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Temperature dependent 3D structures of lanthanide coordination polymers based on dicarboxylate mixed ligands


Fourteen three-dimensional (3D) lanthanide coordination polymers (CPs) with dicarboxylate mixed ligands, [Ln(fum)1.5(H2O)2]∙0.5(H2bdc)∙H2O (Ln = Sm (1), Tb (2)), [Ln2(fum)2(bdc)(H2O)4]∙2H2O (Ln = Sm (3), Eu (4), Tb (5), Er (6)), [Ln(fum)0.5(bdc)] (Ln = Sm (7), Eu (8), Tb (9), Er (10)), and [Ln2(bdc)2(ox)(H2O)4]·0.7H2O (Ln = Sm (11), Gd (12), Tb (13), Dy (14)) have been synthesized hydrothermally from the self-assembly of lanthanide(III) ions (Ln3+), fumaric acid (H2fum), and terephthalic acid (H2bdc) in the presence of potassium hydroxide at different temperatures. The compounds fall into four classes. Compounds 1 and 2 were isolated from hydrothermal reactions performed at a relatively low temperature of 100 °C and found to crystallize in the triclinic space group P-1. The 3D framework is assembled from 2D layers of [Ln(fum)(H2O)2] units pillared by the chelating fum ligands having 1D rhombic channels templated by H2bdc and lattice H2O molecules. The framework presents a binodal (4,5)-connected tcs topology with the point symbol of (44.62)(44.66). Raising the reaction temperature to 140 °C resulted in the formation of compounds 3-6. These materials crystallize in the monoclinic system with the polar space group P21 and feature a 3D network constructed from dinuclear {Ln2(OCO)6(H2O)4} units interlinked by fum and bdc ligands, showing a uninodal 6-connected two-fold interpenetrated pcu topology. The small channels of the framework are occupied by lattice H2O molecules. Further increase of the reaction temperature to 160 °C gave rise to the formation of compounds 7-10, crystallizing in the orthorhombic space group Pbca. The 3D framework is generated from the 2D corrugated sheets of [Ln(fum)]2+ bound by the bdc ligands and contains no crystallization H2O molecules in the lattice. The framework possess a trinodal (4,6,7)-connected net with the point symbol (42.64)2(46.68.8)(412.69)2. Finally, compounds 11-14 contained in situ generated oxalate (ox) ligand formed under the hydrothermal conditions conducted at a high reaction temperature of 180 °C. These compounds crystallize in the monoclinic space group P21/c and posses a 3D open-framework consisting of a dinulclear [Ln2(ox)(H2O)4]2+ unit linked by bridging bdc ligands having small void channels occupied by lattice H2O molecules. The frameworks were topologically simplified as a binodal (4,5)-connected tcj/hc with total point symbol of (42.52.72)(42.53.75). In the solid state at room temperature, the Tb-(2, 5, 9, and 13) and Eu-(4 and 8) compounds emit green and red light, respectively.

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Publication details

The article was received on 24 Aug 2018, accepted on 25 Sep 2018 and first published on 26 Sep 2018

Article type: Paper
DOI: 10.1039/C8CE01430B
Citation: CrystEngComm, 2018, Accepted Manuscript
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    Temperature dependent 3D structures of lanthanide coordination polymers based on dicarboxylate mixed ligands

    K. Chainok, N. Ponjan, C. Theppitak, P. Khemthong, F. Kielar, W. Dungkeaw, Y. Zhou and S. R. Batten, CrystEngComm, 2018, Accepted Manuscript , DOI: 10.1039/C8CE01430B

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