Synthesis of schiff bases with 2-aminothiophenol and dialdehyde, synthesis and characterization of their complexes with transition metals and extraction applications

In this study, new thio Schiff bases, N,N?-bis(2-aminothiophenol)-1,4- bis(carboxylidene phenoxy)butane (L1) and N,N?-bis(2-aminothiophenol)-1,7- bis(formylphenyl)-1,4,7-trioksaheptane (L2) were synthesized. Cu(II), Ni(II), Zn(II), Co(II) and La(III) complexes with Schiff bases were prepared. The structure of the ligands and their complexes were determined by FTIR, elemental analyses, magnetic susseptibility, conductance measurements, 1H-NMR, 13C-NMR and cyclic voltammetry. There were investigated the extraction of copper(II) and nikel(II) ions from aqueous phase to organic phase with the synthesized ligands. In the first step, the effect of time on ligand and metal ions extractions were investigated. 15, 30, 45, 60 and 120 minutes were chosen in order to study the effect of time on extraction. After the extraction process the concentrations of metal ions left in aqueous phase were measured by AAS and the percentages of metal was calculated. In the second step, in order to investigate the effect of pH on the extraction of metal ions with L1 and L2 ligand, the aqueous phase of pH was changed between 3-10. To keep the medium pH constant during the extraction time acetic acid-sodium acetate and sodium carbonate-sodium bicarbonate buffer solutions were used. After the extraction process the concentrations of metal ions left in aqueous phase were measured by AAS the percentages of extracted Cu(II) and Ni(II) were calculated. By using equation (page 45) which was obtained from the extraction experiments the log H2L value was plotted against log D and linear line was obtained. The combination ratio was calculated from slope. The log Kext constant was obtained from the shift value. Key words : 2-aminothiophenol, thio Schiff bases, thio Schiff base complexes, solvent extraction, electronic transitions, cyclic voltammetry.