Exploring conformational energy landscape of glassy disaccharides by CPMAS 13C NMR and DFT/GIAO simulations. II. Enhanced molecular flexibility in amorphous trehalose

TL;DR

This study combines NMR simulations and DFT calculations to analyze the conformational flexibility of amorphous disaccharides, revealing that trehalose exhibits notably enhanced molecular flexibility linked to its hydrogen bonding network.

Contribution

It introduces a combined computational and experimental approach to characterize conformational distributions in amorphous sugars, highlighting trehalose's unique flexibility.

Findings

Trehalose shows increased conformational flexibility in the amorphous state.

The flexibility correlates with the hydrogen bonding network.

Simulations reliably interpret experimental NMR data.

Abstract

This paper deals with the comparative use of the chemical shift surfaces to simulate experimental 13C CPMAS data on amorphous solid state disaccharides, paying particular attention to -1-1 linkage of trehalose, to -1,4 linkage between pyranose rings (lactose) and to linkage implying a furanose ring (sucrose). The combination of molecular mechanics with DFT/GIAO ab-initio methods provides reliable structural information on the conformational distribution in the glass. The results are interpreted in terms of an enhanced flexibility that trehalose experiences in amorphous solid state compared to the other sugars. An attempt to relate this property to the balance between intra- and inter-molecular hydrogen bonding network in the glass is presented.