Construction of metal–organic frameworks with transitional metals based on the 3,5-bis(4-pyridyl)-1H-1,2,4-triazole ligand

Based on the versatile ligand 3,5-bis(4-pyridyl)-1H-1,2,4-triazole (Hbpt) derived from an in situ metal/ligand reaction, a series of coordination compounds CoCl₄(H₃bpt)(H₂O) (1), Cu(H₂bpt)₂(SO₄)₂(H₂O)₆ (2), [Ag(bpt)]_n (3), [Co(Hbpt)(pa)]_n (4), [Co(Hbpt)(pda)]_n (5) and [Cu(Hbpt)(pda)(H₂O)]_n (6) have been constructed (pa = phthalate, pda = 1,3-phenylenediacetate). The structures of these targeted complexes have been characterized by X-ray single-crystal diffraction techniques. Structural analysis reveals that Hbpt adopts versatile coordination modes to arrange the metal ions in 0-D point, simple (4,4) layers and dinuclear core chains in 1–3, which are further extended via the benzenedicarboxylate connectors to give rise to a variety of coordination networks such as (4,4), (4¹² · 6³), (6⁴ · 8²) topologies in 4–6. The supramolecular organization through hydrogen bonds is analyzed for these complexes and thermal stability of these crystalline materials has been explored by TG-DTG.     

Hydrothermal synthesis, thermal and luminescent investigations of lanthanide(III) coordination polymers based on the 4,4′-oxybis(benzoate) ligand

In this study, new series of lanthanide 4,4??-oxybis(benzoates) of the general formula Ln₂oba₃·nH₂O, where Ln = lanthanides from La(III) to Lu(III), oba?=?C₁₂H₈O(COO) ₂ ^2? and n?=?3?C6, has been prepared under hydrothermal conditions. The compounds were characterized by elemental analysis, infrared spectroscopy, X-ray diffraction patterns measurements and different methods of thermal analysis (TG, DSC, and TG-FTIR). In addition, photoluminescence properties of the selected complexes have been investigated. Crystalline compounds are isostructural in the whole series. Both carboxylate groups are deprotonated and engaged in the coordination of Ln(III) ions. Heating of the complexes leads to the dehydration and next decomposition processes. Although of the same structure, the removal of water molecules proceeds in different ways. In the nitrogen atmosphere, they decompose releasing water, carbon oxides and phenol molecules. The complexes of Eu(III), Tb(III) and Dy(III) exhibit photoluminescence in the visible range, whereas the compounds of Nd(III) and Yb(III) in the near-infrared region upon excitation by UV light.     

Six lanthanide(III) coordination polymers with 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole: syntheses,structures, and photoluminescence

Six 3-D lanthanide(III)-metal-organic frameworks (MOFs) through multidentate 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole (H₂BCPT); acetic acid (HOAc); and corresponding trivalent rare earth chloride, {[Ln(BCPT)(OAc)(H₂O)]·(H₂O)}_n (Ln = Nd³⁺ (1); Sm³⁺ (2), Gd³⁺ (3), Tb³⁺ (4), Ho³⁺ (5), Yb³⁺ (6)), have been synthesized. MOFs 1–6 were characterized via FT-IR spectroscopy, elemental analysis, X-ray single-crystal diffraction, thermal analysis, and fluorescence. MOFs 1–6 are isomorphous, which can be described as a 3-D construction containing a dinuclear cluster [Tb₂(CO₂)₂(O)₂]. The 3-D structure with (4,4) topologies have been extended through BCPT^2? using μ₄-kO;kO;kO;kO coordination modes. Solid-state luminescence of 1–4 and 6 shows the characteristic bands of Nd³⁺, Sm³⁺, Tb³⁺, and Yb³⁺ from visible to near-infrared spectral regions.     

Influence of the counteranion on silver(I)–dithioether coordination polymers

In order to rationalize the effect of the size and coordinating ability of counteranions upon the structure of Ag(I)–dithioether coordination polymers, a series of such polymers has been synthesized by the combination of the 1,3-bis(methylthio)propane building block and AgX silver salts (X = ClO₄⁻ (1), BF₄⁻ (2), CF₃SO₃⁻ (3), SbF₆⁻ (4), C₆H₅COO⁻ (5), CF₃COO⁻ (6), CF₃CF₂CF₂COO⁻ (7) and ⁻OOCCF₂CF₂COO⁻ (8)). Except in two cases, all complexes form 1D-coordination polymers.     

