A series of new lanthanide complexes with 2-bromo-5-methoxybenzoic acid and 5,5′-dimethyl-2,2′-bipyridine: Crystal structures, thermal behavior, luminescent and magnetic properties: Structures, thermal behavior, luminescent and magnetic properties

Four new binuclear lanthanide complexes [Ln(2-Br-5-MOBA)(3)(5,5-DM-2,2-bipy)](2) (Ln=Gd(1), Tb(2), Dy(3), Er(4); 2-Br-5-MOBA=2-bromo-5-methoxybenzoate; 5,5-DM-2,2-bipy=5,5-dimethyl-2,2-bipyridine) have been successfully synthesized and then further characterized by infrared spectra, single-crystal X-ray diffraction, elemental analyses and Powder X-ray diffraction (PXRD). Complexes 1-3 are isostructure with the coordination number of nine, while the complex 4 is eight-coordinated exhibiting a different structure. Nevertheless, the complexes 1-4 form the same 1D, 2D and 3D supramolecular structures by hydrogen bonding (C-HBr and C-HO) and - stacking interactions. Thermal behavior of complexes 1-4 was studied by TG/DSC-FTIR techniques. The luminescent spectra of complexes 2 and 3 were investigated at room temperature, which exhibits characteristic luminescence of Tb3+ and Dy3+ ions, respectively. The luminescence decay curve of the complex 2 was measured, which follows double-exponential decay law. The luminescence lifetime of complex 2 is 0.693ms. What's more, the magnetic properties of complexes 1-4 have been investigated by measuring the magnetic susceptibility in the temperature range of 2-300K.