Molecular Architecture of Softwood Revealed by Solid-State NMR
The molecular arrangement and interactions of lignin and polysaccharides in plant secondary cell walls are generally poorly understood due to technical difficulties of analysing this complex material which is made primarily out of the polysaccharides cellulose, xylan and galactoglucomannan and the polyphenolic polymer lignin.
The results of a multidimensional solid-state NMR show that lignin is associated with both xylan, galactoglucomannan and surface chains of cellulose. Xylan and Galactoglucomannan bind to the same cellulose microfibrils. Some lignin is close to hemicelluloses and cellulose. Whereas covalent linkages may mediate such proximity between the two, this feature cannot be firmly established are the sensitivity of these solid-state NMR experiments is not yet high enough to identify such rare events.