ISSN:0021-2148    

DOI:10.1002/ijch.198300036

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

ISSN:0021-2148    

DOI:10.1002/ijch.198300037

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe application of NMR spectroscopy in oriented media to the determination of molecular geometries is illustrated by results for three distinctly different molecules: naphthalene, ethylene oxide and spiropentane. The need for systematic application of vibrational corrections is emphasized and some of the effects associated with the different choices of solvent media are considered.

ISSN:0021-2148    

DOI:10.1002/ijch.198300038

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractWe have determined the elements of the1H– and13C‐chemical shift tensors of ethylene‐1,2–13C dissolved in various liquid crystals with methane –13C as a reference substance. The1H‐results have the same relative order of magnitude as the theoretical predictions. The13C‐results agree perfectly with theory but differ slightly from solid state data. Deviations must be attributed to variations in local effect contributions to the shifts in the various solvents which cannot

ISSN:0021-2148    

DOI:10.1002/ijch.198300039

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractA general molecular theory for the description of the orientation of small molecules in anisotropic environments is presented. Assuming a second‐order tensorial interaction between some solute property βijand the anisotropy in a liquid‐crystal “field”Fijrigid and non‐rigid contributions to the dipolar and quadrupolar couplings observable by NMR are evaluated. The behaviour of the solutes hydrogen, methane and their deuterated analogues in nematic phases can be described by special cases of this general theory and excellent agreement between observed and calculated anisotropic couplings is obtained. The present results suggest that the coupling between the solute molecular quadrupole moment and the anisotropy in the liquid‐crystal electric field gradient plays a significant role in the orienting process in the case

ISSN:0021-2148    

DOI:10.1002/ijch.198300040

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe problem of obtaining information on the molecular properties of non‐cylindrically symmetric solute molcules in liquid crystals is examined. Nitrobenzene, tetrafluoro‐p‐benzoquinone and pyridine have been investigated in various nematic solvents at a series of temperatures using proton, fluorine and deuterium NMR where relevant. The ordering matrices for these essentially rigid molecules have been determined as a function of temperature. The predictions of a mean field theory for solutes deviating from cylindrical symmetry are considered. The relative importance of polarizability, steric forces and specific interactions in determining orientational ordering is disc

ISSN:0021-2148    

DOI:10.1002/ijch.198300041

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe deuterium quadrupole coupling constants of chloroform and methylenechloride have been determined as 174.7 ± 0.5 kHz and 167.8 ± 1.3 kHz, respectively. The values were determined from the quadrupole splitting and the13C,2H dipole–dipole couplings obtained from the natural abundance13C‐satellites in the2H‐NMR spectrum of the molecules in nematic phase. The dipole‐dipole coupling has been corrected for vibration

ISSN:0021-2148    

DOI:10.1002/ijch.198300042

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractMeasurements of the nitrogen‐14 and deuterium quadrupolar splittings in NH4NO3and (CH3)4N NO3dissolved in the disodiumcromoglycate–water liquid crystalline system are presented. Nitrogen‐14T1values in aqueous solutions for these salts are also given. The results are discussed and compared with similar studies on solutes containing14N in ordered

ISSN:0021-2148    

DOI:10.1002/ijch.198300043

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractTheory and applications of NMR spectra of molecules oriented in mixed liquid crystals of opposite diamagnetic anisotropies are presented. The theoretical treatment is based on the Landau theory. The applications include a novel method for the determination of chemical shift anisotropy, individual determination of the indirect spin‐spin and direct dipole–dipole couplings, determination of diamagnetic anisotropy of liquid crystals and precise determination of spectral paramet

ISSN:0021-2148    

DOI:10.1002/ijch.198300044

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of dynamic processes on the lineshapes of NMR spectra in liquid crystalline solutions is discussed. The discussion includes dynamic1H spectra ofs‐trioxane, cyclooctatetraene and bullvalene undergoing, respectively, ring inversion, bond shift and bond rearrangement. Also discussed are dynamic deuteron spectra using the examples of cyclohexane‐d12andp‐dioxane‐d8undergoing ring inversion. Finally the formalism required to simulate dynamic NMR spectra in liquid crystalline solution is reviewed and the possible factorization of the problem by symmetry considerations is di

ISSN:0021-2148    

DOI:10.1002/ijch.198300045

出版商:WILEY‐VCH Verlag    

年代:1983

数据来源: WILEY