Syntheses And Properties Of Copper-Lanthanide Heterometallic Coordination Polymers Based On N-Containing Carboxylic Acid Ligands

In this paper, by tuning reaction time and in situ decomposition of ligand, fifty-five coordination polymers （CPs） were synthesized under hydrothermal conditions by using copper and lanthanide ions as central metals, 2,5-bis（carboxymethylmercapto）-1,3,4-thiadiazole acid （H₂bct） and pyridine-2,3-dicarboxylic acid （2,3-H₂pydc） as main ligands, and N,N’-di（4H-1,2,4-triazole）butanamide （dtb） and succinic acid （H₂suc） as auxiliary ligands, namely, Ln^â…¢Cu^â…¡CuⅠ（bct）3（H₂O）2 [Ln=La （1）, Ce （2）, Pr （3）, Nd （4）, Sm （5）, Eu （6）, Gd （7）, Tb （8）, Dy （9）, Er （10）, Yb （11）, and Lu （12）], Lnâ…¢CuⅠ（bct）2 [Ln= Ce （2a）, Pr （3a）, Nd （4a）, Sm （5a）, Eu （6a）, Gd （7a）, Tb （8a）, Dy （9a）, Er （10a）, Yb （lla）, and Lu （12a）], Lnâ…¢2（bct）3（H₂O）5 [Ln=La （1b）, Ce （2b）, Pr （3b）, Nd （4b）, Sm （5b）, Eu （6b）, Gd （7b）, Tb （8b）, and Dy （9b）], [Ln^â…¢Cu^Ⅱ（2,3-pydc）2（suc）0.5（H₂O）3]·H₂O [Ln=La （13）, Pr （14）, Nd （15）, Sm （16）, Gd （17）, and Eu （18）], [Lnâ…¢2Cuâ…¡3（2,3-pydc）6（H₂O）10]·8H₂0 [Ln=Eu （19）, Tb （20）, Dy （21）, and Er （22）], [Lnâ…¢2CuⅡ（2,3-pydc）2（suc）（μ2-OH）2（H₂O）2]·2H₂O [Ln=Er （23）, Yb （24）, and Lu （25）], [Lnâ…¢2CuⅡ（2,3-pydc）2（suc）2（H₂O）6]·2H₂O [Ln=Nd （26）, Sm （27）, Eu （28）, Gd （29）, Tb （30）, Dy （31）, and Er （32）], and Lnâ…¢2CuⅡ（2,3-pydc）2（suc）2（H₂O）2 [Ln=Er （33）, Yb （34）, and Lu （35）]. They were characterized by X-ray single-crystal diffraction, elemental analysis, IR, X-ray powder diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The photoluminescence and magnetic properties of partial CPs were measured by fluorescence spectrometer and magnetometer.X-ray single-crystal diffraction analysis reveals that CPs 1-12 possess a unique one-dimensional （1D） strip-shaped structure containing two types of double-helical chains and a double-helical channel. CPs 2a-12a show a three-dimensional （3D） framework formed by Cuâ…  linking two types of homochiral layers with double-helical channels. CPs lb-9b exhibit a 3D framework with single-helical channels. In 13-18, the dinuclear Cu2（2,3-pydc）4 and Ln2（COO）2 units link each other to form two-dimensional （2D） layers, which are extended by the suc anions into a 3D framework. In 19-22, the lanthanide ions connect the 2D supramolecular layers derived from trinuclear Cu3（2,3-pydc）6 units into a 3D framework. In 23-25, the mononuclear Cu（2,3-pydc）2 units bridge the1D lanthanide chains into 2D layers, which are linked by the suc anions into a 3D framework. CPs 26-32 and 33-35 show similar 2D layer structrues, respectively.The solid state fluorescent measurement exhibits that CPs 6b and 8b display red and green luminescence of Euâ…¢ and Tbâ…¢ ions sensitized by bct ligand, respectively, and microsecond-level lifetimes. Magnetic measurement indicates that CP 8b manifests a rare magnetic transition of short-range ferromagnetic ordering at 110 K and a long-range ferromagnetic ordering below 10 K. CPs 9a and 9b are indicative of field-induced single chain magnet （SCM） and/or single molecule magnet （SMM） behaviors, with Ueff values of 51.7 and 36.5 K, respectively. CP 21 is indicative of a field-induced SMM behavior with a Ueff value of 83.7K.