Molecular design of a novel ligand for Menshutkin complexation of Bi(III) from aqueous acidic copper sulfate electrolyte solutions and experimental investigations

5-Amino-2,9-diphenoxy-1,10-phenanthroline functionalized silica is designed to reversibly adsorb bismuth impurities from strongly acidic aqueous copper sulfate solutions. The ligand interacts with Bi(III) ions through weak non-covalent interactions due to the presence of the arene-pi electron cloud of the phenyl moiety. The stronger complexation of Bi(III) as compared to Sb(III), As(III) and Cu(II) ions with the ligand was explored using Density Functional Theory (DFT) under solvated conditions. The theoretical predictions were validated by experimental studies with Bi(III)/Cu(II) mixtures in aqueous acidic solutions. The ligand shows very high selectivity (alpha = 978) towards Bi(III) in the presence of a high concentration of Cu(II) in the acidic solutions.