Cross-correlated relaxation evidence for the intramolecular C-H⋯N hydrogen bond in solution

Weak hydrogen bonds of the type C-H⋯N were proposed some years ago and increasing evidence for them in the solid state are being reported. We provide here indirect evidence for such an intramolecular hydrogen bond in solution. The evidence relies on experiments based on cross-correlated relaxation in liquids. A parameter describing the orientation of the CSA tensor of the hydrogen-bonded proton relative to a dipolar-coupled partner is observed to vary on uncoupling the interaction by adding a polar solvent reflecting the variation in the strength of hydrogen bond.