Syntheses,crystal structures and antibacterial activities of two new Mn(II) complexes based on triaryltriazoles

Two new Mn(II) complexes, trans-[Mn(L1-L2)₂(NCS)₂] (1–2) with triaryltriazole (1, L1 = 3-(p-bromophenyl)-4-phenyl-5-(2-pyridyl)-1,2,4-triazole; 2, L2 = 3,4-bis(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole), have been synthesized and structurally characterized by elemental analysis, FT-IR, ESI-MS, and single-crystal X-ray crystallography. Crystallographic studies revealed that both 1 and 2 contain a distorted octahedral [MnN₆] core with two trans-disposed NCS^? ions. The L1 ligand, 1 and 2, together with four known homologous Mn(II) complexes, trans-[Mn(L3-L6)₂(NCS)₂] (3–6) (3, L3 = 3-(p-methoxyphenyl)-4-(p-chlorophenyl)-5-(2-pyridyl)-1,2,4-triazole; 4, L4 = 3-(p-methoxyphenyl)-4-(p-bromophenyl)-5-(2-pyridyl)-1,2,4-triazole; 5, L5 = 3-(p-chlorophenyl)-4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole; 6, L6 = 3,5-bis(2-pyridyl)-4-(p-methylphenyl)-1,2,4-triazole), were tested in vitro for their antibacterial activities against two Gram-positive bacterial strains and two Gram-negative bacterial strains by the MTT method. The results indicate that 1 exhibited better activity than Penicillin and Kanamycin against Pseudomonas aeruginosa and also better than its free L1 ligand.     

Syntheses and crystal structures of three pillared complexes based on H2AIP and triazole-bipyridine ligands

Three pillared polymeric complexes, {[Ni₂(AIP)₂(4,4′-bpt)(H₂O)₂]·4H₂O}_n (1), {[Co(AIP)(3,3′-bpt)]·H₂O}_n (2), and {[Ni(AIP)(3,3′-bpt)]·H₂O}_n (3) (H₂AIP = 5-aminoisophthalic, 4,4′-bpt = 1H-3,5–bis(4-pyridyl)-1,2,4-triazole and 3,3′-bpt = 1H-3,5-bis(3-pyridyl)-1,2,4-triazole), have been hydrothermally synthesized and characterized by X-ray diffraction analysis. Both 1 and 3 have 2-D (6,3) honeycomb layers, which are further interlinked by bent pillared triazole-bipyridine ligands to form a bilayer structure. The structures can be simpli?ed to a (3,4)- and (3,5)-connected geometrical topology, respectively. Compound 2 has a Co-AIP layer structure in which the layers are pillared by 3,3′-bpt spacers to form the 3-D CsCl net.     

Synthesis and complexation properties of novel triazoyl-based ferrocenyl ligands

Two new ligand derivatives of ferrocene, namely N-4-[3,5-di-(2-pyridyl)-1,2,4-triazoyl]ferrocene carbimine (L1) and N-4-[3,5-di-(2-pyridyl)-1,2,4-triazoyl]ferrocene carbamide (L2), were synthesised in good yields by reacting the known compound 3,5-di-pyridine-2-yl-[1,2,4]triazol-4-ylamine (1) with ferrocenecarbaldehyde and chlorocarbonyl ferrocene, respectively. The structures of L1 and L2 were determined by X-ray crystallography. The complexation of L1 and L2 with Cu^I, Ag^I, Zn^II and Cd^II was studied by NMR and UV-vis spectroscopies, as well as by electrochemistry, with titrations used to determine metal:ligand stoichiometries. The cyclic voltammograms of L1 and L2 and their respective complexes indicated reversible one-electron transfers corresponding to the Fc^0/+ redox couple (Fc = ferrocene), with formal electrode potentials shifting to more positive values upon metal complexation.     

