Ferrocene-appended and bridged calixareneligands for the electrochemical sensing of trivalent lanthanide ions

Abstract

A novel family of ferrocene-derivatised calix[4]arene ligands possessing ester amide and acid amide co-ordination groups has been prepared. UV/VIS, electrospray mass spectrometry and electrochemical co-ordination studies reveal these ligands form thermodynamically 1∶1 stable complexes with lanthanide ions. Electrochemical studies show these redox-active ligands electrochemically recognise trivalent lanthanide ions via significant anodic perturbations of the ferrocene–ferrocenium redox couple. With a ferrocene-bridged calixarene dimer containing ester, amide and phenolic co-ordination functionalities, anodic shifts as large as 200 mV are observed on addition of one equivalent of lanthanide ion.