@article {2526, title = {Evolutionary algorithms to solve complicated NMR spectra}, journal = {Journal of Chemical Physics}, volume = {130}, number = {4}, year = {2009}, note = {ISI Document Delivery No.: 401TJTimes Cited: 3Cited Reference Count: 37Meerts, W. Leo de Lange, C. A. Weber, A. C. J. Burnell, E. E.}, month = {Jan}, pages = {8}, type = {Article}, abstract = {The complexity of H-1 NMR spectra of solutes in partially ordered solvents such as liquid crystals increases rapidly with the number of spins. Spectra of simple solutes with sufficient symmetry and containing not too many spins (typically <= 8) are readily analyzed. The analysis of larger spin systems is more difficult, and often impossible. In this paper we present the application of a general automated evolutionary algorithm to solve the highly complex proton NMR spectrum of the 12-spin system pentane, a solute that interconverts rapidly among several symmetry-unrelated conformations. The interpretation of the spectral parameters that are obtained from the analysis requires the use of a model to connect relative orientational orders in symmetry-unrelated conformers.}, keywords = {ALKYL CHAINS, AUTOMATED-ANALYSIS, evolutionary computation, HIGH-RESOLUTION NMR, liquid crystals, magnetic resonance, MOLECULAR-STRUCTURE, MULTIPLE-QUANTUM SPECTRA, NEMATIC LIQUID-CRYSTALS, ORDER, organic compounds, PROTON, SHAPE, SOLUTES, spectroscopy computing, STRATEGY}, isbn = {0021-9606}, url = {://000262965000028}, author = {Meerts, W. L. and de Lange, C. A. and Weber, A. C. J. and Burnell, E. E.} } @article {4115, title = {Orientational order of 1,3-dichloro-2-ethenylbenzene in liquid crystal solvents}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {75}, number = {8}, year = {1997}, note = {ISI Document Delivery No.: XX043Times Cited: 2Cited Reference Count: 38}, month = {Aug}, pages = {1156-1161}, type = {Article}, abstract = {The order parameter matrices of a molecule that has no symmetry, 1,3-dichloro-2-ethenylbenzene, dissolved in two different nematic liquid-crystal solvents are analyzed in terms of various models for the intermolecular mean-field potential. In a mixture of liquid crystals for which the interaction between the molecular quadrupole moment tensor and the average electric field gradient of the nematic solvent has been minimized, the orientational order is best described by models for the short-range anisotropic potential. The most successful potentials are written in terms of anisotropic interactions between the solute surface and the liquid-crystal mean field. This represents a strong test of such models because they simultaneously fit the five independent orientational parameters obtained from the same solute, thus removing the problems associated with comparing results among different solutes in either the same or a different sample tube.}, keywords = {ALKYL CHAINS, ANISOTROPIC, FIELD, INTERMOLECULAR FORCES, liquid crystals, MAGNETIC-RESONANCE, MIXTURES, MOLECULES, NEMATIC SOLVENT, NMR, order parameters, PHASES, SHAPE, SOLUTES}, isbn = {0008-4042}, url = {://A1997XX04300014}, author = {Rendell, J. C. T. and Zimmerman, D. S. and vanderEst, A. J. and Burnell, E. E.} } @article {3487, title = {CONFORMATIONAL EQUILIBRIUM AND ORIENTATIONAL ORDERING - H-1-NUCLEAR MAGNETIC-RESONANCE OF BUTANE IN A NEMATIC LIQUID-CRYSTAL}, journal = {Journal of Chemical Physics}, volume = {103}, number = {16}, year = {1995}, note = {ISI Document Delivery No.: TA441Times Cited: 25Cited Reference Count: 60}, month = {Oct}, pages = {6891-6902}, type = {Article}, abstract = {In this study we use multiple-quantum H-1-NMR spectroscopy to study butane, the simplest flexible alkane, dissolved in a nematic solvent. An analysis of the highly accurate H-1 dipolar coupling constants gives important information about conformational and orientational behavior, including the hans-gauche energy difference, E(tg), and the conformer probabilities and order parameters. An essential component of the analysis involves the use of mean-field models to describe the orientational ordering of solutes in a nematic solvent. Several models were found to adequately describe the molecular ordering, including the chord model of Photinos et al. [D. J. Photinos, E. T. Samulski, and H. Toriumi, J. Phys. Chem. 94, 4688 (1990)] and recent versions of a model proposed by Burnell and co-workers [D. S. Zimmerman and E. E. Burnell, Mel. Phys. 78, 687 (1993)]. It was found that E(tg) lies in the range 2.1-3.0 kJ/mol, which is significantly below most experimental estimates of the gas-phase value. An attempt to describe more realistically the conformational states by including torsional fluctuations about the rotational isomeric states did not significantly improve the quality of the fits or alter the results. Finally the anisotropic component of the solute-solvent interaction was found to perturb only marginally the conformational probabilities from the isotropic values. (C) 1995 American Institute of Physics.}, keywords = {ALKYL CHAINS, ANISOTROPIC LIQUIDS, ELECTRON-DIFFRACTION, INTERNAL-ROTATION, MOLECULAR-DYNAMICS, N-BUTANE, NORMAL-HEXANE, POTENTIAL FUNCTION, PROTON DIPOLAR COUPLINGS, STATISTICAL-MECHANICS}, isbn = {0021-9606}, url = {://A1995TA44100007}, author = {Polson, J. M. and Burnell, E. E.} } @article {3270, title = {AN ORIENTATIONAL STUDY OF SMALL SOLUTES IN ZERO ELECTRIC-FIELD GRADIENT NEMATIC LIQUID-CRYSTAL MIXTURES}, journal = {Journal of Physical Chemistry}, volume = {99}, number = {18}, year = {1995}, note = {ISI Document Delivery No.: QW705Times Cited: 2Cited Reference Count: 32}, month = {May}, pages = {7054-7059}, type = {Article}, abstract = {The solutes m-dichlorobenzene, o-dichlorobenzene. p-dichlorobenzene, o-dicyanzene, furan, tetrathiofulvalene, and fluorobenzene are studied in the zero electric field gradient mixtures 56.5 wt \% 1132/EBBA and 70 wt \% 5CB/EBBA using proton NMR. The two second-rank-order parameters obtained for each solute from analysis of the NMR spectra indicate that the solutes experience a similar anisotropic potential in both mixtures. The results are interpreted in terms of two models for the short-range anisotropic potential experienced by the solutes.}, keywords = {ALKYL CHAINS, BEHAVIOR, DIPOLE INTERACTIONS, MEAN TORQUE, MOLECULES, PHASE, POTENTIALS, SHAPE, SIZE, SOLVENTS}, isbn = {0022-3654}, url = {://A1995QW70500043}, author = {Chandrakumar, T. and Smith, L. and Burnell, E. E.} }