STRUCTURE OF MOLECULES BY NMR-SPECTROSCOPY USING LIQUID-CRYSTAL SOLVENTS

Nuclear magnetic resonance spectroscopy of molecules aligned in nemati c liquid crystalline media provides information on the molecular struc ture and order parameters. The partial alignment of the molecules in t he liquid crystalline phases gives rise to residual intramolecular dip olar couplings which are dependent on internuclear distances, and ther efore yield information on the structure of molecules. The dipolar cou plings are in general large compared to chemical shifts, and the spect ra become rapidly complex with the increase in the number of interacti ng spins and decrease of symmetry of molecules. In this article, the p rocedure for the analyses of such spectra is outlined in a pedagogical manner. The concept of the order parameter is illustrated in a phenom enological way. The utility of the technique and obtainable informatio n is demonstrated using practical examples. (C) 1998 John Wiley & Sons , Inc.