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

Abstract

AbstractChelate 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.