Native Mannose-Dominant Extraction by Pyridine-Phenol Alternating Oligomers Having an Extremely Efficient Repeating Motif of Hydrogen-Bonding Acceptors and Donors

Pyridine-phenol alternating oligomers in which pyridine and phenol moieties are alternatingly linked through acetylene bonds at the 2,6-positions of the aromatic rings were designed and synthesized. The pyridine nitrogen atom and the neighboring phenolic hydroxyl group were oriented so that they do not form an intramolecular hydrogen bond but cooperatively act as hydrogen-bonding acceptor and donor in a push-pull fashion for the hydroxyl group of saccharides. The longer oligomer strongly bound to lipophilic glycosides in 1,2-dichloroethane, and association constants approached 10⁸M^-1. Moreover, the oligomer extracted native saccharides from a solid phase to apolar organic solvents up to the extent of an equal amount of the oligomer and showed mannose-dominant extraction among naturally abundant hexoses. The oligomer bound to native saccharides even in 20% DMSO-containing 1,2-dichloroethane and exhibited association constants of greater than 10M^-1 for D-mannose and D-glucose.