Synthesis, crystal structure and properties of Mn/Ni/Co 3D network structures based on 2, 5-bis(trifluoromethyl) terephthalic acid ligands

2,5-bis(trifluoromethyl)terephthalic acid (H 2 L 1 ) as the main ligand and 1,10′-phenanthroline (L 2 ) as the co-ligand were reacted with manganese chloride tetrahydrate (MnCl 2 ·4H 2 O), nickel sulfate hexahydrate (NiSO 4 ·6H 2 O) and cobalt nitrate hexahydrate (Co(NO 3 ) 2 ·6H 2 O) by solvothermal reaction to give the manganese complex [Mn 2 (L 1 ) 2 (L 2 ) 2 ] n ( 1 ), the nickel complex {[Ni 3 (L 1 ) 3 (L 2 ) 2 (H 2 O) 4 ]·2DMF} n ( 2 ) and the cobalt complex {[Co 2 (L 1 ) 2 (DMF) 2 ]·H 2 O} n ( 3 ). The structures were characterized and their properties studied by means of single-crystal X-ray diffraction, infrared spectroscopy, elemental analysis, ultraviolet spectroscopy, fluorescence spectroscopy, thermogravimetric analysis. The single-crystal structure analysis showed that the complexes 1 – 3 are infinitely extended three-dimensional network-like structures of space groups P 1 - , P 1 - , P 2 1 / n , respectively. The results of fluorescence analysis and thermogravimetric analysis showed that complexes 1 – 3 have good thermal stability and fluorescence properties, respectively. Complex 3 can also maintain good thermal stability at 230 °C, and the maximum fluorescence emission wavelength is 370 nm.