2H NMR, lineshape analysis

Crystalline amino acids have often been used as model compounds for probing functional group interactions in proteins. The 3-site 120° jump motion of the ammonium (-NH3) group in alanine has been studied using 2H NMR lineshape analysis and by considering the anisotropy of the 2H spin-lattice relaxation [182]. The activation energy for this motion was estimated to be 40.5 kj mol-1. 

In the review period, studies on zeolite systems have proceeded much as before 2H NMR lineshape studies still predominate. However, the organic guest molecules now being considered are larger than previously. This brings with it added complications for the 2H lineshape analysis, at least for uniformly... 

The 2-site 120° jump motion for the basal molecules switches between these two hydrogen bonding arrangements and clearly requires correlated jumps of the hydroxyl groups of all three basal molecules. On the assumption of Arrhenius behaviour for the temperature dependence of the jump frequencies, the activation energies for the jump motions of the apical and basal deuterons were estimated to be 10 and 21 kj mol-1, respectively. This dynamic model was further supported by analysis of the dependence of the quadrupole echo 2H NMR lineshape on the echo delay and consideration of 2H NMR spin-lattice relaxation time data. 

We now consider some specific features of the most widely used 2H NMR technique - lineshape analysis - as well as other important 2H NMR techniques. More detailed discussion can be found in other review articles [27,28]. By employing appropriate combinations of these techniques, and exploiting the complementarity between them, a detailed understanding of the dynamic properties may be established. 

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