Synthetis and ion selective properties of benzothiazolylacetamidoalkoxycalix[4]arene for copper(II) ion

Novel ligands 15-18 consisting of benzothiazolylacetamidoalkoxy moiety organized on the narrow rim of calix[4]arene platform were synthesized. The interaction of the ligand with metal ions was studied by UV-vis spectroscopy. Among the metal ions studied, only Cu²⁺, Ni²⁺, and Hg²⁺ caused significant change of the ligand spectrum while Na⁺, K⁺, Ca²⁺, Mg²⁺, Pb²⁺, Cd²⁺ caused very small change of ligand spectra. The stability constant for a 1:1 complexation was determined by fitting the UV-vis titration data with the computer program. The logarithm of stability constant of metal complexes are 3.8-4.1 for copper complexes, 3.3-4.0 for mercury complexes and 2.3-2.8 for nickel complexes. A preliminary evaluation of Cu²⁺ ion-selective membranes made from the ligands was done using a membrane composition of 1.0: 65.6: 33.0: 0.40 (ligand: 0-NPOE: PVC: KTCIPB in weight percent). The electrode responses were 21.3 - 26.8 mV decade⁻¹at 25°C. The logarithm of potentiometric selectivity coefficient (log Ko[subscript pol] [subscript Cu²⁺], j, FIM) were -1.59 to -2.29 (Ca²⁺), -1.59 to -2.29 (Mg²⁺), -0.95 to -1.40 (Cd²⁺), -0.95 to -1.35 (Ni²⁺), -0.40 to 0.10 (Na⁺), -0.30 to 0.35 (K⁺) and -0.27 to 0.28 (Pb²⁺).