Two−Dimensional Multiple Quantum N.M.R. of Isotopic Mixtures in Liquid Crystals

A technique is presented for the experimental determination and assignment of dipolar coupling constants from the N.M.R. spectra of molecules dissolved in liquid crystals. The technique is applicable to larger molecules than have been studied to date. Random deuteration of the molecule results in a statistical mixture of partially protonated species which can be analysed by two-dimensional and multiple quantum N.M.R. techniques to determine and assign all the dipole coupling constants. Benzene is used as an illustrative example.