NMR Study Conformations of Calcium Gluconate in the Aqueous Solution

Abstract

Different spatial structures that arise due to rotation around simple bonds without violating the integrity of the molecule (without breaking chemical bonds) are called conformations. ¹H nuclear magnetic resonance (NMR) study of the spatial structure of calcium gluconate in the aqueous solution has been carried out. It was shown that molecules of calcium gluconate exist in the form of two conformations: zigzag 1-P and cyclic ₃G⁺. The results of homonuclear 2D ¹H NMR spectroscopy indicate the predominantly zigzag conformation. It was found that the intermolecular hydrogen bonds are formed and the spatial structure of molecules changes at the increase in the solution concentration. The observed concentration behavior of the conformation of calcium gluconate is also associated with the presence of the intramolecular hydrogen bonds –O(C4)H··O(C2).