Application of 1H NMR bi‐selective relaxation times to conformational analysis in solution

The usefulness of 1H bi‐selective relaxation times (T ) and selective relaxation times (T ) for structure and conformation determination is emphasized. A pulse sequence has been devised which provides the apparent observed T . The cross‐relaxations (σij) or Fij values are derived from the observed T and T values. The σij values can be correlated with the HH distances (rij) and can be used for conformational analysis or structure determination. The Fij values, which indicate the fractional contribution to the dipolar relaxation of proton i via the interaction with proton j(i ≠ j), can be compared with the NOE values. 2‐Vinylpyridine was chosen as a model compound and three types of T1 values were measured for its protons. Its conformation in CDCl3 solution is discussed based on the correlation between the σij obtained and the rij values. A conformational equilibrium is suggested.