Syntheses,structures, and fluorescent properties of three Zn(II) and Cu(II) complexes of different ligands derived from 3,6-bis(2-pyridyl)-1,2-dihydro-1,2,4,5-tetrazine

Three supramolecular complexes [Zn(HL₁ )₂(H₂O)₂(ZnCl₄)₂] (1), [Cu(L₂ )₂Cl₂] (2), and [Zn(L₃ )Cl₂] (3) have been synthesized and characterized by single crystal X-ray diffraction analysis (L₁ = 3,5-di(2-pyridyl)-4-amino-1,2,4-triazole, L₂ = 3,5-di(2-pyridyl)-1,2,4-triazole, and L₃ = 2-pyridinecarboxylic acid (pyridin-2-ylmethylene)-hydrazide). In 1, anion–π interactions between Cl^? and the π-systems of L₁ are observed and anion–π, hydrogen bonding and π–π stacking interactions link the two complex units of [Zn(HL₁ )₂(H₂O)₂]⁴⁺ and [ZnCl₄]^2? to form a 3-D supramolecular network. In 2, π–π stacking interactions between aromatic rings of 1,2,4-triazole and pyridine rings are observed; in 3, hydrogen bonding of Cl ··· H–N and π–π stacking interactions between parallel pyridine rings of L ₃ are observed. The mechanisms of rearrangement reactions of L to L₁ –L₃ are discussed. The fluorescent properties for solid 1 and 3 are also investigated.     

Cobalt(II) coordination polymers built on isomeric dipyridyl triazole ligands with pyromellitic acid: Synthesis, characterization and their effects on the thermal decomposition of ammonium perchlorate

Three new cobalt(Ⅱ) coordination compounds,[Co(3,3’-Hbpt)2(H2pm)(H2O)2]·2H2O(1),[Co(4,4’-Hbpt)(pm)0.5(H2O)]·3H2O (2) and [Co(3,4’-Hbpt)(pm) 0.5 (H2O)3]·2H2O(3)(3,3’-Hbpt=3,5-bis(3-pyridyl)-1H-1,2,4-triazole;4,4’-bpt=3,5-bis(4-pyridyl)1H-1,2,4-triazole,3,4’-Hbpt=3-(3-pyridyl)-5-(4’-pyridyl)-1H-1,2,4-triazole and H4pm=pyromellitic acid) have been synthesized by hydrothermal reactions.Single-crystal X-ray diffraction reveals that compound 1 has a one-dimensional (1D) chain network,2 exhibits a four-connected three-dimensional (3D) structure with 1D open channels encapsulated by water molecules,while 3 displays a regular two-dimensional (2D) architecture connected through 1D metal helical chains.In addition,the efficacy of compounds 1-3 as additives to promote the thermal decomposition of ammonium perchlorate (AP) is explored by differential scanning calorimetry (DSC).     

Über Chalkogenolate. 111. Untersuchungen über Perthiocyansäure. 4. Kristall- und Molekülstruktur von Dimethylperthiocyanat

On Chalcogenolates. 111. Studies on Perthiocyanic Acid. 4. Crystal and Molecular Structure of Dimethyl Perthiocyanate (CH₃)₂C₂N₂S₃ crystallizes with Z = 4 in the monoclinic space group P2₁/c with cell dimensions a = 7.661(4) Å, b = 11.675(5) Å, c = 9.549(5) Å, β = 116.7(3)·. The crystal and molecular structure has been determined from single X-ray data at 20°C and refined to a conventional R of 0.062. The structure consists of isolated 3,5-bis(methylmercapto)-1,2,4-thiadiazole molecules. The 1,2,4-thiadiazole ring is plane and stabilized by mesomerism.     

