Binding, electrochemical and metal extraction properties of the new redox-active polyazacycloalkane 1,4,7,10,13,16-hexa-(ferrocenylmethyl)-1,4,7,10,13,16-hexaazacyclooctadecane

The redox-functionalised polyazacycloalkane receptor 1,4,7,10,13,16-hexa(ferrocenylmethyl)-1,4,7,10,13,16-hexaazacyclooctadecane (L-1) has been designed and synthesized and its binding, electrochemical and metal extraction properties studied. The results have been compared to those obtained for the parent redox-active polyazacycloalkane 1,4,8,11-tetra(ferrocenylmethyl)-1,4,8,11-tetraazacyclotetradecane, L-3. The cadmium complex of L-1 and the free receptor L-3 have been crystallographically characterised. The structure of [CdL1][PF6](2). 4CH(3)CN . 4H(2)O consists of cationic [CdL1](2+) units in which the cadmium ion exhibits a distorted octahedral environment. Solution studies by potentiometric methods have also been carried out in the presence of H+ and Cu2+ in 1,4-dioxane-water (70:30 v/v, 25 degrees C, 0.1 mol dm(-3) KNO3) for L-1 and thf-water (70:30 v/v, 25 degrees C, 0.1 mol dm(-3) [NBu4n][ClO4]) for L-3. Electrochemical experiments as a function of the pH in the presence of Ni2+, Cu2+, Zn2+, Cd2+ or Pb2+ have been carried out for L-1 and L-3. The solvent extraction properties of L-1 have also been studied.