Macrocyclic Polyether Tetralactams II : A Study of their Binding Properties with Alkaline - Earth Cations

Article abstract of DOI:10.1016/S0040-4020(01)80445-2

Solvent extractions of alkali and alkaline-earth picrates were carried out in a water-chloroform system using newly synthesized tetralactams containing dimethyleneoxy moieties.These ligands display excellent extracting properties for Ca²⁺, Ba²⁺ and Sr²⁺ cations.Some of the less lipophilic derivatives have greater preference for Ba²⁺ vs.Na⁺ and Zn²⁺ and, to a lesser extent, K⁺, Mg²⁺ and Ca²⁺.In addition, the stability constants were determined for the 1:1 and the 1:2 M²⁺:tetralactam complex by UV spectrophotometry in THF solution.In each series of tetralactams log K_S values as high as 6 were observed for Ca²⁺, Sr²⁺ and Ba²⁺ ions.The 18-, 21- and 24-membered tetralactams complex preferentially Sr²⁺, Ca²⁺ and Ba²⁺ cations respectively.Keywords: Tetralactam; Complexation; Stability Constants; Liquid-Liquid-Extraction; Alkaline-Earth Cations