Carbohydrate Recognition through Noncovalent Interactions: A Challenge for Biomimetic and Supramolecular Chemistry

Abstract

Carbohydrates are not always as "sticky" as one might expect. Even in organic solvents they are difficult targets for the supramolecular chemist, due to their complex, three-dimensional structures. In their natural environment (water) they are especially elusive, presenting challenges which will occupy synthetic and theoretical chemists for some time to come. The complex of an octaamide supramolecular receptor with beta-D-glucopyranose, which binds through apolar and polar contacts, is shown.

Phase transfer of monosaccharides through noncovalent interactions: Selective extraction of glucose by a lipophilic cage receptor

“…However, after 0.2 equivalents had been added, all aromatic CH signals broadened significantly, whereas CHa, as well as the signal due to NH, became almost indistinguishable from baseline and therefore impossible to follow for binding constant calculations. It is clear that a strong interaction was occurring between the macrocycle and the sugar, but quantification was not possible by 1 …”

“…C arbohydrate recognition is an active area of supramolecular chemistry, motivated by the biological importance of saccharides and also by the unusual challenge represented by these complex substrates (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). On the one hand, carbohydrates must be recognized and processed during metabolism, whereas saccharide motifs are known to mediate cell-cell recognition, the infection of cells by pathogens, and many aspects of the immune response (14)(15)(16)(17).…”

“…On the other, carbohydrates possess structures that are fairly large, irregular, and multivalent, while being quite similar to clusters of water molecules. Even in nonpolar solvents, selective carbohydrate receptors require extended, sophisticated architectures (1,(3)(4)(5)(6). In the presence of liquid water, the problem becomes yet more difficult.…”

“…In the presence of liquid water, the problem becomes yet more difficult. Recognition by means of boronate formation has been relatively successful (2,(7)(8)(9)(10), but there are few effective systems for binding saccharides from water by using noncovalent bonds (1,(11)(12)(13).…”

Principles, Concepts and Strategies of Stereoselective Synthesis

“…Discriminative interactions and complexations of a chiral host (e.g., extractant) with enantiomers of a chiral guest (racemate that has to be resolved) bearing stereocenter(s) provide an opportunity for the enantiomer recognition and separation. A wide variety of discriminative interactions has been reported, among them anion recognition, [121][122][123] peptide and protein recognition, 124,125 carbohydrate recognition, 126 and recognition of carboxylic acids, 127 amino compounds, 128,129 and neutral molecules. 130 After the addition of a chiral lipophilic host or extractant confined in the organic phase, a host-mediated phase transfer of the substrate occurs.…”