A comparative study of the metal binding behavior of alanine based bis-thiourea isomers

Abstract

Two new symmetrical bis-thiourea, 2,2′-[{(terephthaloylbis(azanediyl)bis(carbonothioyl) bis(azanediyl)}dipropanoic acid] (1A) and 3,3′-[{(terephthaloylbis(azanediyl)bis (carbonothioyl)bis(azanediyl)} dipropanoic acid] (1B) were synthesized by the reaction of terephthaloyl chloride with α- and β-alanine in good yields. Their binding properties were investigated with various metal cations using UV–Vis titration experiments. Both isomers exhibited effective binding with Ag⁺, Cu²⁺, Hg²⁺, Pb²⁺, Fe²⁺ and Fe³⁺ cations. However, in the presence of other cations, such as Na⁺, Ni²⁺, Co²⁺, Cd²⁺, Zn²⁺, Mn²⁺, Mg²⁺, Ca²⁺, Sn²⁺, Al³⁺, and anions tetrabutylammonium Cl⁻ and H₂PO₄⁻, no interaction occurred. Both isomers displayed similar trends towards binding with metal cations.