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A series of mixed-ligand coordination complexes have been prepared using diffusion method, by reacting the CoII, NiII, ZnII, AgI, CdII, CuII, or PbIInitrate with tetrabromoterephthalic acid (H2tbta) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo). These complexes show various 0D, 1D, 2D, and 3D coordination motifs with different geometries of the metal centers, indicating a metal-directed assembly. The synthetic condition will also affect the resulting crystalline products for ZnIIspecies. Crystal structure analysis reveals that secondary interactions such as hydrogen bonding and aromatic stacking will further extend the coordination arrays to diverse supramolecular architectures. All complexes have been characterized by IR, elemental analysis, and powder X-ray diffraction techniques. In addition, the polymeric coordination systems with d10metal centers show solid-state fluorescent emissions at room temperature, which thus may be applied as potential hybrid luminescent materials. [ABSTRACT FROM AUTHOR]

This work presents eight coordination assemblies based on divalent metal ions (M = CoII, CuII, ZnII, and CdII), dicyanamide anion (N(CN)2−, dca), and two isomeric bent dipyridyl coligands (L), namely, 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo). In the resulting crystalline materials, both bpo and dca tectons generally display the bidentate bridging fashion (except in the mononuclear species 5), extending the metal centers to afford diverse one-, two-, and three-dimensional (1-D, 2-D, and 3-D) coordination networks that are not commonly observed in M−dca−L systems. Notably, the inclined polycatenated 2-D → 3-D framework and 3-D polyknotting network with the unique 6-connected (44.611) topology are formed for the CuIIand CdIIspecies with dca and 4-bpo. For the polymeric CoIIand CuIIcomplexes, very weak antiferromagnetic or ferromagnetic interactions are observed between the metal centers due to the μ1,5-bridging mode of dca, and their magneto-structural correlations have been discussed in detail. The ZnIIand CdIIcomplexes show solid-state fluorescent emissions at room temperature. [ABSTRACT FROM AUTHOR]

A series of CdII, CoII, NiII, and PbIImixed-ligand coordination complexes 1−8based on 5-sulfoisophthalic acid (H3sip) and the bent dipyridyl ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) or its 4-pyridyl N-donor analogue (4-bpo) have been synthesized and fully characterized by IR spectra, microanalyses, and single crystal and powder X-ray diffraction techniques. The significant pH effect on assembly of the CdIIcomplexes 1−4has been demonstrated, which leads to the formation of distinct crystalline products, whereas the CoII, NiII, and PbIIsystems 5−8are independent to pH condition of the synthetic reaction. Complexes 1−8display various coordination motifs with different existing forms, conformations, and coordination modes of the organic ligands. Further, extended supramolecular networks are constructed via secondary interactions such as hydrogen-bonding and aromatic stacking. Solid-state properties of thermal stability and fluorescence for these crystalline materials are also presented. [ABSTRACT FROM AUTHOR]