Synthesis and structural characterization of 2D Zn(II), Cd(II), and Co(II) coordination polymers containing 3-chloro-1,2-benzenedicarboxylate and positional isomers of triazole-bipyridine

Three compounds, [Zn₂L₂(4,4′-bpt)₂] _n (1), [Cd₂L₂(3,4′-bpt)(H₂O)₂] _n (2) and {[CoL(3,3′-bpt)(H₂O)]?H₂O} _n (3) (L?=?3-Cl-1,2-benzenedicarboxylate dianion, 4,4′-bpt?=?1H-3,5-bs(4-pyridyl)-1,2,4-itriazole, 3,4′-bpt?=?1H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole and 3,3′-bpt?=?1H-3,5-bis(3-pyridyl)-1,2,4-triazole), based on three positionally isomeric triazole-bipyridine ligands, were synthesized. Structural analyses of 1–3 reveal diverse 2-D network structures, which are based on different [ML] _n (M?=?Zn, Cd, Co) chains. In the [ZnL] _n chains of 1, the carboxylic groups of L connect the adjacent Zn(II) centers with a monodentate bridging coordination mode (μ₂-η^{1 ?}/^? η¹ ). In 2, [CdL] _n is a double chain connected by the carboxylic groups of L with μ₃-η^{1 ?}/^? η²/η² and μ₃-η^{1 ?}/^? η^{1 ?}/^? η² bridges. The [CoL] _n chains of 3 are formed by the carboxylic groups of L with the μ₂-η^{1 ?}/^? η² coordination mode. The powder X-ray diffraction and the thermal stability of 1–3, the luminescent properties of 1 and 2, and the magnetic behavior of 3 have been briefly investigated.     

Substituent effects in the zinc(II) coordination chemistry of isomeric pyridylpyrazole ligands

Abstract

Pyrazoles with unsymmetric substitution are useful ligands in coordination chemistry, but are under-developed due to synthetic challenges in accessing the pure isomers. We have prepared four new structurally related N-(2-pyridyl)-3,5-dialkylpyrazole ligands, L1–L4, and probed their coordination chemistry in the crystalline phase and in solution to elucidate a relationship between steric influence of the alkyl substituents, the stability of the subsequent metal complexes, and their crystal packing influences. We find that L1 and L2, bearing linear or branched alkyl substituents, show similar stabilities and crystal packing motifs featuring π···π and C-H···Cl interactions in the crystalline complexes 1 and 2, respectively. The cyclohexyl-fused species L3 and L4 vary both in the solution stability of complexes 3 and 4, respectively, and in their crystal packing. Complex [ZnCl₂(L3)] (3) is a mononuclear complex similar to 1 and 2, albeit with π···π interactions disallowed by the bulk of the cyclohexyl ring. Reaction of isomeric L4 with ZnCl₂ gives two polymorphic complexes, 4α and 4β, of the form [Zn₂Cl₂(μ₂-Cl)₂(L4)₂], varying only in their long-range packing modes. These results show the importance of understanding the steric influences in substituted pyridylpyrazoles, which determine both stability in solution and speciation in the crystalline phase.     

Cd(II) and Cu(II) coordination polymers based on a multidentate N-donor ligand: syntheses,crystal structures,optical band gaps,and photoluminescence

Four Cd(II)- and Cu(II)-containing coordination polymers (CPs) based on a multidentate N-donor ligand and varied dicarboxylate anions, [Cd(3,3′-tmbpt)(p-bdc)]·2.5H₂O (1), [Cd(3,3′-tmbpt)(m-bdc)]·2H₂O (2), [Cu(3,3′-tmbpt)(m-bdc)]·H₂O (3), and [Cu(3,3′-tmbpt)(p-bdc)]·2H₂O (4), where 3,3′-tmbpt = 1 ? ((1H-1,2,4-triazol-1-yl)methyl)-3,5-bis(3-pyridyl)-1,2,4-triazole, p-H₂bdc = 1,4-benzenedicarboxylic acid, and m-H₂bdc = 1,3-benzenedicarboxylic acid, have been prepared hydrothermally. The structures of the compounds were determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra and elemental analyses. Compound 1 exhibits a 3-D twofold interpenetrating framework with a 6⁵·8 CdSO₄ topology. Compound 2 is a 2-D layer containing meso-helical chains with a 4⁴·6² sql topology. Compound 3 shows a 1-D → 3-D interdigitated architecture while 4 displays a 2-D → 3-D interdigitated architecture. The structural differences of the compounds indicate that the dicarboxylate anions and the central metal ions play important roles in the resulting structures of CPs. Optical band gaps and solid-state photoluminescent properties have also been studied.     

