Chromoionophores derived from a coumarin linked to monoaza-and diaza-crown ethers: Formation of divalent 3d metal complexes

The complexing properties of a series of Chromoionophores consisting of a C-153 coumarin linked to an aza- or diaza-crown ether are studied in acetonitrile and methanol by UV spectrometry. Cations under study are copper, nickel, zinc, cadmium and lead. The high stability constants of the complexes arise from the participation of the carbonyl group of the coumarin into the complexes and from the deconjugation of the nitrogen atom of the aza-crown ether from the π-electron system. A comparison made with previous results obtained for alkaline-earth cations shows that the new complexes present in most cases more shifted characteristic absorption wavelengths.