Molecular Modeling of Selectivity of Ortho-ester Tetra Azophenylcalix[4]arene for Metal Ions

The tetra azophenylcalix[4]arene with ortho-ester group was applied for determination of transition metal ions using spectrophotometer. In this case, the derivatives with ortho-ester group turned out the complexing formation selectively with transition metal ions over alkali, alkaline earth metal ions. From those, this study used the molecular mechanic method MM+ and molecular dynamic simulation, semi-empirical quantum chemical calculations (SCF AM1, PM3 and ZINDO/S) to investigate the complexes formation of metal ions with ortho-ester tetra azophenylcalix[4]arene. The complexes of ortho-ester tetra azophenylcalix[4]arene and metal ions Na+, K+, Ca2+, Mg2+, Co2+, Ni2+ and Cu2+ in 265 complexes in water molecules were simulated by combining molecular mechanics (MM+) with molecular dynamic simulation (MD). The investigated structures in this work pointed out the different insight of the superior selectivity of ortho-ester tetra azophenylcalix[4]arene for metal ions. The stability constants of complexes host-Mn+ correlated closely with the relative energies of them. The binding energies of those represented the stable characteristics of ortho-ester tetra azophenylcalix[4]arene with metal ions.