Synthesis and Functions of 1, 10-Phenanthroline Derivatives as Ionophores

Abstract

A number of 1, 10-phenanthroline derivatives such as 2, 9-dialkyl phenanthroline derivatives, biscrown derivatives with crown ether moieties connected via amide linkages at the 2- and 9-positions, and oligomethylene bridged phenanthrolines which work as ionophores were synthesized. Their properties not only as sensing agents for ion-selective electrodes (ISEs) and fluorometry, but also as agents for selective ion transport were investigated. It was found that 2, 9-dibutyl-1, 10-phenanthroline is an excellent Li⁺-sensing agent for both ISEs and fluorometry. 1, 6-Bis (9-butyl-1, 10-phenanthrolin-2-yl) -hexane, which is one of the bridged bisphenanhtrolines, exhibits high selectivity toward Li⁺ among alkali and alkaline earth metal ions in liquid membrane system. Phenanthroline derivative with bis (benzo-15-crown-5) moieties works as a highly selective K⁺ carrier. The relationship between their structure and function is also discussed.