Molecular and crystal structures of chitosan/HI type I salt determined by X-ray fiber diffraction
| Autor: | Keiichi Noguchi, Amornrat Lertworasirikul, Shingo Yokoyama, Kenji Okuyama, Kozo Ogawa |
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| Rok vydání: | 2004 |
| Předmět: |
Models
Molecular Static Electricity Iodide Chitin Crystal structure Crystallography X-Ray Biochemistry Analytical Chemistry X-Ray Diffraction Carbohydrate Conformation Animals Fiber chemistry.chemical_classification Chitosan Hydrogen bond Organic Chemistry Hydrogen Bonding General Medicine Polymer Crystallography chemistry X-ray crystallography Salts Crystallization Fiber diffraction Monoclinic crystal system |
| Zdroj: | Carbohydrate Research. 339:825-833 |
| ISSN: | 0008-6215 |
| DOI: | 10.1016/j.carres.2004.01.001 |
| Popis: | The three-dimensional structure of chitosan/HI type I salt was determined by the X-ray fiber diffraction technique and linked-atom least-squares refinement method. Two polymer chains and four iodide ions (I(-)) crystallized in a monoclinic unit cell with dimensions a = 9.46(2), b = 9.79(2)], c (fiber axis)=10.33(2)A, beta = 105.2(2) degrees and a space group P2(1). Chitosan chains adopted an extended twofold helical conformation that was stabilized by O-3...O-5 hydrogen bonds, and the O-6 atom adopted nearly gt orientation. Polymer chains zigzag along the b-axis and directly connect to each other by N-2...O-6 hydrogen bonds. Two columns of iodide ions were shown to pack at the bending points of the zigzag sheets, and their locations are closely related to those of water columns in the hydrated chitosan. The iodide ions stabilized the salt structure by forming hydrogen bonds with the N-2 and O-6 atoms of the polymer chains together with an electrostatic interaction between N-2 and the iodide ions. |
| Databáze: | OpenAIRE |
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