MOLECULAR RECOGNITION OF BETA-RIBOFURANOSIDES BY SYNTHETIC POLYPYRIDINE-MACROCYCLIC RECEPTORS

Artificial ribofuranoside receptors were designed and synthesized. The design of the polypyridine-macrocyclic receptors was based on the mul tipoint hydrogen bond complementarity between the receptors and methyl beta-D-ribofuranoside. The binding affinity of the receptors for the ribofuranoside in CDCl3 was very high (up to K-a = 5.2 x 10(3) M(-1)), so that even native ribose was extracted by them into such nonpolar s olvents. Selective extraction of ribose by the receptors\was observed: the extractabilities, or affinities to the receptors of various pento ses and hexoses decreased in the following order: ribose > deoxyribose congruent to lxyose congruent to xylose > fructose > arabinose > gluc ose congruent to mannose congruent to galactose. The selectivity is go verned by the OH direction and the whole size of the sugars as well as their shapes. Furthermore, fluorescence emission of the receptors was largely enhanced in the presence of methyl beta-D-ribofuranoside or r ibose, and the degree for the fluorescence enhancement by the addition of various sugars was almost compatible with that of the extractabili ties. The polypyridine-macrocycles represent rationally designed multi functional artificial receptors for ribofuranosides.