Reactive & Functional Polymers, Vol.39, No.1, 27-35, 1999
Syntheses and characterization of a chelating resin containing ONNO donor quadridentate Schiff base and its coordination complexes with copper(II), nickel(II), cobalt(II), iron(III), zinc(II), cadmium(II), molybdenum(VI) and uranium(VI)
A new mixed Schiff base N,N'-ethylenemono(3-carboxysalicylideneimine)mono(salicylideneimine) has been synthesized by the condensation of equimolar quantities of ethylenediamine, salicylaldehyde and 3-formylsalicylic acid. A polymer supported Schiff base (PS-CH2-LH2) has been synthesized by the reaction of chloromethylated polystyrene (containing 3.9 mmol of chlorine per g of resin and 2% cross-linked with divinylbenzone) and the Schiff base N,N'-ethylenemono(3-carboxysalicylideneimine)mono(salicylideneimine). The polymer-anchored Schiff base reacts with metal salt/metal complex and forms polymer-anchored complexes having the formulae PS-CH2-LCu, PS-CH2-LNI, PS-CH2-LCo, PS-CH2-LFeCl . DMF, PS-CH2-LZn, PS-CH2-LCd, PS-CH2-LMoO2 and PS-CH2-LUO2. The polymer-anchored complexes have been characterized on the basis of elemental analysis, infrared and electronic spectra and magnetic susceptibility measurements. The shifts of the nu(C=N) (azomethine) stretch to lower energy and nu(C=O) (carboxylic) to higher energy in the polymer-anchored complexes indicate the ONNO donor behaviour of the chelating resin. The metal ions in the metal bound polymers can be leached by hot dilute formic acid, acetic acid or hydrochloric acid. The coordinated dimethylformamidc is completely lost on heating the complexes in air. The complexes PS-CH2-LCu and PS-CH2-LCo are paramagnetic with square planar structure, PS-CH2-LNi is diamagnetic with square planar structure and PS-CH2-LFeCl . DMF is paramagnetic and octahedral, PS-CH2-LZn and PS-CH2-LCd are diamagnetic and tetrahedral, PS-CH2-LMoO2 and PS-CH,-LUO, are diamagnetic and have octahedral structure. The stoichiometry and the structure of the metal bound polymers are comparable with those of metal complexes of N,N' -ethylenebis(salicylideneimine). This is the first report of the syntheses of a mixed Schiff base and its coordination complexes.