Thiophene based europium β-diketonate complexes: effect of the ligand structure on the emission quantum yield

The synthesis and the molecular and photophysical characterization, together with solid state and solution structure analysis, of a series of europium complexes based on β-diketonate ligands are reported. The Eu(III) complex emission, specifically its photoluminescence quantum yield (PL-QY), can be tuned by changing ligands which finely modifies the environment of the metal ion. Steady-state and time-resolved emission spectroscopy and overall PL-QY measurements are reported and related to geometrical features observed in crystal structures of some selected compounds. Moreover, paramagnetic NMR, based on the analogous complexes with other lanthanides, are use to demonstrate that there is a significant structural reorganization upon dissolution, which justifies the observed differences in the emission properties between solid and solution states. The energy of the triplet levels of the ligands and the occurrence of nonradiative deactivation processes clearly account for the luminescence efficiencies of the complexes in the series.     

Polycarboxylate-assisted assembly of cobalt(II) metal–organic coordination polymers from a “V”-shaped tri-pyridyl-bis-amide ligand

The aim of this study was to explore the influence of the position and angles of carboxyl groups of polycarboxylates on constructing coordination polymers. Three Co(II) metal–organic coordination polymers based on a tri-pyridyl-bis-amide ligand, namely [Co(L)(1,2-BDC)(H₂O)₂]·2H₂O (1), [Co(L)(1,4-BDC)(H₂O)₂]·2H₂O (2) and [Co(L)₂(BTEC)_0.5]·H₂O (3) (L = N,N′-bis(pyridine-3-yl)pyridine-2,6-dicarboxamide, 1,2-H₂BDC = 1,2-benzenedicarboxylic acid, 1,4-H₂BDC = 1,4-benzenedicarboxylic acid, H₄BTEC = 1,2,4,5-benzenetetracarboxylic acid), have been obtained by tuning the auxiliary polycarboxylate ligands. Structural analyses reveal that complexes 1–3 display diverse structures. Complex 1 displays a meso-helical chain linked by L ligands, which is further extended into a three-dimensional supramolecular framework through hydrogen-bonding interactions. The 1,2-BDC with a chelating coordination mode only acts as the hydrogen bond acceptor. In complex 2, the 1,4-BDC anions connect adjacent Co(II) atoms to form a linear chain, which is connected by hydrogen-bonding interactions to construct a 3D supramolecular network. Complex 3 exhibits a chain, which is composed of left-/right-handed Co-L helical chains and Co-BTEC linear chain. The 1D chains are ultimately extended into a two-dimensional supramolecular network by hydrogen-bonding interactions. Moreover, the thermal stability and the fluorescent properties of the title complexes and the electrochemical behaviors of a bulk-modified carbon paste electrode with complex 2 have been investigated at room temperature.     

Crystal Structure and Spectra Characters of 2-Benzoly-3-(4-(1,2,4-triazole)-5-anilino-thiophene and 2-(4-Methyl-benzoly)-3-(4- chlrolphenyl)-3-(1,2,4-triazole)-5-anilino-thiophene

Triazole derivatives are widely studied, because they represent the largest group of modern fungicides and are widely used both in human and veterinary therapy and in agriculture. We synthesized the title compound in which the thiophene ring was substituted by a 1,2,4-triazole group, a phenacyl group, a phenylaminol group and a benzene ring.     

Annelation of the 1,2,4-triazole ring on the basis of α-hydrazino-substituted heterocycles and their hydrazones (review)

The literature data on methods for the synthesis of annelated 1,2,4-triazole systems on the basis of -hydrazino-substituted heterocycles and their hydrazones are correlated, and their chemical properties and biological activity are examined briefly.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1587–1613, December, 1993.     

Synthesis and characterization of two- and three-dimensional coordination polymers built with 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole and/or 1,4-bis(imidazol-1-ylmethyl)benzene

Two new coordination polymers, [Cd(bct)(H₂O)]·(H₂O) (1) and [Zn(bct)(bip)]·2(H₂O) (2) (H₂bct?=?3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole, bip?=?1,4-bis(imidazol-1-ylmethyl)benzene), have been synthesized. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectroscopy, and thermogravimetric analysis. Compound 1 is a two-dimensional structure with double-layered network, where bct ligands adopt a μ ₄ -k ¹,k ¹,k ¹,k ¹ bridging mode linking four five-coordinate Cd ions. Compound 2 exhibits a three-dimensional framework consisting of double-layered helical chains with the bct and bip adopting μ ₃ -k ¹,k ¹,k ¹ and μ ₂ -k ¹,k ¹ bridging mode, respectively. Complexes 1 and 2 exhibit intense emissions at 399 and 441?nm, respectively.     