Docking studies to evaluate the biological activities of the Co(II) and Ni(II) complexes containing the triazine unit: supported by structural,spectral, and theoretical studies

Abstract

Two complexes of 5,6-di(2-furyl)-3-(2-pyridyl)-1,2,4-triazine (L), [Co(L)₂(NO₃)₂] (1), and [Ni(L)₂(NO₃)₂] (2), were prepared and identified along with L by elemental analysis, FT-IR, UV-Vis, and ¹H NMR spectroscopies and single-crystal X-ray diffraction. All coordination modes of the 1,2,4-triazine unit and also of the nitrato ligand in coordination with cobalt and nickel atoms were studied by analysis of the Cambridge Structural Database (CSD) to compare with the new results. X-ray structure analysis of complexes 1 and 2 revealed that the metal atom in both complexes has an octahedral geometry with MN₄O₂ environment (M: Co (1), Ni (2)). The ligand acts as a bidentate N^tzN^py-donor and forms a five-membered planar chelate ring. In addition to the hydrogen bonds, the crystal network is stabilized by π–π stacking interactions between pyridine rings of the ligands of adjacent complexes. The thermodynamic stability of the two conformational isomers of the 5,6-di(2-furyl)-3-(2-pyridyl)-1,2,4-triazine and their charge distribution patterns were studied by DFT and NBO analysis, respectively. The ability of the uncoordinated ligand conformers and complexes 1 and 2 to interact with nine selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, and Top II) was investigated by docking calculations and compared with that of doxorubicin. Also an analog of the ligand in which the furyl rings are replaced by phenyl groups is included in these studies.     

Effect of bis-triazole based secondary ligands on the structure of coordination polymers generated from terephthalic acid

Reactions of Zn/Cd(ClO₄)₂·6H₂O and terephthalic acid (H₂BDC) with three bis-triazole ligands afforded three coordination polymers under solvothermal conditions, {[Zn(BDC)(L1)]·H₂BDC}_n (1), {[Zn(BDC)(L2)_0.5]·H₂O}_n (2), and {[Cd₂(BDC)₂(L3)(DMF)(H₂O)₂]·2H₂O]}_n (3) (L1 = bis(4-(4H-1,2,4-triazol-4-yl)phenyl)methane, L2 = bis(4-(4H-1,2,4-triazol-4-yl)phenyl)ethane, and L3 = 1,4-bis(4H-1,2,4-triazol-4-yl)benzene). Solid 1 displayed a 2-D structure which contained two kinds of rings. Both 2 and 3 were 3-D threefold interpenetrating frameworks. Solid 2 showed a α–Po-related net, while 3 exhibited an acs-related network with a binuclear node. Furthermore, the photoluminescent properties of 1–3 were investigated.     

Zinc(II) and cadmium(II) complexes with PDT: study of the effect of weak interactions on crystal packing

Two new zinc(II) and cadmium(II) complexes, [Zn(PDT)₂(NCS)₂] (1) and [Cd((PDT)₂I_1.6(H₂O)_0.4(OH)_0.4] · 0.4H₂O (2) (“PDT” is the abbreviation of 3-(2-pyridyl)-5, 6-diphenyl-1,2,4-triazine), have been synthesized and characterized by elemental analysis, IR, ¹H NMR spectroscopy, and studied by X-ray crystallography. Zinc(II) in 1 is six coordinate ZnN₆. 2 is a co-crystal with cadmium(II) being 60% six-coordinated with a CdN₄I₂ environment and 40% seven-coordinated with a CdN₄O₂I environment. The supramolecular features in these complexes are guided/controlled by weak directional intermolecular S ··· π, C–H ··· π, C–H ··· I, and π ··· π interactions.     

