Condensed state molecular dynamics in sorbitol and maltitol: Mobility gradients and conformation transitions

Molecular mobility in sorbitol and maltitol is studied in order to understa nd their differences near the junction between the alpha and beta relaxatio ns. The molecular dynamics simulations performed on the polyols in their bu lls state give support to the C-13 NMR results and imply that the mobility of a carbon atom located at the extremity of the chain is higher than that of any other carbon. Moreover, the difference in carbon atoms mobility is g reater within the sorbitol moiety of maltitol than in sorbitol and seems in timately related to the junction temperature of the alpha and beta relaxati on processes. The reorientation of the C-H vectors as probed by NMR is show n to be mainly the effect of conformation transitions in the case of a carb on atom located at the end of the chain.