New amphoteric chelating/ion exchange resins with substituted carbamylethylenephosphonates; synthesis and EPR studies of their Cu(II) complexes

Two new chelating/ion-exchange resins have been obtained by amination of vi nylbenzyl chloride-styrene-divinylbenzene copolymer, bearing ethoxycarbonyl ethyl phosphonate, with ethylenediamine and diethylenetriamine. The effect of close proximity of acidic and basic sites of ligand on chelating/ion-exc hange of four divalent metal cations has been studied. In order to explain the behavior of the synthesized resins, a series of reference resins has be en obtained. These resins have same types of functional groups--phosphonic acid and N-substituted amide of carboxylic acid but deposited randomly with in polymer material. It has been found that close proximity of both acidic and basic sites, interacting with each other, gave antagonistic effect at p H 3.7 and 5.6 and suppressed uptake of Cu(II), Cd(II), Ni(II) and Zn(II) fr om weakly acidic solutions. For example Resins 1 and 2 with carbamylethylen ephosphonates displayed at pH 3.7 log K-d CU(II) 2.10 and 3.06, whereas ref erence Resins 3 and 4 had log K-d Cu(II) 2.83 and 4.50, respectively. EPR s tudies of Cu(II) complexes formed in each case were used to explain the obs erved effect. (C) 2000 Elsevier Science Ltd. All rights reserved.