The infrared absorption spectrum of dextran and its bound water

Abstract Almost complete assignments are presented for the infrared absorption spectrum of dextran. These assignments were made by normal group analysis of the subaltern bands within the broad composite bands constituting the spectrum, and by examining the conclusions in the light of normal coordinate analysis of the repeat unit of this polymer. The α‐1,6‐glycosidic linkages in dextran have been found to result in lower intermolecular hydrogen bonding than in other glucans and this explains many features of the spectrum, including the occurrence of a variety of bands originating from different types of bound water. Particularly, a very strong band at 800 cm −1 corresponding to the libration vibration of ice, which occurs in the spectrum of freeze‐dried dextran, is of great interest and has been ascribed to “organized” water.