Selectivity in proton transfer, hydrogen bonding, and solvation.

The site of protonation (or deprotonation) of polyfunctional bases and acids can be determined through the comparison of experimental NMR properties (chemical shift and relaxation rates) with the corresponding data calculated by quantum chemical methods. The results can be interpreted in terms of the competition between intrinsic base strengths and solvation. Qualitatively similar criteria are found to hold for hydrogen bonding. The selective enrichment in a cosolvent in the solvation shell of a solute dissolved in a solvent mixture (preferential solvation) can be determined through the analysis of intermolecular cross-peak intensities in NOESY spectra.