Immobilized β-Cyclodextrins. Preparation with Various Crosslinking Reagents and the Guest Binding Properties

Abstract β-Cyclodextrin (β-CyD) was immobilized by crosslinking with 1,2-ethanediol diglycidyl ether, 1,4-buthanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,3-butadiene diepoxide, 1,7-octadiene diepoxide, and epichlorohydrin. The molar ratio of the crosslinking residue to β-CyD (degree of crosslinking) for each macromolecular product was determined by the corresponding elemental analysis. The equilibrium constant K of complex formation of each crosslinking macromolecule for cresols, phenol, nitrophenols, and 2-naphthol was determined, respectively, by the use of electronic absorption spectroscopy in pH 4 and 10 (or 11) buffer solutions. The concept of a hydrophobic enhancement coefficient R was introduced in order to compare the effect of a hydrophobic crosslinking residue upon the complex formation of the immobilized CyD.