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Structures, Single-Molecule Magnets, and Fluorescent Properties of Four Dinuclear Lanthanide Complexes Based on 4-Azotriazolyl-3-hydroxy-2-naphthoic Acid

Research paper by Shang-Fang Xie, Li-Qian Huang, Li Zhong, Bi-Lin Lai, Meng Yang, Wen-Bin Chen, Yi-Quan Zhang, Wen Dong

Indexed on: 14 Aug '19Published on: 22 Apr '19Published in: Inorganic Chemistry



Abstract

Four isostructural dinuclear lanthanide (Ln = Dy (1), Tb (2), Sm (3), Eu (4)) complexes based on 4-azotriazolyl-3-hydroxy-2-naphthoic acid (H3ATNA) have been synthesized and characterized by single-crystal X-ray diffraction analysis. The organic ligand has a particular antenna effect in which it only sensitizes Eu(III) fluorescence. Dy(III) complex is single-molecule magnet, and the magnetic behavior was rationalized through ab initio calculations.Four isostructural dinuclear lanthanide complexes based on 4-azotriazolyl-3-hydroxy-2-naphthoic acid (H3ATNA) and 3-hydroxy-2-naphthoic acid (H2NA) ligands, {[Ln2(HATNA)2(HNA)2(H2O)4]·6DMF} (Ln = Dy (1), Tb (2), Sm (3), Eu (4); DMF = N,N-dimethylformamide) have been prepared and characterized by X-ray diffraction crystallography, dc/ac magnetic characterization, and fluorescent spectrometry. The crystallographic data reveal dinuclear lanthanide cores of complexes 1–4, bridged by phenoxo and μ1,3 carboxyl groups. Each nine-coordinated Ln(III) ion is located in a slightly distorted monocapped square antiprism. The ligand of H3ATNA displays a unique antenna effect in complex 4. Complexes 1–3 display only two ligand-centered fluorescent emissive peaks around 450 and 600 nm, and complex 4 shows four characteristic Eu(III)-centered emission bands at 593, 618, 653, and 698 nm under excitation at 348 nm. Complex 1 exhibits single-molecule magnet behavior that is rationalized through ab initio calculations.

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