STRUCTURAL APPLICATIONS OF NUCLEAR SPIN-LATTICE RELAXATION TIMES

Abstract- The structural utility of three mechanisms of nuclear spin relaxation are considered. Examples illustrating the applicability of nuclear-nuclear dipolar relaxation in determining molecular microdynamics and solution geometry are presented. The use of spin-rotation relaxation to determine barriers to CH3 groups rotations and an example of quadrupole relaxation of deuteriums to probe molecular motion are discussed. An experimental method for determining relaxation times is briefly analysed. INTRODUCT ION Structural applications of nuclear magnetic resonance spectroscopy have usually only involved chemical shift (c) and coupling constant (J) considerations. The reasons for this are manifold, the main ones include: (a) most commercial instruments have been CW-based and the measurement of any other magnetic resonance parameter besides i or J is difficult, and (b) the technology for the measurement of the spin-lattice (Ti) relaxation time of a single resonance line in a multi-line spectrum has only been available since the development of FT based spectrometers. The major break-throughs here being the cheap cost of on lin