Alkali and alkaline earth coordination polymers constructed from benzene-1,2,4,5-tetracarboxylic acid and flexible dicarboxylate acid ligands: syntheses, structures and spectroscopic and thermal properties

Two new metal coordination complexes, namely, poly[aqua(μ₆-benzene-1,2,4,5-tetracarboxylic acid-κ⁸O¹:O¹,O²:O^2':O⁴:O⁴,O⁵:O^5')(μ-but-2-enedioato-κ²O¹:O⁴)potassium(I)], [K₂(C₄H₂O₄)(C₁₀H₆O₈)(H₂O)₂]_n or [K₂(fum)(H₄btec)(H₂O)₂]_n, (1), and poly[aqua(μ₈-2,5-dicarboxybenzene-1,4-dicarboxylato-κ¹²O¹:O^1',O²:O²,O^2':O^2':O⁴:O^4',O⁵:O⁵,O^5':O^5')(μ-ethanedioato-κ⁴O¹,O²:O^1',O^2')strontium(II)], [Sr₂(C₂O₄)(C₁₀H₄O₈)(H₂O)₂]_n or [Sr₂(ox)(H₂btec)(H₂O)₂]_n, (2) (H₄btec = benzene-1,2,4,5-tetracarboxylic acid, H₂btec = 2,5-dicarboxybenzene-1,4-dicarboxylate, fum = fumarate and ox = oxalate), have been obtained under hydrothermal conditions by reacting the different alkali and alkaline earth metal salts with H₄btec, fumaric acid (H₂fum) and oxalic acid (H₂ox). Complexes (1) and (2) were structurally characterized by single-crystal X-ray diffraction, IR and UV-Vis spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetic analysis-differential scanning calorimetry (TGA-DSC). Complex (1) displays a two-dimensional (2D) layer with the K⁺ ion in a distorted pentagonal bipyramidal geometry and exhibits a uninodal 6-connected hxl/Shubnikov plane net (3,6) with {3⁶.4⁶.5³} topology. Complex (2) displays a three-dimensional (3D) network structure, in which the Sr²⁺ ion is in a distorted monocapped square antiprism geometry. The framework possess a binodal (5,8)-connected net with the Schläfli symbol {3².4¹⁰.5⁸.6⁴.7⁴}{3².4⁶.5²}₂. The 3D Hirshfeld surfaces and 2D fingerprint plots show that the main interactions are the O...H/H...O intermolecular interactions. Moreover, the thermal decompositions of (1) and (2) in the temperature range 303-1273 K revealed that they both decompose in three steps and transform to the corresponding metal oxide.

Formation of a robust, double-walled LiMOF from an L-shaped di-substituted N-heterocyclic adamantane-based ligand

The properties of adamantane render it an attractive building block towards the synthesis of robust frameworks. This work describes the synthesis of the L-shaped 1,3-bis(3'-carboxypyridine)adamantane (L1) ligand and the corresponding Li(i), Zn(ii) and Cu(ii) frameworks. Three topologically analogous Li(i) frameworks LiMOF12, LiMOF30 and LiMOF50 are reported, with calculated solvent accessible void volumes of 46, 43 and 36%, respectively. The reaction between the carboxylate groups of L1 and the Li(i) cations resulted in the formation of Li-carboxylate rods. The Li-carboxylate rods contributed to the formation of a double-walled MOF with large, open one dimensional channels. The synergistic effect of the double wall, lithium-carboxylate rods and the adamantane core itself, resulted in the formation of a robust network stable up to temperatures of 300-350 °C and a minimum of three months stability in air. Furthermore, complexation of L1 with Cu(BF4)2·H2O and Zn(CF3SO3)2 provided a 2D → 3D interpenetrated network containing a classic dimeric copper paddle-wheel SBU, and an infinite 1D chain which extended into a 3D structure facilitated by hydrogen-bonding interactions, respectively.

