On cellulose spatial organization and interactions as unraveled by diffraction and spectroscopic methods throughout the 20th century

Abstract

Abstract This contribution attempts to describe the path towards determination of cellulose crystal structure down to atomic coordinates, towards the determination of its molecular conformation, as well as towards the details of the intricate pattern of hydrogen bonds and their dynamics. This path started at the beginning of the 20th century with X-ray diffraction, continued with electron diffraction, infrared and Raman spectroscopy, and significant knowledge was gained by methods of NMR spectroscopy. Towards the end of the 20th century and at the beginning of the 21st century, X-ray diffraction in conjunction with neutron diffraction provided the position of hydrogens, which led to detailed description of the geometry of hydrogen bonding network in cellulose. Quantum chemical and molecular dynamics calculations, polarized infrared spectroscopy and sum frequency generation vibrational spectroscopy were used to identify the origins of the vibrational modes in cellulose and to describe their extensive coupling mediated by hydrogen bonds. The role of amphiphilic character of cellulose macromolecule (and consequent hydrophobic interactions) in cellulose properties and behavior has been gaining more recognition in the 21st century.