Zinc(II) and cadmium(II) coordination polymers with a tricarboxylate containing reduced Schiff base ligand: Structural characterization and luminescent property

Three new coordination polymers, [Cd(HL)(phen)]·2H2O (1), [Zn2(L)(HCOO)(bpy)2]·H2O (2) and [Zn2(L)(μ3-OH)(bpy)]·1.5H2O (3) [H3L = 5-(4-carboxybenzylamino)isophthalic acid, phen = 1,10-phenanthroline and bpy = 2,2′-bipyridine], have been prepared and characterized by single crystal and powder X-ray diffraction, IR, elemental and thermogravimetric analyses. Complex 1 displays a 1D neutral double-stranded chain structure. Complex 2 shows the uninodal 3-connected 2D (4.82) fes network with in-situ generated [Zn2(COO)2(bpy)2] as the secondary building unit (SBU). Complex 3 exhibits the 2-nodal (3,6)-connected 2D (43)2(46.66.83) kgd net architecture containing in-situ generated [Zn4(COO)4(μ3-OH)2(bpy)2] (SBU). Significantly, concrete hexanuclear clusters (Zn4O2) exist in 3. Taking hydrogen bonding interactions into account, extended 3D supramolecular frameworks of 1–3 can be built. The influences of the coordination modes of the ligand, coordination geometries of the metal centers, steric hindrance as well as reaction temperature on the structures of the resultant complexes are discussed. Furthermore, the luminescent properties of 1–3 were preliminarily investigated.

Graphical abstractZn(II) and Cd(II) nitrate salts react with 5-(4-carboxybenzylamino)isophthalic acid (H3L) in the presence of phen or bpy as auxiliary ligands under hydrothermal conditions to yield three new complexes, showing 1D and 2D structures. The results of this study illustrate the structural diversity of the complexes under different experimental conditions.Figure optionsDownload full-size imageDownload as PowerPoint slide