Hydrothermal Synthesis And Electrochemical Properties Of Copper-lanthanide Coordination Polymers Based On Pyridine-2,3-dicarboxylic Acid

In this paper,by using copper and lanthanide ions as central metals,pyridine-2,3-dicarboxylic acid（2,3-H₂pydc）as main ligand,and N,N′-di（4H-1,2,4-triazole）hexanamide（dth）and N,N′-di（4H-1,2,4-triazole）-1,4-cyclohexanedicarboxamide（dtcd）as auxiliary ligands,fifteen coordination polymers（CPs）were synthesized under hydrothermal conditions,namely,[LnCu（2,3-pydc）2（adi）0.5（H₂O）3]·2H₂O [Ln = La（1）,Pr（2）,Nd（3）,H₂ adi =adipic acid],[Ln2Cu3（2,3-pydc）6（H₂O）10]·8H₂O [Ln = Sm（4）,Eu（5）,Gd（6）,Tb（7）,Dy（8）,Er（9）,Yb（10）,Lu（11）],[Ln2Cu3（2,3-pydc）6（H₂O）6]·xH₂O [Ln = La（12,x = 8）,Nd（14,x = 10）] and [Ln2Cu2（2,3-pydc）4（NO3）（OH）（H₂O）6]·2H₂O[Ln = La（13）,Nd（15）].They were characterized by X-ray single-crystal diffraction,elemental analysis,IR,X-ray powder diffraction,and thermogravimetric analysis,and their electrochemical properties were studied.CPs 1–11 show two types of three-dimensional（3D）architectures with different topologies.The adi anion is derived from the in situ hydrolysis of dth.In 1–3,the binuclear Cu2（2,3-pydc）4 and Ln2（COO）2 units are connected to each other to form a two-dimensional（2D）layer,and the adi anion is connected to the adjacent 2D layer to form a 3D framework.In 4–11,the trinuclear Cu3（2,3-pydc）6 units are regularly arranged to form a 2D supramolecular layer,and the rare earth ions connect the 2D supramolecular layers to form a 3D framework.CPs 12-15 show two types of 3D structures with different topologies.In 12 and 14,the Cu（2,3-pydc）2 and Ln2（COO）4 units are connected to each other to form a 2D layer,and the adjacent 2D layers are linked by Cu（2,3-pydc）4 into a3 D framework with one-dimensional（1D）channels.In 13 and 15,the LnIII ions bridge the 1D chains based on 2,3-pydc and CuII into a 2D layer,and the nitrate and hydroxyl anions connect the adjacent 2D layers to produce a 3D frameworkwith 1D channels.