Interactions of Hydroxy Compounds and Sugars with Anions1

Abstract

Complexations of aliphatic monohydroxy compounds, of trans-1,2 cyclohexanediol, and of several glucose and galactose derivatives with two to four free hydroxy groups are measured in chloroform with peralkylammonium salts containing different anions. It is shown that NMR titrations with up to four different OH signals as well as with some CH signals allow accurate and consistent calculation of equilibrium constants K and complexation induced shifts (CIS). The anions used generally show an increasing affinity in the order iodide < benzenesulfonate < bromide < diphenyl phosphate < chloride < benzenecarboxylate (benzoate). The K values increase from secondary to primary alcohols, and again substantially to vicinal diols, culminating at up to K = 103 M-1 for 1-dodecyl glucose or galactose compounds. The observed CIS and K values agree with the formation of 3 different 1:1 complexes of similar stability for the phosphate receptor, with binding one anion between the 2-, 3-, 4-, and 6-OH groups of the glucoside, or only one 1:1 complex in the interaction of halides with sugars. Vicinal 3JHOCH coupling constants are analyzed before and after complexation and provide insight into the hydrogen bond network of the sugar derivatives.