Faster magic angle spinning reveals cellulose conformations in woods.

Area of Science:

• Biomolecular Chemistry
• Materials Science
• Spectroscopy

Background:

• Cellulose, a key biopolymer, exhibits diverse structural conformations influencing its properties.
• Understanding cellulose structure in natural materials like wood is crucial for material science and biomass utilization.
• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool for characterizing complex biopolymers.

Purpose of the Study:

• To report the first detection of three distinct C6 conformers of cellulose in spruce wood.
• To investigate the impact of thermal treatment on the structural order of cellulose fibrils in spruce.
• To advance solid-state NMR techniques for analyzing natural cellulose samples.

Main Methods:

• Utilized high-resolution solid-state 1H-13C correlation spectroscopy with 150 kHz magic-angle spinning.
• Employed proton (1H) decoupling to suppress the dense dipolar network, enhancing spectral sensitivity.
• Analyzed inverse-detected 13C spectra of natural spruce samples.

Main Results:

• Successfully identified three different C6 conformers of cellulose in spruce.
• Observed initially higher ordering of glycosidic linkages in spruce cellulose compared to maple.
• Demonstrated that thermal treatment of spruce leads to a more heterogeneous packing order of cellulose fibrils.

Conclusions:

• The study provides novel insights into the structural diversity of cellulose in spruce wood.
• Advanced solid-state NMR techniques enable detailed characterization of cellulose conformations in natural matrices.
• Thermal processing significantly influences the structural organization and packing of cellulose fibrils in spruce, with implications for wood properties and applications.