Metal–ion interactions with sugars. The crystal structure and FTIR study of an SrCl2–fructose complex

Abstract

The single-crystal structure of SrCl2 x 2C6H12O6 x 3H2O was determined with Mr = 572.88, a = 16.252, b = 7.941(2), c = 10.751(3) angstroms, beta = 127.652(4) degrees, V = 1098.5(6) angstroms3, C2, Z = 2, mu = 0.71073 angstroms and R = 0.0296 for 1998 observed reflections. The fructose moiety of the complex exists as a beta-d-pyranose. The strontium atom is surrounded by eight oxygen atoms, which are arranged in symmetry-related pairs that are derived from four sugar and two water molecules. Three nonvicinal hydroxyl groups of fructose are involved in strontium binding. All the hydroxyl groups and water molecules are involved in forming an extensive hydrogen-bond network. The Sr-fructose complex is isostructural with the Ca-fructose complex, and the crystal structures and FTIR spectra of the two complexes are compared in this article. The O-H, C-O, and C-O-H vibrations are shifted, and the relative intensities changed in the complexes IR spectra, which indicate sugar metalation. By studying the metal-binding properties of fructose, it is hoped that such would aid in the understanding of the structural chemistry of metal ions interacting with saccharides, as an actual biological system, and thereby aid in the interpretation of some particular biological processes.