Comparison of the performance of calix[4]arene phosphine oxide and ester derivatives in ion-selective optode membranes

Abstract

Ion-selective optode membranes incorporating p-tert-butylcalix[4]arene methoxyethylester and p-tert-butylcalix[4]arene ethyleneoxydiphenylphosphine oxide (2, Fig. 1) as ion-selective ligands have been prepared. Striking differences in response to Group I and Group II metal ions are observed, with the ester derivative favouring sodium and the phosphine oxide derivative favouring calcium. An explanation for the basis of the different behaviour is suggested on the basis of molecular modelling.