Syntheses, structures and magnetic properties of nine coordination polymers based on terphenyl-tetracarboxylic acid ligands.

Abstract

Nine coordination polymers (CPs) [Mn(H3L)(H2L)0.5(phen)]n (1), [Ni2L(phen)2(μ2-H2O)]n (2), {[Mn2L(phen)2]·(DMA)(H2O)}n (3), {[Co2L(μ2-H2O)(μ2-DMA)]·DMF}n (4), [CoL0.5(H2O)(phen)]n (5), {[Ni2L(μ2-H2O)(μ2-DMA)]·DMA}n (6), {[Co2L(μ2-H2O)(μ2-DMA)]·DMA}n (7), {[Ni2L(μ2-H2O)(H2O)2(DMF)2]·(H2O)2(DMF)}n (8), and {[Ni4L2(μ2-H2O)4(H2O)2]·(H2O)2(NMP)}n (9) (H4L = 1,1':4',1''-terphenyl-2',4,4'',5'-tetracarboxylic acid, DMA = N,N-dimethylacetamine, DMF = N,N-dimethylformamide, NMP = N-methyl-2-pyrrolidone, phen = 1,10-phenanthroline) have been synthesized and structurally characterized. Crystal structural analyses reveal that 1 features the uninodal 2D (4,4) network with the dinuclear Mn2(COO)2 units as 4-connected nodes. 3 and 5 possess the binodal 2D (4,4) network with dinuclear Mn2(COO)4/Co2O2 units and L4- ligands as 4-connected nodes, respectively. In 2 and 8, each dinuclear Ni2(COO)2(μ2-H2O) unit links to four L4- ligands and each L4- ligand bridges four dinuclear Ni2(COO)2(μ2-H2O) units to generate the 3D framework, which can also be rationalized as a binodal 4,4-connected (42·84)(42·84) topological network by considering the dinuclear Ni2(COO)2(μ2-H2O) units as non-planar 4-connected nodes and L4- ligands as planar 4-connected nodes, respectively. In 4, 6-7 and 9, there exist a series of parallel-aligned metal-carboxylate chains, which are linked along two directions by para-terphenyl moieties of L4- ligands to generate the 3D frameworks. Moreover, direct current magnetic susceptibility measurements were carried out to study their magnetic properties. In complexes 2 and 9, weak ferromagnetic interactions between the magnetic centers were observed. In addition, the other compounds show weak antiferromagnetic exchange interactions between the adjacent metal ions.