Molecular Interactions in an α-Chitin/Hydrazine Complex: Dynamic Hydrogen Bonds and Improvement of Polymeric Crystallinity

The high-resolution structure of an alpha-chitin/hydrazine complex has been determined to reveal the molecular interactions between hydrazine molecules and chitin chains. The complexation with guest hydrazine molecules improves the crystallinity of alpha-chitin from the original form, so that the primary hydroxyl group is dearly located in the gt position on the chitin chains arranged in an antiparallel manner in contrast to the original alpha-chitin structure-which has the disorder between gt and gg positions. During, the complexation process, alpha-chitin chains translate by c/4 to incorporate hydrazine molecules. Molecular dynamics calculations based on the refined structure show that hydrazine nitrogen atoms are disordered with competing hydrogen bonds. These observations suggest a mechanism for the structural conversion of polysaccharides to their crystal solvate forms during penetration by amine molecules.