Lanthanide complexes with 2-bromo-5-methoxybenzoic acid and 5,5′-dimethyl-2,2′-bipyridine: Crystal structures, thermodynamic properties and luminescence behaviors

Abstract

Abstract Two ternary lanthanide complexes [Ln(2-Br-5-MOBA)3(5,5′-DM-2,2′-DIPY)]2 (Ln = Sm(1), Eu(2); 2-Br-5-MOBA = 2-bromo-5-methoxybenzoate; 5,5′-DM-2,2′-DIPY = 5,5′-dimethyl-2,2′-bipyridine) with 2-bromo-5-methoxybenzoic acid and 5,5′-dimethyl-2,2′-bipyridine have been synthesized and characterized. The Single-crystal X-ray diffraction date show that complexes 1 and 2 are isostructural in the triclinic system, space group P 1 ¯ . Infrared spectra (IR) and X-ray powder diffraction (PXRD) further confirm that complexes 1 and 2 are isostructural. The basic structural unit forms a 1D chain through the weak C H⋯Br hydrogen bond interaction along the b-axis, and forms a 2D sheet through the π–π stacking interactions along the a-axis. The 2D sheets are further interconnected by the C H⋯O hydrogen bond interaction to assembled into a 3D supramolecular network along the c-axis. In addition, the simultaneous thermal analysis (TG, DTG and DSC) of the complexes and the FTIR spectra of the escaped gas were measured. The heat capacities of the complexes were determined by DSC in the temperature region of 258.15–393.15 K. Furthermore, the luminescence spectrum of the complexes 1 and 2 and luminescence lifetime of complex 2 were also measured.