Spectral Study of Dynamic Complexes of Azomethinocoumarin-Coumarinospiropyran Hybrid Compound with Tb 3+ Ions

Spectral-kinetic and fluorescence properties of hybrid compound, whose molecule includes the photochromic spiropyran fragment and two fluorophores—coumarin and salicylideneimine, were studied in comparison with model compounds—7-hydroxy-4-methylcoumarin, spiropyran of coumarin type and azomethinocoumarin in mixed toluene–acetonitrile solution in the presence of Tb 3+ ions. It was shown that the hybrid compound exhibited direct photochromic transformations. Different fluorescence of complexes of the initial spirocycle and UV irradiation-induced merocyanine forms were observed. One green fluorescence emission with a maximum at 570 nm was observed for the initial closed form in mixed solvent solution and the additional red emission of the open merocyanine form in the region of 640 nm appeared after UV irradiation. The merocyanine form fluorescence in the presence of Tb 3+ ions extremely increased after irradiation with visible light.