Five diverse bivalent metal coordination polymers based on benzene dicarboxylate and bent dipyridyl ligands: syntheses, structures, and photoluminescent properties

Abstract

Five new mixed ligand coordination polymers, {[Co_0.5(H₂O)(1,4-bdc)(3-bpdb)Co_0.5(H₂O)₂]·(H₂O)₃}_n (1), [Co(3-bpdh)(1,4-bdc)(H₂O)₂]_n (2), [Zn(3-bpdb)(1,4-bdc)]_n (3), {[Zn(3-bpdh)(1,4-bdc)]·(3-bpdh)_0.5}_n (4) and [Cd(3-bpdb)(1,4-bdc)(H₂O)]_n (5) [where 3-bpdb = 1,4-bis-(3-pyridyl)-2,3-diaza-1,3-butadiene; 3-bpdh = 2,5-bis-(3-pyridyl)-3,4-diaza-2,4-hexadiene and 1,4-bdc = benzene-1,4-dicarboxylate] were synthesized at room temperature. The structures of 1–5 were determined by single crystal X-ray diffraction analysis and were further characterized by elemental analysis, infrared spectroscopy (IR) and powder X-ray diffraction (PXRD). Compound 1 exhibits a one-dimensional (1D) chain structure with monodentate pendant 1,4-bdc ligands which further extend to a three-dimensional (3D) supramolecular structure by H-bonding and π⋯π interactions. Compound 2 displays a 4-connected two-dimensional (2D) framework with the point symbol {4⁴·6²}. Moreover, the 2D structure of 2 is also ultimately packed into 3D supramolecular frameworks through H-bonding and π–π stacking interactions. Compound 3 shows a 5-fold interpenetrated diamondoid net with 6⁶ topology. Compound 4 is a 2D 3-connected net having a point symbol {6³} and is extended to a supramolecular 3D structure through C–H⋯π and π⋯π interactions with lattice 3-bpdh ligands. Compound 5 features a 3-fold interpenetrated diamondoid net with 6⁶ topology. The thermal stabilities and luminescent properties of 3–5 were also studied in detail. The complexes exhibit ligands based photoluminescence properties at room temperature.