Synthesis, structures and physical properties of mixed-ligand coordination polymers based on a V-shaped dicarboxylic ligand

Four coordination polymers formulated as [Ni2(hfipbb)2(2,2′-bipy)2(H2O)4] (1), [Ni(4,4′-bipy)(hfipbb)(H2O)]·0.5DMF (2), [Ni2(hfipbb)2(BPE)1.5(H2O)(μ2-H2O)]·DMF·2H2O (3) and Zn(hfipbb)(2,2′-bipy)·0.5DMF (4) (H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid); 2,2′-bipy = 2,2′-bipyridine; 4,4′-bipy = 4,4-bipyridine; BPE = 1,2-di(4-pyridyl)ethane; DMF = N,N-dimethylformamide) have been synthesized under solvothermal conditions based on the V-shaped H2hfipbb ligand and different auxiliary linear N-containing ligands. Compound 1 exhibits a three dimensional (3D) supramolecular network built from 0D rings linked through hydrogen bonds and π–π packing interactions. Compound 2 displays a 3D 3-fold interpenetrating diamond network with a point symbol of (66). Compound 3 gives a double layer structure with (44·62)-sql topology built from {Ni2} clusters bridged by BPE and hfipbb2− ligands. Compound 4 is a 3D array formed by interdigitated 1D zigzag [Zn2(hfipbb)2]n ribbons, in which the Zn2(COO)4 paddle-wheel SBUs are linked by two hfipbb2− ligands. Compounds 2–4 exhibit hydrophobic properties which may have potential applications in hydrophobic materials. The temperature-dependent magnetic susceptibility study shows that compound 3 exhibits antiferromagnetism properties. The photoluminescence of 4 was studied in the solid state at room temperature, and it shows broad emission with a maximum peak at around 385 nm upon excitation at 335 nm.