cg100465u_si_002.cif (140.81 kB)

Coordination Assemblies of CoII/CuII/ZnII/CdII with 2,5-Bipyridyl-1,3,4-Oxadiazole and Dicyanamide Anion: Structural Diversification and Properties

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posted on 07.07.2010, 00:00 by Miao Du, Qian Wang, Cheng-Peng Li, Xiao-Jun Zhao, Joan Ribas
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 CuII and CdII species with dca and 4-bpo. For the polymeric CoII and CuII complexes, 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 ZnII and CdII complexes show solid-state fluorescent emissions at room temperature.