Qualitative motional description derivatives

Table I, which lists a number of mono-, oligo-, and polysaccharides and derivatives whose motional descriptions are available based on qualitative arguments, summarizes the experimental conditions and types of measurements used to obtain those descriptions. Table II deals specifically with those carbohydrates for which a quantitative treatment and dynamic modeling have been undertaken. In naming the compounds listed in Tables I and II, IUPAC rules are used for monosaccharide and less complex oligosaccharide molecules. However, empirical names are used for unusual oligosaccharides involving a complex aglycon substituent and polysaccharides. The gross motional features of a number of the compounds in Table I have been discussed in references 6-8, and will be mentioned here only if necessary for further clarification or for comparison with quantitative results.

In the first place, the averaged model equations are highly nonlinear and require sophisticated numerical analysis for solution. For example, the attempt to obtain numerical solutions for motions of polymeric liquids, based upon simple continuum, constitutive equations, is still not entirely successful after more than 10 years of intensive effort by a number of research groups worldwide [27]. It is possible, and one may certainly hope, that model equations derived from a sound description of the underlying microscale physics will behave better mathematically and be easier to solve, but one should not underestimate the difficulty of obtaining numerical solutions in the absence of a clear qualitative understanding of the behavior of the materials. 

We note that it is possible to use NMR data to obtain qualitative information about relative mobilities without a detailed knowledge of the dynamics. A semiquantitative description may be derived as well without knowledge of the type of motion actually occurring for example, several different internal models may all fit the data with approximately the same correlation time, implying that an internal motion in that time range exists. 

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