Four metal(II) ions induced complexes based on semi-rigid imidazolium carboxylate ligand: Syntheses, structures and properties

By modulating the synthetic strategy based on changing metal salt used in the synthesis, four new metal(II) complexes, [Cu(MIBA)2(H2O)3]·2H2O (C22H28CuN4O9) (1), [Ni2(MIBA)4(H2O)6]n (C44H48Ni2N8O14) (2), [Co(MIBA)2]n (C22H18CoN4O4) (3) and [Zn(MIBA)2]n (C22H18ZnN4O4) (4) constructed by 4-(1H-2-methylimidazol-1-yl)benzoic acid (HMIBA) were synthesized under hydrothermal/solvothermal conditions and characterized by single crystal X-ray diffraction, powder XRD, FT-IR, TGA and elemental analysis techniques. Although the four complexes were constructed by the same semi-rigid imidazolium carboxylate ligand, their structures are quite different. The structural analyses revealed that complex 1 is a discrete mononuclear unit, which are extended to form 3D supramolecular architectures by hydrogen bonds. Complex 2 features a 1D antenna-like chain, complex 3 exhibit a 2D + 2D → 3D structure, and complex 4 exhibits a 3D → 3D fourfold interpenetrating framework. Furthermore, the fluorescent properties and molecular simulation of the complex 4 was also investigated in the solid state at room temperature.