Synthesis, Structures And Characterization In A Series Of Coordination Polymers Based On Biphenyl-2,4’,5-tricarboxylic Acid And (E)- 5-(Pyridin-4-yl-methyleneamino)Isophthalic Acid

Recently, coordination polymers (CPs) have acquired extensive attention due to their novel topologies and intriguing architectures, and which can be potentially applied in various areas such as photoluminescence, magnetism, heterogeneous catalysis, gas and hydrocarbon separation and storage, ion exchange and so on. However, the construction of CPs is affected by a variety of factors, like organic ligands, metal ions, solvent, temperature and ratio of reactants etc. To be noted, appropriate organic ligand can extend the diversities of the CPs due to whose great difference in the lengths, flexibility and steric arrangement. In addition, the aromatic multicarboxylate ligands play an crucial role in tuning the framework among the alternative organic ligands, owing to the abundant coordination modes of which.In this paper, we choose bipheny 1-2,4’,5-tricar bo xylic acid and (E)-5-(Pyridin-4-yl-methyleneamino)isophthalic acid as primary ligands, and eight coordination polymers have been synthesized under solvothermal conditions, namely, [Zn(HL)(bibp)]n (1), [Co(HL)(bibp)]n (2), [Co(HL)(bib)]n (3), [Co1.5(L)(bib)1.5(H2O)]n (4), [Co(HL)(4,4’-bpy)(H2O)2]n (5), [Cu15(L)(2,2’-bpy)(H2O)]n (6), [Cu2.5(L)(2,2’-bpy)(MeO)(H2O)]n (7), [Cu2(A)(SO4)o.5(OH)]n (8). All of the above coordination polymers have been characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analysis. Structural analyses reveal that both 1 and 2 are isostructural coordination polymers and display a three dimensional and 4-fold interpenetrated frameworks. In complexes 3 and 4, the central metal ions connected with bib ligands to form an infinite chain. And then, the chain in 3 connected with H3L to form a 2D network. Due to the different coordination modes, the chain of 4 extend to a 3D network. The complex 5 shows a 2D layered structure and contains H-bonds.6 and 7 as a mixture with the same reaction, and present similar 2D structure. There are π-π conjugated effect within the structure. The complex 8 presents a 3D framework, and contains a "butterfly" structure SBUs. Moreover, photoluminescence property of 1 and the magnetic properties of 2-8 were studied. According to the structures of these eight complexes, we have discussed the effect of different auxiliary ligands and the different anions salt of same metal on the construction of CPs. The reaction processes of complexes 6-8 have also been experimented in detail.