Tunable chemical sensors: Light-switched ion selective electrodes on the basis of a photoresponsive calix [4] arene

Immobilization of a novel photoresponsive ionophoric calix [4]arene (1) in plasticized poly (vinyl chloride) membranes provided new Switch-functionalized Ion Selective Electrodes (SISEs). In comparison with the conventional ion selective electrodes technique, one significant advantage was obtained that the SISEs method can reversibly regulate the selectivity from one target ion to other ions by external light irradiation. Ion selectivity studies demonstrated that the electrodes using ligand 1 plasticized with tris(2-ethylhexyl) phosphate or di(2-ethylhexyl) phthalate showed affinity for Li⁺ ion or Cs⁺ ion, respectively, against other alkali and alkaline earth metal ions in the dark whereas the excellent Na⁺ ion selectivity appeared upon 365 nm irradiation. This is a new methodology to assign one electrode to detect two metal ions.