Syntheses, structures and properties of a series of heterometallic-organic frameworks based on pyridinedicarboxylic acids

Six novel heterometallic-organic frameworks (HMOFs), namely [LaCu(2,5-pydc)2(H2O)4]Cl (1), [LaNi(2.5-pydc)2(H2O)4]Cl·4H2O (2), [LaCu2Cl3(4,4′-bpdc)2(H2O)3]·H2O (3), [CeCuCl2(5,5′-bpdc)(HCO3)(H2O)] (4), and [MSr2Cl(3,5-pydc)2(NO3)(H2O)]·3.5H2O [M ​= ​Ni (5), Co (6)] (2,5-pydc ​= ​pyridine-2,5-dicarboxylic acid, 4,4′-bpdc ​= ​2,2′-bipyridyl-4,4′-dicarboxylic acid, 5,5′-bpdc ​= ​2,2′-bipyridyl-5,5′-dicarboxylic acid, 3,5-pydc ​= ​pyridine-3,5-dicarboxylic acid), have been solvothermally synthesized on the basis of the coordination between alkaline earth/rare earth/transition metal ions and pyridinedicarboxylic acids. These HMOFs were characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, and thermogravimetric analysis. All these HMOFs have three-dimensional frameworks except compound 3 featuring a two-dimensional neutral layer. Magnetic property of 4 and luminescent spectra of 1–4 were studied.