We propose to use the temperature dependence of laboratory frame cross-relaxation rate to deduce the absolute value of interproton distances in solutions. For rigid molecules undergoing isotropic random motion, the cross relaxation rate becomes zero at a characteristic temperature T0, while at a higher temperature Tmax it reaches its maximum. At Tmax the correlation time is precisely defined and the interproton distance can be calculated directly from the cross-relaxation rate. The applicability of the method is tested on a small model compound, cyclo-(L-Pro-Gly). For the geminal proton pair of glycine, the measured distance of 1.89 ± 0.011 Å disagrees with the model value beyond the experimental error, indicating that the accepted model parameters need to be reevaluated.
|Original language||English (US)|
|Number of pages||15|
|Journal||Journal of the Serbian Chemical Society|
|State||Published - 1997|
ASJC Scopus subject areas