Structure of a cellulose I–ethylenediamine complex

Abstract

44106 SynopsisThe structure of a crystalline cellulose I-ethylenediamine complex has been determined by x-ray diffraction methods as part of an investigation of cellulose-solvent interaction. The complex studied is that formed when native ramie fibers are swollen in ethylenediamine and then vacuum-dried. The unit cell is monoclinic with dimensions a = 12.87 A, b = 9.52 A, c = 10.35 A, and y = 118.8", and it contains disaccharide segments of two chains, with one ethylenediamine per glucose residue. The refined model contains parallel cellulose chains that are linked by hydrogen-bonded ethylenediamine molecules. The chains along the b-axis are packed in register, leading to stacks of chains analogous to those in chitin. All the hydroxyl groups are satisfactorily hydrogen-bonded and each ethylenediamine forms four donor and two acceptor hydrogen bonds. From this work it can be seen that the interaction of cellulose I with ethylenediamine involves scission of the intermolecular hydrogen bonds followed by disruption of the stacks of quarter-staggered chains.

The structure of the complex of cellulose I with ethylenediamine by X-ray crystallography and cross-polarization/magic angle spinning 13C nuclear magnetic resonance

“…The new structure is significantly different from the previously reported X-ray structure (Lee et al 1984) and provides new insights into the structural pathway followed during the solid-state conversion of cellulose by EDA. The structure also reveals similarities and differences in the detailed action of ammonia and EDA on cellulose.…”

“…Detailed crystal structures for the cellulose I a , I b , III I phases in this pathway have already been provided (Nishiyama et al 2002(Nishiyama et al , 2003Wada et al 2001Wada et al , 2004. A crystal structure has also been reported for EDA-cellulose I from X-ray diffraction studies (Lee et al 1984), however recent cross-polarization/magic angle spinning (CP/MAS) 13 C nuclear magnetic resonance (NMR) studies have raised doubts about the details of this structure (Numata et al 2003).…”

“…However, a fitting analysis resulted in only one EDA molecule per two Fig. 1 The solid-state conversion of cellulose between various crystal phases involving EDA and hydrothermal treatment glucosyl residues, in disagreement with the X-ray structure (Lee et al 1984).…”

“…A preliminary analysis of the X-ray reflection positions in this data resulted in a new unit cell (space group P2 1 ; a = 4.55 Å , b = 11.33 Å , c = 10.37 Å and c = 94.02°) with a volume that is about half of that proposed in previous X-ray crystallographic studies (Lee et al 1984). Although no crystal structure determination was carried out, on the basis of unit cell size, density measurements, and thermogravimetric analysis we were able to determine that this unit cell corresponds to one cellulose chain, with the asymmetric unit composed of one glucosyl residue and one EDA molecule.…”

“…More extensive X-ray diffraction data collected from ramie fibers treated with EDA allowed the determination of a more detailed structure; two parallel chains pack in a monoclinic unit cell with P2 1 symmetry (a = 12.87 Å , b = 9.52 Å , c = 10.35 Å , c = 118.8°) (Lee et al 1984). The two, almost identical, independent chains have the same translation along the chain (c-axis) direction and lie on 2-fold screw axes.…”