Probing optical recognition of metal ions with employment of cationic dye-calix[4]arene supramolecular complexes

Abstract

Optical sensing of metal ions using calixarenes with covalently attached chromophores (fluorophores) has attracted considerable attention of researchers. However, the alternative approach involving host-guest complexes of calixarenes with dyes in metal recognition has been scarcely explored. In this work, addition of different metal cations to the aqueous solutions for solvent extraction of a cationic dye trans-4-[4-(dimethylamino)styryl]-1-methylpyridinium iodide by calix[4]arenes containing lower-rim proton-ionizable groups was found to produce significant effect on the absorption and fluorescence spectra of the organic phases. The observed spectral changes are attributed to co-extraction of the two substrates via formation of supramolecular complexes dye-calixarene-metal cation.