Temperature effects hydrogen bond relaxation

The spin-lattice relaxation time 7] as a function of temperature T in liquid water has been studied by many researchers [387-393], and in all the experiments the dependence T (T) showed a distinct non-Arrhenius character. Other dynamic parameters also have a non-Arrhenius temperature dependence, and such a behavior can be explained by both discrete and continuous models of the water structure [394]. In the framework of these models the dynamics of separate water molecules is described by hopping and drift mechanisms of the molecule movement and by rotations of water molecules [360]. However, the cooperative effects during the self-diffusion and the dynamics of hydrogen bonds formation have not been practically considered. 

A very extensive study of iV,iV -di-(2-hydroxynaphthylmethylene)-p-phenylenediamine (49)171 exploits both spin-lattice relaxation times of protons and N CP-MAS spectroscopy at low temperature. Very low barriers are observed for the tautomeric processes 8 kJ mol for NH,NH NH,OH (converting one of the NH forms to an OH form) and 2 kJ moR for OH,OH NH,OH. Furthermore, the effect of one hydrogen bond propagates to the other one . ... 

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