Crystal structures and gas adsorption behavior of new lanthanide-benzene-1,4-dicarboxylate frameworks

Six new lanthanide metal organic complexes, i.e. [La2(NO2-BDC)3(H2O)4] (1) [Ln(L)0.5(NO2-BDC) (H2O)]·3H2O (Ln = Eu (2), Tb (3), Dy (4) and Ho (5); L = BDC2− or BDC2−/NO2-BDC2-) and [Tm(NO2-BDC)1.5(H2O)]·H2O (6), have been synthesized using mixed ligands of benzene-1,4-dicarboxylic acid (H2BDC) and the in situ generated 2-nitro-benzene-1,4-dicarboxylic acid (NO2-BDC2-). Single crystal structures and topologies of the complexes are presented based on the single crystal X-ray diffraction and spectroscopic data. Whilst the structures of 1 and 6 contain negligible voids, the frameworks of 2–5 are microporous in nature and stable upon the removal of all the water molecules from the structures and thermal treatment to over 400 °C. Based on the study of 2, significant adsorption capacities for carbon dioxide (95 cm3·g−1 or 4.2 mmol·g−1) and hydrogen (79 cm3·g−1 or 4 mmol·g−1), as well as the remarkable stability of the framework upon the sorption/desorption experiments are revealed

A series of new microporous lanthanide frameworks [Ln(C8H3NO6)(L)0.5(H2O)]·3H2O (Ln = Pr, Nd, Sm and Gd, and L = C8H4O4or C8H4O4/C8H3NO6): Syntheses, characterization and photoluminescence properties

Four new microporous lanthanide coordination polymers of general formula [Ln(C8H3NO6)(L)0.5(H 2O)]·3H2O (Ln = Pr, Nd, Sm and Gd, and L = C 8H4O4 or C8H4O 4/C8H3NO6) were hydrothermally synthesized using in situ ligand synthesis. The complexes are isostructural featuring the NbO type framework, which is constructed from chains of edge-sharing {LnO9} polyhedra. The one-dimensional channel extending in the [1 0 0] direction with an aperture of approximately 4 × 8 Å2 houses water of crystallization, which are ordered in edge-shared pentagons by hydrogen bonding interactions. Evidence for the significance of the hydrogen bonding interactions in stabilizing the framework is presented. Crystallographic disorder in the organic ligands, including rare substitutional disorder, is described. The complexes show type I gas sorption isotherms characteristic of microporosity, and are thermally stable up to approximately 400 °C. The solid state luminescence properties of these complexes are included. © 2014 Elsevier Ltd. All rights reserved

Structural Variation and Preference in Lanthanide-pyridine-2,6-dicarboxylate Coordination Polymers

Ten lanthanide coordination polymers were designed and synthesized using pyridine-2,6-dicarboxylic acid (H₂pdc) and two different heating techniques (conventional and microwave): [Ln­(pdc)­(H₂O)₄]₃­·3Cl {<i>Pa</i>3̅; Ln = Pr (<b>I</b>), Nd (<b>II</b>), Sm (<b>III</b>), Eu (<b>IV</b>), and Gd (<b>V</b>)}, [Ln­(pdc)­(Hpdc)­(H₂O)₂]­·3H₂O {<i>P</i>2₁/<i>c</i>; Ln = Pr (<b>VI</b>), Nd (<b>VII</b>), and Sm (<b>VIII</b>)} and [Ln­(pdc)­(H₂O)₄]₃­·3Cl {<i>Ia</i>3̅; Ln = Sm (<b>IX</b>), and Eu (<b>X</b>)}. These complexes show variation in structures depending on the heating technique and the lanthanide ions. They can be classified into the cubic <i>Pa</i>3̅ (<b>I</b>–<b>V</b>) and <i>Ia</i>3̅ (<b>IX</b>, <b>X</b>), and the monoclinic <i>P</i>2₁/<i>c</i> (<b>VI</b>–<b>VIII</b>) complexes. The cubic complexes exhibit supramolecular isomerism and a tubular three-dimensional structure of interpenetrated <b>lcs</b> and <b>pcu</b> net topologies, while the monoclinic complexes are the supramolecular assemblies of the one-dimensional chains. As the cubic <i>Pa</i>3̅ structures are favored by the use of the microwave, there is variation in structures as conventional heating was employed, although the cubic <i>Pa</i>3̅ structures are still the most favored except for the <b>VI</b> case. The title complexes showed moderate thermal stabilities. The organic ligand is revealed to be a modest sensitizer to initiate the photoluminescence in the title complexes