Syntheses, structures and properties of five Cu(II) coordination polymers derived from semi-rigid bis-pyridyl-bis-amide and nitro-substituted aromatic carboxylates

Five new coordination polymers (CPs) based on two semi-rigid bis-pyridyl-bis-amide ligands and different nitro-substituted carboxylates, namely [Cu(3,5-dnb)(μ2-OH)] (1), [Cu4(4-bpcc)2(3,5-dnb)6(μ3-OH)2(H2O)2] (2), [Cu(4-bpcc)2(5-Hnip)2] (3), [Cu3(4-bpcc)(5-nip)2(5-Hnip)(μ3-OH)(H2O)]·4H2O (4), and [Cu(3-bpcc)(5-nip)]·2H2O (5) (3,5-Hdnb = 3,5-dinitrobenzoic acid, 5-H2nip = 5-nitroisophthalic acid, 4-bpcc = N,N′-bis(4-pyridinecarboxamide)-1,2-cyclohexane, and 3-bpcc = N,N′-bis(3-pyridinecarboxamide)-1,2-cyclohexane), were synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, TG analysis and powder X-ray diffraction. Complex 1 shows a 3D framework, which features a (3,5)-connected topology with the Schläfli symbol of {3 · 72}{32 · 75 · 83}. Complex 2 displays a 3D supramolecular structure based on the tetranuclear [Cu4(3,5-dnb)6(μ3-OH)2] clusters, while complex 3 presents a 3D supramolecular architecture with mononuclear Cu(II) subunits. Complex 4 was obtained at a higher pH value than that in 3, which exhibits a uninodal 5-connected 3D bnn framework constructed from 1D ladder-like chains and μ2-bridging 4-bpcc ligands. Complex 5 is a 2D (4,4)-network based on a 1D [Cu(3-bpcc)]n meso-helixe and a 1D [Cu(5-nip)]n zigzag chains. The bis-pyridyl-bis-amide ligands and nitro-substituted carboxylates, as well as pH show great influence on the formation and various structures of the title complexes. The fluorescent and electrochemical properties of the title complexes were investigated.

Five new coordination polymers (CPs) have been constructed from two semi-rigid bis-pyridyl-bis-amide and nitro-substituted carboxylic acids mixed-ligands. The organic ligands and pH play important roles in determining the structural diversity. The fluorescent and electrochemical properties of the title complexes were investigated.Figure optionsDownload as PowerPoint slide