QSPR of the extraction equilibrium constants of Cu(II), Zn(II) and Co(II) with 8-sulfonamidoquinolines

The extraction mechanism of Cu(II), Zn(II) and Co(II) with 8-sulfonamidoqui nolines was investigated using semi-empirical molecular orbital calculation s. From the calculated results, it was found that the optimized geometries of alkyl-substituted 8-sulfonamidoquinolines (henceforth CnSAQ) nearly agreed with those of p-alkylphenyl-substituted 8-sulfonamidoquinolines (henceforth CnphSAQ). In particular, there was no remarkable change in the geometries of the coordination site and dipole moments of the extractants. A quantitat ive structure property relationship (QSPR) was developed from the correlati on of the calculated heats of formation for metal complex formation and the relative extractability. The difference in extraction equilibrium constant s between CnSAQ and CnphSAQ could be attributed to the effect of the hydrop hobicity of the phenylene group of CnphSAQ.