The effect of anomerism and hydration on the C-O-S vibrational frequency of d-galactose-3-sulfate determined by FTIR spectroscopy

The effect of the anomeric structure of d-galactose-3-sulfate (potassium salt) on its spectral characteristics was studied by 1H and 13C NMR and FTIR spectroscopy under a variety of conditions. The synthetic product in D2O was a mixture of α and β galactopyranose-3-sulfate. Crystallization from 80% ethanol yielded the α anomer in a high state of purity. The FTIR spectrum of the C-O-S vibrational bands in the region 900–800 cm−1 depended on the anomeric structure and on hydration. In the dry state the α anomer had a band at 868 cm−1, while the β anomer had bands at 882 and 831 cm−1. In D2O the band at 868 cm−1 shifted down to 849 cm−1 for the α anomer and that at 831 cm−1 shifted down to 821 cm−1 for the β anomer. These differences in frequency will be useful as a diagnostic tool in determining the configuration at C-1 of galactose-3-sulfate units present in many molecules of biological importance. © 1997 Elsevier Science Ltd.