Interaction between thallium(III) bromide and dicyclohexano-18-crown-6 immobilized on silica

The adsorption of cis-syn-cis-dicyclohexano-18-crown-6 on silica gel from organic solvents was studied. In the adsorption from chloroform solutions, the immobilization of the reagent molecules at the surface was coplanar. Hydrogen bonds between surface silanol groups and oxygen atoms of the polyether ring of the crown ether play an important role in the immobilization of the reagent. The reaction between thallium(III) bromide and the immobilized reagent was studied. The composition of complex compounds formed at the surface of the modified adsorbent was found. A procedure was proposed for the sorption-spectrophotometric determination of thallium(III) (≥0.05 mg/L) in the presence of heavy metal ions.