Selective fluoride recognition and potentiometric properties of ion-selective electrodes based on bis(halodiphenylstannyl)alkanes

Abstract

A series of bis(halodiphenylstannyl)alkanes (Ph 2XSn) 2(CH 2) n , (X: Cl, Br, OAc, n=1–4) have been evaluated as fluoride ionophores in polymeric-membrane ion-selective electrodes. It is shown that the selectivity pattern of these molecules is governed by their structural characteristics. An entirely non-Hofmeister selectivity sequence with a remarkable preference towards fluoride is obtained for bis(chlorodiphenylstannyl)methane, (Ph 2ClSn) 2CH 2. The latter compound was utilised for further studies on the improvement of the ISEs selectivity towards fluoride. The optimum membrane composition for best potentiometric performance was achieved with DOS-elasticised membranes doped with 10 mol% KTpClPB, suggesting that this compound operates via a charged-carrier mechanism. This membrane composition results in a preference to fluoride over several lipophilic anions, such as perchlorate, nitrate and iodide.