Barium ion sensing by a 2,2′-binaphthalene derivative bearing two monoaza-15-crown-5 ethers

A novel fluoroionophore 1 based on 2,2′-binaphthalene bearing two monoaza-15-crown-5 ethers at 8- and 8′-positions was prepared. UV–vis and fluorescence responses of 1 upon the addition of alkali and alkaline earth metal cations were evaluated in 15% MeOH–MeCN. Receptor 1 showed unique response for Ba2+ due to the formation of an intramolecular sandwich complex.