Article

Projet
 
Denis WOUESSIDJEWE, Luc CHOISNARD,   
Titre
Single Crystals of V-Amylose Complexed with Bicyclic Organic Compounds. Special Issue: Polymer‐Solvent Complexes and Intercalates  
[Full paper ]
Auteurs
Cong‐Anh‐Khanh Le Luc Choisnard Denis Wouessidjewe Jean‐Luc Putaux
Pages
1-7
Tome
386
Collection
Macromolecular Symposia - Electron Crystallography
Editeurs
WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Edition
MACROMOLECULAR SYMPOSIA
Année
2019
Résumé
Lamellar single crystals of V-amylose were prepared from dilute aqueous solutions in the presence of selected bicyclic compounds. Transmission electron microscopy images as well as electron and X-ray diffraction patterns revealed that two allomorphs containing 7-fold amylose single helices were formed depending on the complexing agent. On the one hand, trans-decalin and (-)-beta-pinene induced the crystallization of an orthorhombic unit cell isomorphous to that of V2-propanol crystals reported in the literature (referred to as V7(II)). On the other hand, (+)-camphor and (-)-borneol yielded a new compact pseudo-hexagonal structure (referred to as V7(I)). Cis-decahydro-1-naphthol and decahydro-2-naphthol induced the formation of both allomorphs. V7(I) was favored at a higher crystallization temperature compared to V7(II). Upon drying in vacuum, both V7(I) and V7(II) converted into the hexagonal anhydrous allomorph V7(a) but the initial structures were recovered by rewetting the crystals in water at room temperature. In addition, washing the crystals with methanol resulted in a transition from a 7-fold to a 6-fold helical conformation of amylose. The results suggest that both water and complexing agent play an important role on the formation and stability of V-amylose crystals.