Crystal structures of cellulosic crystals with amine molecules were characterized by X-ray and neutron fiber diffraction as well as computer simulations. We observed two important structural features: 1) Cellulose ammonia complex took an unkown crystalline phase we call quenched ammonia cellulose in liquid ammonia under 200� K; and 2) Most of the amine complexes exhibited the similar interactions between amines and cellulosic chains in the crystal.  Amine molecules dominantly accept the hydrogen bonds from hydroxyl group in glucan-chain, resulting in significant changes on hydrogen bonding system in the chain. This conversion of hydrogen bonds is accompanied by the conformational change on hydroxymethyl groups, i.e., majority of the hydroxymethyl groups of amine complexes take the gt conformation whereas those of anhydrous crystal or of the other solvent complexes have conformational variety. Because the hydroxymethyl group is related to intra-crystal and surface properties as well as chemical properties, it is important to know how this functional group is interacted with surrounding solvent molecules. We could observe the similar interactions between nitrogen atoms on amines and hydroxymetyl group, at least in the complexed crystal. Our results in this study can help the understanding of cellulosic material properties under various conditions.

Crystalline transition mechanism by amine molecules during complexation process: Crystal structure of polysaccharides-amine complexes

247th National Meeting (2014)

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