Syntheses, Structures and Characterization of Four Metal-Organic Frameworks constructed by 2,2′,6,6′-Tetramethoxy-4,4′-biphenyldicarboxylic Acid

Four metal-organic frameworks (MOFs), {[Mn3.5L(OH)(HCOO)4(DMF)]·H2O} (1), {[In2.5L2O(OH)1.5(H2O)2]·DMF·CH3CN·2H2O} (2), {[Pb4L3O(DMA)]·CH3CN} (3), and {[LaL(NO3)(DMF)2]·2H2O} (4) were synthesized by utilizing the ligand 2,2′,6,6′-tetramethoxy-4,4′-biphenyldicarboxylic acid (H2L) via solvothermal methods. All MOFs were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, and infrared spectroscopy. In 1, the Mn2+ ions are interconnected by formic groups in situ produced via DMF decomposition to form a rare 2D macrocyclic plane, which is further linked by L2– to construct the final 3D network. In 2, 1D zip-like infinite chain is formed and then interconnected to build the 3D framework. In 3, a [Pb6(μ4-O)2(O2C)10(DMA)2] cluster with a centrosymmetric [Pb6(μ4-O)2]8+ octahedral core is formed in the 3D structure. In 4, the La3+ ions are connected with each other through carboxylate groups of L2– to generate 1D zigzag chain, which is further linked by L2– to construct a 3D network with sra topology. Solid photoluminescence properties of 3 and 4 were also investigated.