Study of the interaction of KF with carbohydrates in DMSO-d6 by 1H and 13C NMR spectroscopy

The interaction of KF with sugars (d-glucose, d-xylose, d-galactose, d-ribose, d-mannose, d-lyxose, cellobiose, maltose, maltotriose, amylose, saccharose and γ-cyclodextrin) were studied by 1H and 13C NMR spectroscopies in DMSO-d6. The main interactions are of the hydrogen bonding type between the sugar hydroxyl protons and the F− anions of KF. The shifts in mutarotation toward the β anomers are due to the breaking of the (OH)1⋯(OH)2 intramolecular hydrogen bonds by F−, which destabilizes the α form in glucose, xylose, galactose and ribose. KF also attacks and breaks intermolecular hydrogen bond bridges as those observed between (OH)2 and (OH)3′ groups of neighboring hexose units in amylose.