Interactions of Cellulose Model Compound D-Cellobiose with Selected Metal Chlorides in Water: Identification of Chelating Oxygen Atoms

Understanding interactions of metal ions with cellulose is an important step in the development of efficient catalytic methods for processing cellulose. In this study, density functional theory methods were used to identify oxygen atoms interacting or chelating with selected metal chlorides of Li+, K+, Mg2+, Ca2+, Sn2+, Zn2+ and La3+ with cellulose model compound D-cellobiose. Calculated metal-oxygen distances of energy minimized D-cellobiose : metal chloride 1 : 2 mixtures revealed that the metal ions approach between the two glucose rings in alpha/beta-D-cellobiose, and O-4, O-9 are the preferred interaction/chelation points. DFT study supported a previous C-13 NMR chemical shift change based experiments. ZnCl2 showing the shortest metal-oxygen distances in approach to alpha/beta D-cellobiose is known to produce the largest C-13 NMR chemical shift changes in D-cellobiose. In alpha-anomer, average closest metal-oxygen distances and NMR shift changes co-related at 95 % confidence interval with liner regression R-2=0.8582 and Sy.x=0.5722.

Automated summary

Understanding interactions of metal ions with cellulose is crucial for developing efficient catalytic methods. This study used density functional theory to investigate metal-oxygen distances and found that ZnCl2 showed the shortest distance and the largest C-13 NMR chemical shift changes in D-cellobiose. Additionally, the study revealed specific preferred interaction points for metal ions in cellulose model compounds.