings are scaled to a degree where the spectrum approaches strong coupling. The SAS 2D correlation of C6F5Cl in the nematic liquid crystal I52 was obtained by first evolving at an angle close to the magic angle (54.7degrees) and then directly detecting at the magic angle. The SAS method provides a 2D correlation where the weak coupling pairs are revealed as cross-peaks in the indirect dimension separated by the isotropic chemical shifts in the direct dimension. Additionally, by using a more complex SAS method which involves three changes of the spinning axis, the solidlike spinning sideband patterns were correlated with the isotropic chemical shifts in a 2D experiment. These techniques are expected to enhance the interpretation and assignment of an isotropic. magnetic interactions including dipolar couplings for molecules dissolved in oriented liquid crystalline phases.

}, keywords = {solids}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0342244}, url = {://WOS:000183814500059}, author = {Havlin, R. H. and Park, G. H. J. and Mazur, T. and Pines, A.} } @article {363, title = {Two-dimensional NMR correlations of liquid crystals using switched angle spinning}, journal = {Journal of Magnetic Resonance}, volume = {157}, year = {2002}, note = {J Magn Reson589DHTimes Cited:10Cited References Count:28}, month = {Jul}, pages = {163-169}, abstract = {

We present the first application of switched angle spinning (SAS) to correlate the first-order dipolar spectrum of a liquid crystalline sample with the isotropic magic angle spinning (MAS) spectrum in a two-dimensional experiment. In this experiment we are able to select the degree of dipolar couplings introduced via mechanical manipulations of the liquid crystal director in a single oriented sample. The F-19 SAS-COSY correlation of iodotrifluoroethylene, an AMX spin system, dissolved in the nematic liquid crystal 4-octylphenyl-2-chloro-4-(4-heptylbenzoyloxy)-benzoate provides assignment of both the J and dipolar couplings in a single experiment. This work demonstrates the use of oriented samples and sample spinning to resolve hornonuclear dipolar couplings using isotropic chemical shifts. (C) 2002 Elsevier Science (USA).

}, keywords = {dynamics}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2002.2571}, url = {://WOS:000177742400020}, author = {Havlin, R. H. and Park, G. H. J. and Pines, A.} }