Synthesis and properties of supramolecular systems based on silica.

The synthesis of mono-tosyl-beta-cyclodextrin (Ts-beta-CD) and its attachment to the surface of aminopropylsilica are reported. The resulting material was characterized by IR spectroscopy, elemental analysis, and quantitative evaluation of the surface compounds. The maximum amount of beta-cyclodextrin (beta-CD) grafted on the surface of silica was 60% of the computer-calculated value. The uptake of Cu(II), Cd(II), and Pb(II) ions by this modified material as a function of the pH and salt concentration in the aqueous phase was investigated. It is shown that the silica modified with beta-CD has a much greater capacity to uptake these ions than the starting materials. The formation of grafted inclusion compounds of beta-cyclodextrin molecules with polymeric hydroxo complexes of metal cations is demonstrated.