CP/MAS ¹³C NMR Study of Cellulose and Cellulose Derivatives. 2. Complete Assignment of the ¹³C Resonance for the Ring Carbons of Cellulose Triacetate Polymorphs

Abstract

Complex ring (13)C resonance lines of the cross-polarization/magic angle spinning (CP/MAS) (13)C NMR spectra of cellulose triacetate (CTA) I and CTA II were completely assigned, for the first time, by (13)C-enriched CTA allomorphs. The (13)C-enriched CTA I was prepared by heterogeneous acetylation of bacterial cellulose which was biosynthesized by Acetobacter xylinum (A. xylinum) ATCC10245 from culture medium containing D-(2-(13)C)-, D-(3-(13)C)-, or D-(5-(13)C)glucose as a carbon source, while CTA II samples were obtained by solution acetylation of the (13)C-enriched bacterial celluloses. From comparison of the spectra of normal CTA prepared from ramie with those of the enriched CTA samples, it was revealed that all carbons composed of CTA I appeared as a singlet, while those of CTA II except for C1 were shown as equal-intensity doublets in the CP/MAS (13)C NMR spectrum. This finding suggests that CTA I is made up of one kind of glucopyranose residue while there are two magnetically inequivalent sites in the unit cell of CTA II in the same population.

Two‐dimensional magic angle spinning NMR investigation of naturally occurring chitins: Precise 1H and 13C resonance assignment of α‐ and β‐chitin

“…Recently, we applied INADEQUATE and MAS-J-HMQC NMR techniques to 13 C-enriched CTA I and CTA II for the elucidation of the crystal structures of both allomorphs. 22,43 As a result, it was revealed that the numbers of respective 13 C and 1 H shifts of CTA I agreed with the those of the 2,3,6-triacetyl-anhydroglucopyranose residue in the allomorph, strongly suggesting that the asymmetric unit of CTA I is only one residue. On the other hand, it was revealed that the CP/MAS 13 C NMR spectrum of CTA II was characterized by its overlapping of the 13 C subspectra of two kinds of 2,3,6-triacetyl-anhydroglucopyranose monomer units and that there are two magnetically nonequivalent sites in the unit cell of CTA II.…”

FT Raman spectroscopic investigation of cellulose acetate

“…The structure of CTA has been analysed with 1 H, 13 C, CP/ MAS 13 C and 2-dimentional NMR with assignment of the signals ascribed to the corresponding protons or carbons within CTA (Dais and Perlin 1988;Goodlett et al 1971;Kono et al 2002;Miyamoto et al 1984). Investigations with solid-state 13 C NMR spectroscopy or 2-dimentional solid state 13 C-13 C and 1 H-13 C correlation NMR spectroscopy allowed the analysis of crystalline allomorphs-CTAI and CTAII (Kono et al 2002;Kono et al 2004;VanderHart et al 1996). Recently, cellulose diacetate has been analysed by 2-dimentional infrared correlation spectroscopy and the structural features of the hydrogen-bond system induced by heating were investigated (Guo and Wu 2008).…”

Radially oriented cellulose triacetate chains on gold nanoparticles

“…From a fundamental aspect, there have been some reports on crystalline polymorphs of cellulose and cellulose triacetate (CTA) (Kono et al 1999(Kono et al , 2002. Both cellulose I and CTA I are accepted to have parallel orientation (Stipanovic and Sarko 1978;Sugiyama et al 1991;Woodcock and Sarko 1980).…”