1H NMR studies on the hydrogen-bonding network in mono-altro-β-cyclodextrin and its complex with adamantane-1-carboxylic acid Original Research Article

The hydrogen-bond network in mono-altro-β-cyclodextrin and in its inclusion complex with adamantane-1-carboxylic acid were investigated by 1H NMR spectroscopy using the chemical shifts, temperature coefficients and vicinal coupling constants of the exchangeable hydroxy protons. The chemical shifts of the 3-OH signals indicated that the hydrogen-bond network between the 2-OH and 3-OH groups was disturbed not only on each side of the altrose residue, but also along the whole dextrin chain. Upon addition of adamantane-1-carboxylic acid, altrose underwent a conformational change from the 1C4 to the OS2 form, allowing a more continuous belt of hydrogen bonding, as evidenced by the downfield shift experienced by the 3-OH proton signals of the glucose residues.