Nuclear magnetic resonance order parameters

Holte LL, Peter SA, Sinnwell TM. Gawrisch K. -H nuclear magnetic resonance order parameter profiles suggest a change of molecular shape for phosphatidylcholines containing a polyunsaturated acyl chain. Biophys J 1995 68 2396-2403. 

Probing Short and Medium Range Order in Al-based Fluorides using High Resolution Solid State Nuclear Magnetic Resonance and Parameter Modelling... 

Zannoni C 1985 An internal order parameter formalism for non-rigid molecules Nuclear Magnetic Resonance of Liquid Crystals ed J W Emsiey (Dordrecht Reidel)... 

Solid-state nuclear magnetic resonance (NMR) has been extensively used to assess structural properties, electronic parameters and diffusion behavior of the hydride phases of numerous metals and alloys using mostly transient NMR techniques or low-resolution spectroscopy [3]. The NMR relaxation times are extremely useful to assess various diffusion processes over very wide ranges of hydrogen mobility in crystalline and amorphous phases [3]. In addition, several borohydrides [4-6] and alanates [7-11] have also been characterized by these conventional solid-state NMR methods over the years where most attention was on rotation dynamics of the BHT, A1H4, and AlHe anions detection of order-disorder phase transitions or thermal decomposition. There has been little indication of fast long-range diffusion behavior in any complex hydride studied by NMR to date [4-11]. 

Thus our prediction for the mechanism of some Sn2 reactions in dipolar aprotic solvents is that they involve an initial complexation before the ratedetermining step. This provocative proposal finds some support in nuclear magnetic resonance (NMR) studies of aryl halides in acetonitrile, and the idea has recently been used to rationalize kinetic data for S 2 reactions in DMSO. It should be realized that the free energy profiles for 8, 2 reactions in solution have been largely a matter of conjecture the accessible experimental data on kinetic order and activation parameters do not characterize the pmfs in detail. Unimodal profiles in all solvents are commonly assumed in the literature. 

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