Syntheses,crystal structures,and luminescent properties of three metal coordination polymers based on adipic acid and 2-(pyridine-3-yl)-(1H)-benzimidazole

Three new metal coordination polymers constructed from adipic acid and 2-(pyridin-3-yl)-(1H)-benzimidazole ligands, [M(ADP)(3PBI)₂(H₂O)₂]·2H₂O (M = Ni and Co for 1 and 2, respectively) and [Cd(ADP)(3PBI)(H₂O)] (3) [ADP = adipic acid dianion; 3PBI = 2-(pyridin-3-yl)-(1H)-benzimidazole], have been synthesized by hydrothermal reactions and were characterized by X-ray single-crystal diffraction, elemental analyses, IR, powder X-ray diffraction, and thermogravimetry. Complexes 1 and 2 are isostructural. Both form a 1-D linear chain structure, which is further assembled into a 3-D supramolecular framework by π?π stacking and hydrogen bonding interactions. Complex 3 possesses a binuclear unit and displays a 2-D layer which is further extended to a 3-D supramolecular architecture via hydrogen bonding and other weak packing interactions. The luminescent properties of 3 were investigated in the solid state at room temperature.     

Synthesis and Crystal Structure of 4-Salicylimine-3,5-bis(2-hydroxyphenyl)-1,2,4-triazole

1 INTRODUCTION 1, 2, 4-Triazole and its derivatives have gained great attention as ligands to transition metals by the fact that they unite the coordination geometry of both pyrazoles and imidazoles, and in addition exhibit a strong and typical property of acting as bridging ligands between two metal centers. In this bridging capacity, the 1, 2, 4-triazole ligands show a great coordination diversity, especially when the triazole nucleus are substituted with additional donor groups[1]. In…     

Variations of structures on changing the ratios of metal ions in rare Ca(II)–Zn(II) hetero-metallic self-assembled coordination polymers of hexamethylenetetramine and benzoate

Two rare hetero-metallic calcium(II)-zinc(II) complexes [CaZn₄(OBz)₁₀(μ₂-hmt)₂]_n (1) and [Ca₂Zn₄(OBz)₁₂(μ₂-hmt)₂]_n (2) have been synthesized using basic zinc carbonate, benzoic acid (HOBz), hydrated calcium chloride and hexamethylenetetramine (hmt) by varying the molar ratio of the reactants. Both the complexes have been analyzed by elemental analysis, IR spectroscopy and X-ray crystallography. The complex 1 is a 1D polymer which contains one calcium ion and four zinc atoms in the asymmetric unit together with ten benzoates and two hmts. The polymer has been constructed by the alternate joining of paddle-wheel Zn₂(OBz)₄ units and Zn₂Ca trinuclear species by μ₂-hmt bridging molecules connecting Zn²⁺ ions. Zinc atoms have five coordinate square pyramidal geometries and four coordinate tetrahedral geometries in Zn₂(OBz)₄ and Zn₂Ca moieties, respectively, whereas calcium atoms have six-coordinate distorted octahedral geometry. Complex 2 is also a 1D polymer but unlike complex 1, it contains four independent zinc and two independent calcium atoms in the asymmetric unit together with twelve benzoates and two hmts. By contrast, the polymeric structure of complex 2 has been formed by the connection of Zn₂Ca trinuclear species via μ₂ hmt bridging molecules at Zn centers. Complex 2 is also a 1D polymer but unlike complex 1, it contains four independent zinc and three independent calcium atoms in the asymmetric unit together with twelve benzoates and two hmts. All four zinc atoms are four coordinate with tetrahedral environments and the calcium atoms are six coordinated (two are located on a center of symmetry) exhibiting a distorted octahedral geometry.     

Two Zn(II) coordination polymers based on 1,3-di(4’-carboxyl-phenyl)benzene and N-donor coligands: syntheses,crystal structures,and luminescent properties

Two coordination polymers, {[Zn(dpb)(3-bpmp)_0.5]·1.5(DMF)}_n (1) and [Zn(dpb)(4-bpmp)]_n (2) (H₂dpb = 1,3-di(4′-carboxyl-phenyl)benzene, 3-bpmp = 1,4-bis(3-pyridylmethy)piperazine, 4-bpmp = 1,4-bis(4-pyridylmethy)piperazine and DMF = N,N-dimethylformamide), were solvothermally synthesized and characterized. Tuning the difference of N-donor ligands, we obtained 1 and 2 which display different topological nets. Complex 1 features a 6-connected topological net and 2 shows a 4-connected three-fold interpenetrated framework. Luminescent properties of 1 and 2 are investigated at room temperature.     

Two novel interpenetrated zinc(Ⅱ) and cadmium(Ⅱ) coordination polymers based on 4-imidazole-benzoate:Syntheses,crystal structures and properties

Two novel interpenetrated coordination polymers,[Zn(IBA)2]n (1) and {[Cd(IBA)2(H2O)].4H2O}n (2),have been synthesized by using 4-imidazole-benzoic acid (HIBA) as ligand under hydrothermal conditions. Complex 1 crystallizes in a chiral space group and has a two-fold interpenetrated 2D network structure with (4,4) topology,while complex 2 is a 3D porous dia network with four nets interpene-trating each other. The SHG activity of 1 and the photoluminescent property of 2 have been investigated.     

