Interactions of stilbazolium merocyanine with transition metal ions

The visible absorption spectra of merocyanine 1-(12-hydroxydodecyl)-4-[(3-hydroxy4-oxocyclohexa-2,5-dienylidene)-ethylidene]-1,4-dihydropyridine in the presence of Cu2+, Co2+ and Fe3+ ions has been investigated. The metal ions impacted a long wave absorption band of merocyanine with a characteristic wavelength. Both the intensity of the maximum and its position are related to changes in the metal ion concentration. This observed behaviour was dependent on the pH of the solution. Since concentrations of metal ions below 10-6 M l-1 can be detected, we concluded that the investigated dye demonstrated a high sensitivity for the presence of metal ions.