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Single Crystals of V‐Amylose Complexed with Bicyclic Organic Compounds
Author(s) -
Le CongAnhKhanh,
Choisnard Luc,
Wouessidjewe Denis,
Putaux JeanLuc
Publication year - 2019
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.201900007
Subject(s) - crystallography , crystallization , anhydrous , amylose , orthorhombic crystal system , chemistry , bicyclic molecule , lamellar structure , transmission electron microscopy , materials science , stereochemistry , crystal structure , organic chemistry , nanotechnology , starch
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 (−)‐β‐pinene induced the crystallization of an orthorhombic unit cell isomorphous to that of V 2‐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.