Btec Ligand Research Articles

Syntheses, crystal structures and properties of four novel coordination polymers assembled from versatile 1,2,3,5-benzenetetracarboxylic acid

Four novel metal–organic coordination polymers constructed from 1,2,3,5-benzenetetracarboxylic acid, namely [Cu3(Hbtec)2(H2O)6]·2H2O (1), [Co2(btec)(H2O)2] (2), [Zn2(btec)(H2O)2] (3) and [Cd4(btec)2(H2O)5] (4) (H4btec=1,2,3,5-benzenetetracarboxylic acid), have been synthesized by hydrothermal methods and characterized by elemental analysis, IR, TGA and single crystal X-ray diffraction. Complex 1 is a two-dimensional double layer, while three dimensional framework structures are observed for complexes 2–4. The metal atoms are bridged via short connecting μ2-O-carboxylate atoms into dimers in the four different complexes. Interestingly, the dimers connect Hbtec bridged binuclear units into a one dimensional chain and further into a two-dimensional double layer in complex 1, while the metal ions are connected by a short bridge from μ2-O-carboxylate atoms and a long bridge from an adjacent carboxylate into a one dimensional metal carboxylate chain in complexes 2–4. In complexes 2 and 3, each btec ligand is coordinated through three metal carboxylate chains into a metal carboxylate layer, and further into a three-dimensional framework. In complex 4, both a one-dimensional single Cd-carboxylate chain as well as a one-dimensional double Cd-carboxylate chain appear, the two different chains are joined by the ligands into a three dimensional framework. The thermal stabilities and photoluminescent properties of complexes 1–4 were examined. Complexes 3 and 4 display strong room temperature photoluminescence in the visible region, which may be assigned to a ligand-to-metal charge-transfer.

One-Pot Synthesis, Crystal Structures and Thermal Properties of Two Three-Dimensional Cobalt(II) Complexes

Two cobalt(II) compounds (1) and (2) (2,2'-bipy = 2,2'-bipyridine, = 1,2,4,5-benzenetetracarboxylic acid), have been simultaneously synthesized by a one-pot slow solvent evaporation reaction. Their structures were determined by single-crystal X-ray diffraction and further characterized by X-ray powder diffraction (XRPD), IR, elemental and thermogravimetric analysis (TGA). The structural analysis reveals that compound 1 exhibits an infinite 1D chain structure with the octahedral Co(II) centers bridging by the tetrahedral ligands, while compound 2 possesses a dinuclear unit and the two adjacent octahedral Co(II) ions are linked by the bismonodentately coordinated btec ligand. Additionally, compound 2 exhibits blue fluorescent emission in the solid state at room temperature.

Poly[[hexa-μ-aqua-diaquabis(μ4-dihydrogen benzene-1,2,4,5-tetracarboxylato)magnesiumdisodium] dihydrate

The asymmetric unit of the title compound, {[MgNa2(C10H4O8)2(H2O)8]·2H2O}n, contains one octa­hedrally coordin­ated MgII atom (site symmetry 2/m), one octahedrally coordinated NaI atom (site symmetry 2) and one half of the dihydrogen benzene-1,2,4,5-tetra­carboxyl­ate (btec) ligand, the second half of the ligand being generated by a twofold rotation axis. The basic framework of the title compound features infinite (–Na–Na–Mg–)n chains along [10-1] with the metal cations bridged by the coordinating water molecules. The chains are isolated from each other by μ4-bridging btec ligands, which form inter­molecular O—H⋯O hydrogen bonds to uncoordinated water mol­ecules and the coordinated water mol­ecules of a neighbouring chain. In each btec ligand, there are also intramolecular O—H⋯O hydrogen bonds.

