Solution properties of low molecular weight polyhydroxy compounds

Summary

Introduction

Historical perspective: scope of review

Polyhydroxy compounds (PHC) in general, and carbohydrates in particular, have until recently been the preserve of the organic chemist. The emphasis has been on synthesis, stereochemistry, derivatization, reaction mechanisms and, more recently, crystal structures. During the past decade biochemical interest in sugars has grown, partly from the realization that oligosaccharide chains (attached to proteins) may have important biological functions. A recent review, entitled ‘Glycobiology’, in which glycosylation mechanisms are discussed in depth, well illustrates the increasing importance of this new subdiscipline.

PHCs are characterized by their polar nature and their ability to participate in hydrogen bonding, both as donors and acceptors. As a class of chemical compounds they therefore display a high affinity for water and other polar solvents. It is to be expected that solute–solvent hydrogen bonding plays some role in determining the structures and conformations of PHCs in solution, and indirectly, also their interactions with one another, perhaps even intramolecular interactions. Surprisingly, until quite recently, little attention was paid to such problems; the solution chemistry of simple carbohydrates was almost non-existent. Suggett, in what is probably the first criticial review of the subject, concluded that throughout the vast literature devoted to polysaccharides, water ‘… was treated implicitly as the universal inert filler’. This situation is almost as true today as it was in 1975 when the observation was made.

The aim of this review is to summarize and analyse the present state of our knowledge regarding the influence of solvation interactions on the structural, equilibrium and dynamic properties of monomeric and oligomeric PHCs, with a few short excursions into the realm of their polymers.