Abstract
Two coordination complexes based on H4btec and H2bibzim (H4btec = 1,2,3,5-benzenetetracarboxylic acid, H2bibzim = 2,2′-bibenzimidazole), [Ni(H2bibzim)3]2(btec) (1) and [Zn(H2bibzim)(btec)0.5]n (2), have been synthesized by hydrothermal methods and characterized by single-crystal X-ray diffraction. Complex 1 is composed of [Ni(H2bibzim)3]2+ with free btec4− as counter anion. In 2, the btec4− ligands bridge the Zn(II) ions into a 1-D chain with H2bibzim as auxiliary chelating ligands. Interesting supramolecular structures were demonstrated due to the existence of hydrogen bonding as well as π⋯π interactions in the two different complexes. The H2bibzim ligands act as a 2-connected spacer in both complexes. However, in 1, the [Ni(H2bibzim)3]2+ cations act as 3-connected nodes, hydrogen bonded with the 6-connected btec4− ligands into a 3-D framework with (3,6)-connected topology Schläfli symbol as (4.6.8)(42.6)(43.64.87.10). As for 2, Zn serves as a 3-connected node with btec4− as a 6-connected node, leading to a 2D (3,6)-connected hydrogen bonding kgd topology sheet with Schläfli symbol of (43)2(46.66.83). Thermal stabilities and photoluminescent properties of 1 and 2 were also studied.
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