Syntheses and Structures of Three Copper Coordination Polymers Based on Bis(triazol‐1‐ylmethyl)benzene

AbstractThree copper(II) coordination polymers [Cu(mbtz)2(NCS)2]n (1), [Cu(mbtz)2Cl2]n (2) and [Cu(mbtz)(btec)0.5]n (3) (mbtz=1,3‐bis(1,2,4‐triazol‐1‐ylmethyl)benzene, btec=1,2,4,5‐benzenetetracarboxylate) were synthesized. In 1 and 2, two mbtz ligands are wrapped around each other and are held together by Cu(II) atoms to form one‐dimensional double chain. In 3, each btec ligand connects four Cu(II) atoms through its four carboxylate groups, resulting in a planar two‐dimensional [Cu(btec)0.5]n network. The Cu(II) atoms are further coordinated mbtz ligands to fulfil their coordination geometry and construct new [Cu(btec)0.5(mbtz)]n network. 2 and 3 further form the three‐dimensional network through the π···π stacking interactions between the mbtz ligands. The thermal stabilities of 1, 2 and 3 were measured.

Two metal–organic frameworks with unique high-connected binodal network topologies: synthesis, structures, and catalytic properties

{[Cd3(btec)(btx)0.5(μ3-OH)(H2O)]·H2O}n (1) and [Cu2(btec)(btx)1.5]n (2), two novel cadmium(II) and copper(II)-based high-connected metal–organic frameworks, with both 1,2,4,5-benzenetetracarboxylate (btec) and 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (btx) as mixed ligands were hydrothermally synthesized and structurally characterized. Both MOFs have three-dimensional (3D) structures, but different framework topologies and ligand linkage modes. 1 possesses an unprecedented binodal (4,12)-connected topology structure, in which the ligand btec serves as a rare dodecadentate and ordinary octadentate in two types of coordination modes. Meanwhile, 2 exhibits a binodal (4,7)-connected topological network with an enneadentate coordination geometry of the btec ligand. Both MOFs provide novel examples of designing and synthesizing novel binodal MOFs, and demonstrate that the 1,2,4,5-benzenetetracarboxylic acid ligand with rich coordination chemistry information is useful in the construction of binodal highly-connected nets. In addition, the catalytic performance of 2 has also been checked. 2 is active as a catalyst for the degradation of methyl orange.

Synthesis and characterization of two 3-D polymeric lanthanide complexes constructed from 1,2,4,5-benzenetetracarboxylic acid

Two new 3-D lanthanide coordination polymers, [CeK(btec)(H2O)2] n (1), [Ho(btec)0.5(ad)0.5(H2O)] n (2) (H4btec = 1,2,4,5-benzenetetracarboxylic acid, H2ad = adipic acid), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analyses reveal that both complexes crystallized in monoclinic space group P21/c and possessed 3-D net-structures. In 1, btec adopts two types of coordination modes: µ12–η2:η2:η2:η1:η2:η2:η2:η1 bridging mode linking six Ce(III) ions and six K+ ions and the other µ8–η1:η2:η2:η1:η1:η2:η2:η1 bridging mode connecting four Ce(III) ions and four K+ ions. In 2, btec adopts a µ6-bridging with each carboxylate group of btec ligand in a µ2–η1–η2 mode, the adipate is µ4-bridging with each carboxylate µ2–η1–η1-monodentate. The topological analysis shows that 1 can be simplified to a 3-nodal net with the Schläfli symbol {32,48,53,62}4{34,412,512}{438,626,82} and 2 can be simplified to a 3-nodal network with the Schläfli symbol {42,84}{46,66,83}{47,63}2. The thermogravimetric analyses and the X-ray powder diffraction of 1 and 2 are discussed.

Dissolution/Reorganization toward the Destruction/Construction of Porous Cobalt(II)− and Nickel(II)−Carboxylate Coordination Polymers

