Selective adsorption of metal ions on poly(4‐vinylpyridine) resins in which the ligand chain is immobilized by crosslinking

Abstract Chelate forming resins ( 3 ) were prepared by crosslinking poly(4‐vinylpyridine) ( 1 ) with 1,4‐dibromobutane ( 2 ) and their complexation with metal ions was studied. Stability constants ( K ) were found to be much higher for the Cu‐ 3 system than for the Cu‐ 1 system, which indicates that 3 uptakes Cu ions with high efficiency. K and the adsorption capacity of Cu decrease largely with increasing degree of crosslinking. Visible and ESR spectra of Cu‐ 3 show that the structure of the Cu complex within 3 is the same as that of the monomeric Cu‐pyridine complex. However, the ligand‐chain is immobilized in the highly crosslinked 3c and 3d , so that the square planar structure of a stable Cu complex is distorted. The amount of adsorption of Cu, Fe, Cr, Ni, and Zn ions on 3 decreases with the crosslinking, but the adsorption of Hg ions is independent; i.e. 3d selectively adsorbs Hg ions. Metal complexed 1 was crosslinked according to Scheme 1 and the metal ion which was used as template is well adsorbed by the obtained 3 . It is considered, therefore, that the ligand chain is maintained at the best conformation for the template ion.