A Cu(II) coordination framework constructed by the inorganic layer and a bent dipyridyl ligand: Synthesis,structure and magnetic properties

A new Cu(II) coordination framework {[Cu(4-abpt)(μ₃-SO₄^2-)(H₂O)]·3H₂O}_∞ (1) based on the Cu–SO₄^2- inorganic layer and the bent dipyridyl ligand was obtained under solvothermal conditions (4-abpt ​= ​4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole). The compound displays a three-dimensional (3D) “pillar-layer” framework, which can be simplified into a 3,5-connected gra topology. Furthermore, the magnetic properties of 1 have been investigated. As a result, compound 1 displays a weak antiferromagnetic interaction among the Cu(II) centers.     

Supramolecular architectures with ladder and lamellar topologies using metal-ligand coordination units via C–H···Cl and O–H···Cl hydrogen bonding

New Mn^II/Cu^II/Zn^II complexes [(L¹)MnCl₂] (1), [(L²)CuCl₂]·0.5H₂O (2) and [(L²)ZnCl(H₂O)][ClO₄] (3), containing (2-pyridyl)alkylamine ligands, N-methyl-N,N-bis(2-pyridylmethyl)amine (L¹) and methyl[2-(2-pyridyl)ethyl](2-pyridylmethyl)amine (L²), have been prepared and characterized, including X-ray crystallography. The most striking feature of the structures of these complexes is the formation of molecular ladder and lamellar topology through the crystal packing arrangement, determined by both strong O–H···Cl and weak (however, multiple) C–H···Cl hydrogen-bonding interactions, to maintain the neutral/cationic metal-ligand coordination units linked to each other. In 3, additional secondary interactions are observed involving coordinated solvent and the counter-ion. The results presented here demonstrate that (i) the choice of organic ligands to provide flexibility and inherent potential to participate in hydrogen-bonding interactions, (ii) the coordination geometry preferences of metal ions, (iii) the number of metal-bound chloride ion and (iv) the presence of solvent/counter-anion have a great influence on supramolecular network topology.     

Syntheses and structures of Cd(II) and Co(II) compounds of 4-[(3-pyridyl)methylamino]benzoate anion

Three coordination polymers containing Cd(II) and Co(II), connected via 4-[(3-pyridyl)methylamino]benzoate (L^?), have been synthesized in hydrothermal conditions. In [Cd(L)Cl] _n (1), adjacent Cd(II) cations are linked by carboxylates to give a dinuclear cluster. Pairs of L^? bridge the dinuclear cluster to form double helical chains, and these chains are further linked by Cl^? to produce a 4-connected net with (4²?·?6³?·?8) topology. [CdL₂] _n (2) contains 1-D ladder-like chains. The packing structure displays a 3-D supramolecular structure, with π?···?π interactions stabilizing the framework. [CoL₂] _n (3) has a 2-D extended supramolecular structure via π?···?π interactions of 1-D coordination polymers of 3. The crystal structures of 1–3 have been determined by single-crystal X-ray diffraction. Luminescent properties for 1 and 2 are discussed.     

Synthesis,characterization, crystal structure,and DNA binding of two copper(II)–hydrazone complexes

Two new Cu(II)–hydrazone complexes, [Cu(L)(Hbpe)ClO₄]·ClO₄·[Cu(L)Cl] (1) and [Cu(HL)₂]·1.5ClO₄·0.5OH (2) (where HL?=?(E)-N′-(1-(pyridine-2-yl)ethylidene)benzohydrazide and bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene), have been synthesized and characterized by physicochemical methods. The structures of the complexes have been established by single-crystal X-ray diffraction direct methods, which reveal that the metal ions have distorted square-pyramidal and square-planar geometries in 1, and a distorted octahedral geometry in 2. DNA binding of HL, 1, and 2, performed by UV–vis titration in tris-buffer medium, yielded binding constants, which are 9.5 × 10³, 1.88 × 10⁴, and 4.66 × 10⁴ M^?1, respectively. Viscosity measurements suggest a surface or groove-binding mode of interaction between CT-DNA with HL, 1, and 2.     

