Arylidene-Imidazolones and Their Acyclic Analogue as Fluorescent Sensors of Metal Ions

Objective: Synthesis of a series of methylene-imidazolones with complexing groups. Methods: The formation of imines with the following [2+3]-cycloaddition and recycling. The use of phosphazene to form an acyclic analogue. The optical properties were studied with and without ions of metals. The spectrofluorimetric titration was carried out to evaluate the binding constants. Results and Discussion: We discovered that for hydroxyquinolinidene-imidazolone and difluorobenzimidazolidene-imidazolone, which practically did not exhibit fluorescence in the free form, a noticeable increase in fluorescence was observed when binding to the Cd²⁺ and Zn²⁺ cations. Conclusions: Two compounds from a new synthesized series were found to be promising fluorescent sensors of cadmium and zinc ions and potential labels for monitoring intracellular processes.