Different two-dimensional metal-organic frameworks through ligand modification

Through ligand modification, we have replaced the central benzene ring of H2TDBA ([1,1': 3', 1.-terphenyl]-4,4.-dicarboxylicacid) with the pyridine structurally related ligand H2PDDA (4,4'-(pyridine-2,6-diyl) dibenzoic acid), which makes the central pyridine ring of H2PDDA more coplanar with two benzene rings on both sides of the ligand. The modification results in a dramatically different linkage configuration, thereby allowing structural changes to the metal-organic frameworks (MOFs). Two 2-D MOFs, [Cu(TDBA)(DMA)2].H2O (BUT-221, DMA = N,N-dimethylacetamide), and [Cu 3 (PDDA) 3 (DMA) 2 (H2O)].5H2O (BUT-223) have been synthesized through reactions of two ditopic carboxylate ligands with Cu(NO3)2.3H2O under solvothermal conditions, and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. Topological analysis shows that BUT-221 is a twofold parallel interpenetrating 44 2-D network with a skl topology, while BUT-223 is a 2-D network with a kgm topology.