Photoluminescent Mixed-Ligand Europium(III) Complex with 3,4-Dichloroisothiazole-5-Carboxylic Acid and 1,10-Phenanthroline

The structural characterization of 3,4-dichloroisothiazole-5-carboxylic acid is performed for the first time along with the preparation of the first coordination compound based on it - a mixed-ligand europium(III) complex with 3,4-dichloroisothiazole-5-carboxylic acid and 1,10-phenanthroline. The coordination compound is characterized by the elemental analysis, single crystal and powder X-ray diffraction (XRD), and IR spectroscopy. According to the single crystal XRD data, the obtained complex is a binuclear compound with the formula [Eu₂L₆(phen)₂(H₂O)₂]·6H₂O. Its structure corresponds to the Chinese lantern type. The isothiazole derivative exhibits both monodentate and bidentate-bridging coordinations binding europium ions. The photoluminescent properties of a polycrystalline sample of the complex are studied: the luminescence quantum yield is 23%, the excited state lifetime is 0.8 ms.