Synthesis, Structures, and Photoluminescent Properties of Three Coordination Polymers based on an Asymmetric Semi-rigid V-shaped Tricarboxylate Ligand

Three coordination polymers, [Zn(HL)(phen)(H2O)](n) (1), [Zn-1.5(L)(4,4'-bpy)(1.5)](n)center dot 4nH(2)O (2), and [Zn-2(HL)(2)(bib)(2)](n)center dot 2nH(2)O (3), were assembled from the asymmetric semi-rigid V-shaped tricarboxylate ligand 4-(2-carboxy-phenoxy)-isophthalic acid (H3L) with 1,10-phenanthroline (phen), 4,4'-bipyridine(4,4'-bpy) and 1,4-bis(imidazol-1-yl) benzene (bib) as auxiliary ligands. Complex 1 features a one-dimensional (1D) double-looped chain, which is further extended into a 2D supramolecular layer via two kinds of hydrogen-bonding interactions. Complex 2 exhibits a complicated 3D framework, which can be rationalized as a (3,4,4)-connected trinodal net with a unique (4.8.10) (4.8.10.12(3)) (8(2).12(2).14.16) topology. Complex 3 has a two-dimensional (2D) (4,4) layer formed by the {Zn-2} dinuclear SUBs and the bib ligands. The structural and topological differences of the three complexes indicate that the N-containing auxiliary ligands play important roles in the formation of the final framework structures. In addition, complexes 1-3 were characterized by elemental analysis, IR spectroscopy, and X-ray powder diffraction. The thermal behaviors and luminescent properties of complexes 1-3 were also investigated in detail.