Selectivity in redox-switched calix[4]arene cationophores: electrochemical detection of a conformational change on cation binding

Abstract

Three 4-tert-butylcalix[4]arenes bearing a 1,8-bis(ethyleneoxy)anthraquinone bridge between alternate phenolic oxygen atoms, on one-electron reduction, show enhanced binding of alkali-metal cations with selectivities dependent upon the groups attached at the other phenolic oxygens; for one of the compounds, binding of potassium but not sodium is accompanied by a conformational change of the calixarene from cone to partial cone.