The alkali-metal-cation-induced structural transformation of porous coordination polymers (CPs), {A(2)[M(3)(btec)(2)(H(2)O)(4)]}(n) (1, A = K, M = Co; 2, A = K, M = Ni; 3, A = Cs, M = Co; and 4, A = Cs, M = Ni; btec = benzene-1,2,4,5-tetracarboxylate), occurred via a unique dissolution/reorganization process in the presence of an alkali chloride (LiCl, NaCl) in water. Treatment of 1 or 2 in an aqueous solution of LiCl resulted in the formation of new metal-carboxylate species [Co(2)(btec)(H(2)O)(10)] x H(2)O (5 x H(2)O) and {Li(2)[Ni(3)(btec)(2)(H(2)O)(10)] x 3.5 H(2)O}(n) (6 x 3.5 H(2)O), respectively. When NaCl was used in place of LiCl under similar reaction conditions, similar dissolution/reorganization processes were observed. The cobalt species 1 and 3 were converted into the metal-carboxylate product [Na(2)Co(btec)(H(2)O)(8)](n) (7), whereas the nickel-carboxylate frameworks 2 and 4 were transformed into {[Na(4)Ni(2)(btec)(2)(H(2)O)(18)] x 3 H(2)O}(n) (8 x 3 H(2)O). Single-crystal X-ray diffraction analysis revealed that 5 x H(2)O is a discrete molecule, which extends to a hydrogen-bonded 3D porous supramolecular network including tetrameric water aggregates. Compound 6 x 3.5 H(2)O adopts a 3D polymeric structure with a novel (2,4,4)-connected net on the basis of a 4-connecting organic node of a btec ligand, a square-planar 4-connecting metallic trans-Ni(O(2)C)(4)(H(2)O)(2) node, and a 2-connecting octahedral metallic trans-Ni(O(2)C)(2)(H(2)O)(4) hinge. Compound 7 possesses a 3D polymeric structure comprised of two types of intercrossed (4,4)-layers, a [Co(II)(btec)]-based layer and a [Na(I)(btec)]-based layer, in a nearly perpendicular orientation (ca. 87 degrees). Compound 8 x 3 H(2)O adopted a 2D sheet network by utilizing heterometallic trinuclear clusters of Na(2)Ni(O(2)C)(5)(H(2)O)(9) as secondary building units. Each sheet is hydrogen-bonded to neighboring units, giving a 3D supramolecular network. It is noteworthy that the dissolution/reorganization process demonstrates the cleavage and reformation of metal-carboxylate bonds, leading to a destruction/construction structural transformation of CPs.

Rational design microporous pillared-layer frameworks: syntheses, structures and gas sorption properties

The solvothermal reactions of nickel nitrate hexahydrate, aromatic carboxylic acids, and either 4,4′-bipyridine (bipy) or pyrazine (pyz) produced three open-framework compounds, namely, Ni(HBTC)(pyz)·3DMF 2 (BTC = 1,3,5-benzentricarboxylate, DMF = N,N′-dimethylformamide), Ni2(BTEC)(bipy)3·3DMF 3 (BTEC = 1,2,4,5-benzenetetracarboxylate), together with previously reported Ni(HBTC)(bipy)·3DMF 1. Compound 2 is the product when pyz pillars replace bipy pillars in the reaction of 1, and it is a 3D porous network where honeycomb grid layers constructed by Ni-BTC groups are interlinked by pyz pillars. When the BTEC ligand takes the place of BTC ligand in the system, compound 3 is obtained and it is a 3D connectivity with 1D channels where Ni-BTEC chains are interlinked by bipy ligands. The three compounds feature permanent porosity, which was confirmed by N2 adsorption isotherm measurement, and the architectural features of 1–3 can be ascribed to pillared-layer motifs. Furthermore, hydrogen adsorption measured at 77 K for 1 shows an excess uptake of 3.03 wt% at 20 bar. Details of the synthesis conditions, crystal structures and property measurements of each new compound are described.

Ionothermal synthesis and crystal structure of a 2D metal organic framework: [emim] 2[Cd 2(btec)Br 2] (emim = 1-ethyl-3-methylimidazolium, btec = 1,2,4,5-benzenetetracarboxylate)

A novel metal organic framework, namely, [emim] 2[Cd 2(btec)Br 2] ( 1) (emim = 1-ethyl-3-methylimidazolium, btec = 1,2,4,5-benzenetetracarboxylate), was synthesized in an ionothermal reaction by using an ionic liquid 1-ethyl-3-methylimidazolium bromide as solvent and template. Single-crystal X-ray diffraction reveals that the structure features an anionic two-dimensional framework with novel coordination mode of btec ligand. The imidazolium cation emim + of the ionic liquid acting as charge compensating agent intercalated into the [ Cd 2 ( btec ) Br 2 ] n 2 n - interlayers.