Complexes of Eu(III), Tb(III) and Cu(II) with proton transfer compound between 2,6-pyridinedicarboxylic acid and 2-aminobenzothiazole: characterization of the structures and physical properties

Abstract

A proton transfer compound, (ABTH)+(PydcH)− (1), obtained from 2-aminobenzothiazole (ABT) and 2,6-pyridinedicarboxylic acid (Pydc) as well as its Eu(III), Tb(III), and Cu(II) complexes (ABT)3[Eu(Pydc)3]·5H2O (2), (ABT)3[Tb(Pydc)3]·5H2O (3), and (ABT)[Cu(Pydc)(PydcH)]·3H2O (4) were obtained under ambient conditions and structurally verified by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, powder X-ray diffraction (PXRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and magnetic measurements. Compounds 2–4 are the first known solids containing complex anions with Pydc ligands, 2-aminobenzothiazole cations (ABT), and solvate water molecules. During the synthesis of 3, a secondary phase with the formula ABTCl∙H2O was obtained and characterized by elemental analysis and single-crystal X-ray diffraction. The asymmetric unit of 5 consists of six symmetry independent ABT cations, six chlorides, and six water molecules. The two lanthanide complexes showed characteristic emissions of Eu3+ and Tb3+ ions. The good solubilities of these complexes in water and their luminescence properties make them attractive luminescent labels of biological molecules.