Synthesis,structure, and photoluminescence of a (4,6)-connected Cu(I)–CN–triazolate framework built with a unique heptanuclear hybrid cluster

A 3-D Cu(I)–CN–triazolate hybrid coordination polymer, {Cu₉(NH₂-BPT)₂(BPT)₂(CN)₇}_n (1) (NH₂-BPT = 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole, BPT = 3,5-bis(3-pyridyl)-1,2,4-triazole), has been synthesized via self-assembly of NH₂-BPT, CuCN, and K₃Fe(CN)₆ under hydrothermal conditions. Single-crystal X-ray diffraction data show that four of the five independent copper centers in 1 have a three-coordinated trigonal coordination geometry, and the remaining copper center has a two-coordinated linear geometry. Three Cu ions are linked by one cisoid-BPT and two CN^? to form a 16-membered ring subunit, which is joined by the two-coordinate copper center via the triazole N(4)-position to generate an unprecedented [Cu₇(BPT)₂(CN)₄] hybrid heptanuclear cluster. Each heptanuclear motif is linked to two adjacent [Cu₇] clusters through four CN^? anions, and further to four [Cu–CN–Cu] binuclear clusters through two transoid-NH₂-BPT ligands. Each of these [Cu–CN–Cu] units is linked to four neighboring heptanuclear motifs. The overall geometry is a 3-D (4,6)-connected topological framework with Schläfli symbol of (4^4?×?6²)(4^4?×?6^10?×?8). Compound 1 also exhibits high thermal stability and strong green fluorescence emission at 536?nm in the solid state.     

Anion-induced assembly of two distinct copper(II) coordination polymers with a versatile multidentate N-donor ligand

Reaction of a ligand N-(3,5-di-2-pyrazinyl-4H-1,2,4-triazol-4-yl)-2-pyrazinecarboxamide (Hpztp) with CuSO₄ and Cu(acac)₂ (acac = acetylacetonate), respectively, yields two distinct Cu^II coordination polymers {[Cu₃(pztp)₂(SO₄)₂(H₂O)₂]·3H₂O} _n and {[Cu(pztp)(acac)]·0.5H₂O} _n . Both complexes have been structurally determined and also characterized by physicochemical and spectroscopic methods. The results reveal that by using different anions (SO₄ ^2? versus acac^?), the dimensionality (from 2D to 1D) of the resulting coordination architectures as well as conformations and binding fashions of the pztp ligand are significantly changed. That is to say, the selection of anions will play a key role in inducing the formation of the crystalline materials. The thermal stabilities of both complexes have also been explored and discussed.     

Thermal and photoinduced valence tautomerism of a chain compound

Herein reported is an example of one-dimensional coordination polymer [CoII(3,5-DBsq)2(dpg)]·(3,5-H2DBcat)2 (1) (3,5-DBsq = 3,5-di-tert-butylsemiquinonate, 3,5-H2DBcat = 3,5-di-tert-butyl-benzene-1,2-diol, dpg = meso-alpha,beta-di(4-pyridyl)glycol) capable of undergoing thermal and photoinduced valence tautomeric transitions.     

Crystal structures of complexes of 3,5,6-tris(2-pyridyl)-1,2,4-triazine: [Pb(TPT)(NO3)2] n and [Pb(TPT)2(ClO4)(H2O)] · ClO4 · H2O

Two new Pb(II) complexes, [Pb(TPT)(NO₃)₂] _n (1) and [Pb(TPT)₂(ClO₄)(H₂O)] · ClO₄ · H₂O (2) (TPT is the abbreviation of 3,5,6-tris(2-pyridyl)-1,2,4-triazine), have been synthesized and characterized by single-crystal X-ray diffraction. Lead(II) in the compounds of 1 and 2 is nine coordinate (rare mode), PbN₃O₆ and PbN₆O₃, respectively. Both have hemidirected coordination geometries. The supramolecular features in these complexes are guided/controlled by hydrogen bonding and weak directional intermolecular C–H ··· O and π ··· π interactions. The thermal stabilities of 1 and 2 were investigated by thermogravimetric measurements.