Cellobiose as a model system to reveal cellulose dissolution mechanism in acetate-based ionic liquids: Density functional theory study substantiated by NMR spectra.
Cellulose dissolution mechanism in acetate-based ionic liquids was systematically studied in Nuclear Magnetic Resonance (NMR) spectra and Density Functional Theory (DFT) methods by using cellobiose and 1-butyl-3-methylimidazolium acetate (BmimAc) as a model system. The solubility of cellulose in ionic liquid increased with temperature increase in the range of 90-140°C. NMR spectra suggested OAc(-) preferred to form stronger hydrogen bonds with hydrogen of hydroxyl in cellulose. Electrostatic potential method was employed to predict the most possible reaction sites and locate the most stable configuration. Atoms in molecules (AIM) theory was used to study the features of bonds at bond critical points and the variations of bond types. Simultaneously, noncovalent interactions were characterized and visualized by employing reduced density gradient analysis combined with Visual Molecular Dynamics (VMD) program. Natural bond orbital (NBO) theory was applied to study the noncovalent nature and characterize the orbital interactions between cellobiose and Bmim[OAc].
School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165, China. Electronic address: qufucaobobo@163.com.
Bobo
B
Cao
School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165, China. Electronic address: jwyhbxr@163.com.
Jiuyao
J
Du
School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165, China. Electronic address: dongmei1969@163.com.
Dongmei
D
Du
School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165, China. Electronic address: sunhaitao1960@126.com.
Haitao
H
Sun
School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165, China. Electronic address: qfnu_zx@163.com.
Xiao
X
Zhu
College of Science, China University of Petroleum, Qingdao, Shandong 266580, China. Electronic address: fuhui@upc.edu.cn.
Hui
H
Fu
D000085:Acetates / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002475:Cellobiose / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory
D000085:Acetates; D052578:Ionic Liquids; D002475:Cellobiose; D002482:Cellulose
Cellulose; DFT; Dissolution mechanism; Hydrogen bond; Ionic liquid; NMR spectra