(400c) Thermodynamics of Lignin Dimers and ?-Cyclodextrin Complexes
Understanding the interactions of lignin-derived small molecules with CDs in solution will support our efforts to create selective immobilized CD-MSNPs, whose binding with small molecules can also be quantified with isothermal titration calorimetry (ITC). The present work aims to study binding of Î²-CD to three types of lignin dimers including two derivatives of Î²O4â dimers of coniferyl alcohol (GG lignin dimer) as well as pinoresinol (G-Î²Î²-G) using ITC. The equilibrium binding constant (K) and the thermodynamic binding energies (ÎH, ÎS, and ÎG) for dimer-Î²-CD complexes are determined from fitting binding models to the ITC data. The results of this work show that guiacylglycerol guaiacol ester with a hydroxypropenyl (HOC3H4-) tail (G-Î²O4â-G) binds to the Î²-CD through a different mechanism than pinoresinol and commercially available guaiacylglycerol-Î²-guaiacyl ether (G-Î²O4â-truncG) lignin dimer. The results for the G-Î²O4'-G are in good agreement with molecular simulations conducted for the same system. We also demonstrate that CD-lignin interactions can be used to develop selective separation strategies for lignin-derived small molecules, and investigated the surface modification techniques to attach Î²-CD directly to the silica MSNPs, with a goal of using the silica particles for selective capture of lignin-derived small molecules.