Studies on the crystal structure and characterization of N-(4-acetylphenyl)-N’-(2-nitrobenzoyl)-thiourea

N-(4-acetylphenyl)-N′-(2-nitrobenzoyl)-thiourea has been synthesized in high yield under PEG-400 as the phase-transfer catalyst and its the compound structure was determined by single crystal X-ray diffraction. The compound is also a considerable plant-growth regulator. In addition, the compound L exhibited selective recognition for Hg²⁺ over other metals ions such as Ag⁺, Ca²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺, and Mg²⁺ in DMSO solutions.     

Synthesis and crystal structure of two coordination polymers based on N,N′-bis(3-pyridylmethyl)pyromellitic diimide and fluorescence thiocyanate sensing

Transition Metal Chemistry - Two N,N′-bis(3-pyridylmethyl)pyromellitic diimide (3-pmpmd) coordination polymers, namely{[Hg(3-pmpmd)I2]·H2O)}n (1), {[Ni2(3-pmpmd)3 (NO3)4]·2CH3OH}n...     

Influence of the size of aromatic chelate ligands on the one-dimensional structures of copper(II) 4,4′-oxy-bis(benzoate) coordination polymers

Two one-dimensional coordination polymers, [Cu(Oba)(TATP)] _n · nH₂O (I) and [Cu(Oba)(DPPZ)(H₂O)]n · nH₂O (II) (Oba is 4.4′-oxy-bis(benzoate), TATP is 1,4,8,9-tetranitrogen-tris(phene), DPPZ is dipyrido[3,2-a:2′,3′-c]phenazine), have been synthesized under similar conditions and structurally characterized by elemental analysis, IR spectra, and X-ray crystal structure. Compounds I and II are based on topologically identical chains, where the copper centers chelated by the amine ligands are linked by the Oba bridges, as well as the coordination modes of the Oba ligands. However, the angles between the individual links and the environment of the copper centers are substantially different between the two compounds and were found to be primarily influenced by the sizes of the rigid aromatic chelate ligands. The article is published in the original.     

New π-conjugated polymers based on N-(4-(3,5-bis(4-bromophenyl)-[1,2,4]triazol-4-yl)-phenyl)carbazole: Synthesis and photoluminescent, electroluminescent, and electrochromic properties

New π-conjugated copolyfluorenes carrying main-chain electron-acceptor triazole groups and side-chain electron-donor carbazole fragments are synthesized. All copolymers show solubility in common organic solvents and exhibit high thermal stability and excellent film-forming behavior. The absorption, photoluminescent, electroluminescent, and electrochromic properties of the copolymers are investigated. Polymer films feature stable electrochromic properties as their color changes from yellow in the neutral from to lilac in the oxidized form during a change in the applied voltage from 0 to 1.9 V. In addition, copolyfluorenes demonstrate better electroluminescent properties than the standard homopolylfluorene and offer promise as attractive electroactive materials for use as emitting layers in polymer light-emitting devices.     

Probing the intrinisic structure and dynamics of aminoborane coordination at late transition metal centers: mono(σ-BH) binding in [CpRu(PR3)2(H2BNCy2)]+

Aminoboranes, H(2)BNRR', represent the monomeric building blocks from which novel polymeric materials can be constructed via metal-mediated processes. The fundamental capabilities of these compounds to interact with metal centers have been probed through the coordination of H(2)BNCy(2) at 16-electron [CpRu(PR(3))(2)](+) fragments. In contrast to the side-on binding of isoelectronic alkene donors, an alternative mono(σ-BH) mode of aminoborane ligation is established for H(2)BNCy(2), with binding energies only ~8 kcal mol(-1) greater than those for analogous dinitrogen complexes. Variations in ground-state structure and exchange dynamics as a function of the phosphine ancillary ligand set are consistent with chemically significant back-bonding into an orbital of B-H σ* character.     

Three-dimensional metal–organic frameworks: Two Ag(I) coordination polymers of TTF derivatives with axially chiral helical motifs

Two novel 3D coordination polymeric networks based on Ag(I) and TTF derivatives, [Ag₄(tces-TTF)₂(CF₃SO₃)₂](CF₃SO₃)₂ (tces = 2,3,6,7-tetra(cyanoethylsulfanyl)) (1) and [Ag₂(bmdt)₂](SbF₆)₂ · acetone (bmdt = 4,5-bis(methylsulfanyl)-1,3-dithiole-2-thione) (2), were synthesized and crystallographically characterized. Both 1 and 2 have axially chiral helical motifs and these helices were assembled in a similar way: spiral up along b axis infinitely. In addition, complex 2 forms a “cds” network with a topology of 6⁵.8. The conductivity of complex 1 was measured at RT with a σ value of 3.47 × 10⁻⁶S cm⁻¹ due to the S?S contacts in the molecules, while 2 is an insulator at RT.