Synthesis, Structures and Electrochemical Properties of Lithium 1,3,5-Benzenetricarboxylate Complexes

Four lithium coordination polymers, [Li₃(BTC)(H₂O)₆] (1), [Li₃(BTC)(H₂O)₅] (2), [Li₃(BTC)(μ₂-H₂O)] (3), and [Li(H₂BTC)(H₂O)] (4) (H₃BTC = 1,3,5-benzenetricarboxylatic acid), have been synthesized and characterized. All the structures have been determined using single crystal X-ray diffraction studies. Complexes 1 and 2 have two-dimensional (2-D) sheets, whereas complex 3 has three-dimensional (3-D) frameworks and complex 4 has one-dimensional (1-D) tubular chains. The crystal-to-crystal transformation was observed in 1⁻3 upon removal of water molecules, which accompanied the changes in structures and ligand bridging modes. Furthermore, the electrochemical properties of complexes 3 and 4 have been studied to evaluate these compounds as electrode materials in lithium ion batteries with the discharge capacities of 120 and 257 mAhg-1 in the first thirty cycles, respectively.

A Highly Water-Tolerant Magnesium(II) Coordination Polymer Derived from a Flexible Layered Structure

A two-dimensional (2D) layered Mg(II) coordination polymer (CP) with a high tolerance for H2 O was designed, synthesised, and crystallographically characterised. The synthesis was achieved by the introduction of a flexible 2D layered structure composed of Mg(II) ions and isonicotinate N-oxide ligands. Owing to its high H2 O tolerance, the obtained 2D layered structure has the flexibility to repeatedly adsorb a large amount of H2 O associated with interlayer expansion and enable the removal of H2 O from a H2 O/2-propanol mixed vapour. These results indicate that the CP could be an excellent dehydrating agent.

Evaluation of structural transformation in 2D metal–organic frameworks based on a 4,4′-sulfonyldibenzoate linker: microwave-assisted solvothermal synthesis, characterization and applications

Structural transformation has been observed in 2D MOFs.

Two sodium(I) coordination polymers constructed by the V-shaped ligands 2,2'-[isopropylidenebis(1,4-phenyleneoxy)]diacetic acid and 2,2'-[sulfonylbis(1,4-phenyleneoxy)]diacetic acid

Two new inorganic-organic coordination polymers, namely poly[[μ6-2-(4-{1-[4-(carboxymethoxy)phenyl]-1-methylethyl}phenoxy)acetato][μ4-2-(4-{1-[4-(carboxymethoxy)phenyl]-1-methylethyl}phenoxy)acetato]disodium(I)], [Na2(C19H19O6)2]n, (I), and poly[hexa-μ-aqua-diaquabis{μ3-2,2'-[sulfonylbis(1,4-phenyleneoxy)]diacetato}tetrasodium(I)], [Na4(C16H14O8)2(H2O)8]n, (II), have been prepared. In (I), the asymmetric unit contains two Na(I) cations and two 2-(4-{1-[4-(carboxymethoxy)phenyl]-1-methylethyl}phenoxy)acetate (HL1(-)) ligands. Each Na(I) cation is octahedrally coordinated by two ether O atoms and four carboxylate O atoms of three different HL1(-) ligands. The NaO6 polyhedra share edges to form an inorganic ribbon along the a axis. These inorganic ribbons are further connected by the HL1(-) ligands to generate two-dimensional layers parallel to the (001) plane. The structure of (II) consists of ribbons of four crystallographically independent Na atoms (three six- and one five-coordinate), which are bridged by carboxylate O atoms of 4,4'-[sulfonylbis(1,4-phenyleneoxy)]diacetate (L2(2-)) ligands and water molecules. These ribbons are interlinked by L2(2-) ligands through two different coordination modes to afford a three-dimensional network.

Synthesis, Crystal Structure, and Luminescence Properties of a New Calcium(II) Coordination Polymer Based on L-Malic Acid

A new calcium coordination polymer [Ca(HL-MA)]n(H3L-MA = L-malic acid) has been solvothermally synthesized. The structure of the newly synthesized complex has been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, reflectance UV-Vis & IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). The single crystal structure analysis showed that the complex forms three-dimensional framework. The new Ca(II) complex has displayed very high thermal stability which was inferred from TGA and PXRD results. As far as the optical property of the new complex is concerned, the complex emitted its own characteristic sensitized luminescence.