Molecular dynamics studies of the conformation of sorbitol

Abstract

Molecular dynamics simulations of a 3 m aqueous solution of D-sorbitol (also called D-glucitol) have been performed at 300 K, as well as at two elevated temperatures to promote conformational transitions. In principle, sorbitol is more flexible than glucose since it does not contain a constraining ring. However, a conformational analysis revealed that the sorbitol chain remains extended in solution, in contrast to the bent conformation found experimentally in the crystalline form. While there are 243 staggered conformations of the backbone possible for this open-chain polyol, only a very limited number were found to be stable in the simulations. Although many conformers were briefly sampled, only eight were significantly populated in the simulation. The carbon backbones of all but two of these eight conformers were completely extended, unlike the bent crystal conformation. These extended conformers were stabilized by a quite persistent intramolecular hydrogen bond between the hydroxyl groups of carbon C-2 and C-4. The conformational populations were found to be in good agreement with the limited available NMR data except for the C-2–C-3 torsion (spanned by the O-2–O-4 hydrogen bond), where the NMR data supports a more bent structure.

The significance of the amorphous potential energy landscape for dictating glassy dynamics and driving solid-state crystallisation

“…3(a)), in agreement with a previous report. 52 It is significant that the onset of the localised sub-regions occurs near 260 K, corresponding to the T ga of sorbitol, while significant localisation occurs near 180 K, corresponding to the T gb of sorbitol. An analysis of the time-evolution of dihedral angles in glassy sorbitol helps to uncover the changes in atomic dynamics that occur as a function of temperature in such disordered molecular solids.…”

Molecular Simulations of Dodecyl-β-maltoside Micelles in Water: Influence of the Headgroup Conformation and Force Field Parameters

“…, refs 27,28,29,30,31,32,33,34,35, 36,37,38,39,40). MD with alkyl-glycosides (such as alkyl- β - O -glucoside (C 8 Glc 1 ) or alkyl-β- O -galactoside (C 8 Gal)) have been also performed in the past, involving bilayers,41, 42, 43 micelles 44,45, 46, 47 or interacting with a plant protein 48.…”

The Interaction of Sorbitol with Caffeine in Aqueous Solution

“…A small difference was seen, however, between the average sorbitol conformation in this study and that reported previously. 22,23 This difference arises only in the terminal torsional angle, and may arise from intermolecular interactions between sugar solute molecules due to the large difference in concentrations between the two studies (infinite dilution in the previous work and 1 molal here), and perhaps the water model used.…”

“…9 The water molecules were modeled using the TIP4P model. 26 Therefore, with respect to previous simulations on sorbitol reported in the literature, 22,23 the present study introduces both a new force field and a new water model. The simulation was implemented following the general procedures previously used to simulate pure aqueous solutions of caffeine 9 and of caffeine in glucose and sucrose solution.…”

“…Although torsional bending at C2-C3 is commonly found in crystalline polymorphs of sorbitol 21 previous investigation of the conformational features of sorbitol in water (at 3 m) suggested that a number of different conformers were significantly present at this relatively high concentration. 22 The extended conformers were stabilized by a quite persistent intramolecular hydrogen bond between the hydroxyl groups of carbons C-2 and C-4. In another paper, Hatcher et al 23 found similar results with some minor differences in the presence of other less populated bent conformations in the middle part of the chain.…”