Sugar-metal ion interaction: Crystal structure and spectroscopic study of potassium chloride complex with D-glucose, KCl•2C6H12O6

Potassium ion plays an important role in a variety of bioactivities, and many functions of potassium ion are exerted via coordination with saccharides. Up to now, the understanding of the biochemistry of K+/saccharides system is limited due to the lack of crystal structures of potassium ion-saccharide complexes. Herein, we have prepared single crystal of potassium chloride-alpha-D-glucose complex (KCI center dot 2C(6)H(12)O(6)) and its crystal structure has been successfully obtained. Potassium ion is coordinated to two a-D-glucose molecules. One alpha-D-glucose molecule provides 4 alpha and 6 beta hydroxyl groups to coordinate to potassium ion, another one uses its 2 alpha and 3 beta hydroxyl groups to coordinate to potassium ion. The single crystal structure of the complex exhibits some unusual structural features. K center dot center dot center dot K dimer is suggested to form because of shorter K center dot center dot center dot K distance (3.059 angstrom). Moreover, unusually short O center dot center dot center dot Cl distances between 2.3 and 2.5 angstrom are found in the crystal. Based on the crystal structure of the complex and the fact no free OH stretching vibrational absorption band is observed in FTIR spectra of the complex, assignment of hydrogen bonding linkage is achieved. Coordination with potassium ion brings about considerable structure variation on the glucose moiety of the complex. The structural changes can be reflected in the corresponding FTIR, Raman, FIR and THz spectra. (C) 2019 Elsevier B.V. All rights reserved.