Knowledge Bank

Recent studies have demonstrated the existentce of four distinct effects which contribute to the displacement which the chemical shift of a solute undergoes when it is dissolved in a solvent: (a) bulk diamagnetic polarization (b) van der Waals interaction (c) “polar” interaction and (d) neighbour-molecule magnetic anisotropy effects. For gases, accurate expressions may be derived for each of the above contributions which yield good agreement with experiment. For the liquid phase satisfactory quantitative agreement between theory and experiment may be obtained for the case of polar and non-polar solutes in non-polar isotropic or anisotropic solvents. However, for polar or non-polar solutes in polar solvents qualitative agreement is possible.