13C and 1H Resonance Assignment of Mercerized Cellulose II by Two-Dimensional MAS NMR Spectroscopies

Through-bond 13C−13C and 13C−1H correlations in the crystal structure of cellulose II were determined by the two-dimensional (2D) refocused INADEQUATE and MAS-J-HMQC spectra of the mercerized cellulose, which was biosynthesized by Acetobacter xylinum ATCC 10245 from the uniformly labeled glucose (d-(U-13C6)glucose). Mercerization of the bacterial cellulose was achieved in a solution of 20% NaOH in water for 2 weeks. In the 2D INADEQUATE spectrum of cellulose II, two sets of the through-bond 13C−13C connectivities from C1 through C6 were clearly observed, which enabled us to completely assign the complex 1D CP/MAS 13C spectrum of cellulose II. Following the 13C assignment, the 1H resonance for the proton(s) attached to each carbon of cellulose II could be assigned by use of the 2D MAS-J-HMQC spectrum of the mercerized cellulose.