title: Hydrogen-Bonding Network and OH Stretch Vibration of Cellulose: Comparison of Computational Modeling with Polarized IR and SFG Spectra.
abstract: Hydrogen bonds play critical roles in noncovalent directional interactions determining the crystal structure of cellulose. Although diffraction studies accurately determined the coordinates of carbon and oxygen atoms in crystalline cellulose, the structural information on hydrogen atoms involved in hydrogen-bonding is still elusive. This could be complemented by vibrational spectroscopy; but the assignment of the OH stretch peaks has been controversial. In this study, we performed calculations using density functional theory with dispersion corrections (DFT-D2) for the cellulose Iβ crystal lattices with the experimentally determined carbon and oxygen coordinates. DFT-D2 calculations revealed that the OH stretch vibrations of cellulose are highly coupled and delocalized through intra- and interchain hydrogen bonds involving all OH groups in the crystal. Additionally, molecular dynamics (MD) simulations of a single cellulose microfibril showed that the conformations of OH groups exposed at the microfibril surface are not well-defined. Comparison of the computation results with the experimentally determined IR dichroism of uniaxially aligned cellulose microfibrils and the peak positions of various cellulose crystals allowed unambiguous identification of OH stretch modes observed in the vibrational spectra of cellulose.
authors.affiliation: Department of Chemical Engineering and Materials Research Institute, The Pennsylvania State University , University Park, Pennsylvania United States.|Center for Lignocellulose Structure and Formation, The Pennsylvania State University , University Park, Pennsylvania United States.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Lee
authors.affiliation: Department of Geological Sciences, University of Texas at El Paso , El Paso, Texas 79968, United States.|Center for Lignocellulose Structure and Formation, The Pennsylvania State University , University Park, Pennsylvania United States.
authors.forename: James D
authors.initials: JD
authors.lastname: Kubicki
authors.affiliation: Department of Chemical Engineering and Materials Research Institute, The Pennsylvania State University , University Park, Pennsylvania United States.|Center for Lignocellulose Structure and Formation, The Pennsylvania State University , University Park, Pennsylvania United States.
authors.forename: Bingxin
authors.initials: B
authors.lastname: Fan
authors.affiliation: Department of Chemistry, The Pennsylvania State University , Mont Alto, Pennsylvania 17237, United States.|Center for Lignocellulose Structure and Formation, The Pennsylvania State University , University Park, Pennsylvania United States.
authors.forename: Linghao
authors.initials: L
authors.lastname: Zhong
authors.affiliation: School of Chemistry, University of Glasgow , Glasgow G12 8QQ, Scotland, U.K.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Jarvis
authors.affiliation: Department of Chemical Engineering and Materials Research Institute, The Pennsylvania State University , University Park, Pennsylvania United States.|Center for Lignocellulose Structure and Formation, The Pennsylvania State University , University Park, Pennsylvania United States.
authors.forename: Seong H
authors.initials: SH
authors.lastname: Kim
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D006860:Hydrogen Bonding; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002482:Cellulose