Double-armed crown ethers: Synergic π-coordination effect on potentiometric sensing for Ag(i)

Abstract

Three diaza-18-crown-6 derivatives having methyl (L₁), methoxy (L₂) and phenyl (L₃) end-groups in para-substituted phenolic side-arms have been investigated as potentiometric sensing materials for silver(I)-selective poly(vinyl chloride) membrane electrodes. The aim of the present work is to establish whether a combination of macrocyclic coordination to Ag⁺ ion and Ag-π interaction might produce synergic effect in Ag⁺ ion sensing. The electrode based on the aromatic end-groups, L₃ was found to give remarkably better electrochemical performance than their aliphatic counterparts (L₁ and L₂). The sensing ability for Ag⁺ ion with the proposed electrode was enhanced noticeably due to the π-coordination of Ag⁺ ion, which was elucidated by NMR. The present findings may serve as an alternative approach for designing advanced sensing materials.