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Abstract
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Three Zn( II ) complexes, namely mononuclear derivatives [Zn(H 2 L) 2 I 2 ]2CH 3 OH (1) and [Zn(H 2 L) 2 Br 2 ] 2CH 3 OH (2) and a tetranuclear cyclic compound [Zn 4 (H 2 L) 4 Cl 8 ]4CH 3 OH (3) {H 2 L = p-hydroxy- benzaldehyde isonicotinoylhydrazone}, were synthesized using a self-assembly method and fully characterized. Characterization included theoretical methods and single crystal X-ray diffraction. The molecular structures of compounds 1–3 demonstrate the effect of halide ions and the binding mode of H 2 L on self-assembly. The arrangement of the packing patterns in 1–3 is well explained by various types of non-covalent interactions. Notably, several types of strong H-bonding, C–H O, and p p interactions were also observed, which assist in the formation of 3D supramolecular networks. In the isostructural compounds 1 and 2, a tripod type H-bonding interaction of H 2 L with the methanol molecules of crystal- lization was observed. Furthermore, the terminal halide ligands exert H-bonding interactions with the –OH/–NH and –CH moieties of H 2 L. In all compounds, the supramolecular 3D networks, driven by strong H-bonding interactions, were simplified by topologial analysis. This showed a 6-connected framework with a unique topology in 1 and 2, and an 8-connected framework with bcu topology in 3 (the latter is composed of cyclic tetrazinc( II ) cluster units with 2M4-1 topology). In addition, the discussion on coordi- nation geometries and non-covalent interactions was also supported using Hirshfeld surface analysis and DFT calculations.
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