Zinc complexes with 3-Pyridinyl-5-(2-salicylideneiminophenyl)-1H-1,2,4-triazoles

New coordination compounds of zinc with 3-(pyridine-2-yl)-5-(2-salicylideneiminophenyl)-1H-1,2,4-triazole (H₂L¹) and 3-(pyridine-4-yl)-5-(2-salicylideneiminophenyl)-1H-1,2,4-triazole (H₂L²) are obtained. According to X-ray diffraction data, binuclear zinc complexes with L¹, namely, [Zn₂L₂¹]. 0.5EtOH and [Zn₂L₂¹] · 2C₄H₈O₂ · 2H₂O obtained in different solvents, are structurally related molecular complexes. The product of the reaction with H₂L² is the {[ZnL²(Py)] · CHCl₃} _n coordination polymer. The 1,2,4-triazoles under study and the complexes on their basis luminesce in solutions with emission maxima ranging from 412 to 503 nm. These coordination compounds in the solid state emit in the green range of the spectrum (λ_max = 496 and 485 nm).     

Crystal structure and thermal properties of novel Co(II) complexes with 2,6-pyridine-dicarboxylate containing infinite one-dimensional chain: [CoL1(H2O)4][Co(pydc)2]·2H2O and [Co(H2O)6]×[Co(pydc)2]L2·H2O (L1 = 1,3-bis(4-pyridyl)propane, L2 = 3-amino-1H-1,2,4-triazole, pydc = 2,6-pyridine-dicarboxylic acid)

The two title compounds were prepared from the ligand pydc with cobalt(II) acetate in the presence of L¹ and L² (L¹ = 1,3-bis(4-pyridyl)propane, L² = 3-amino-1H-1,2,4-triazole, pydc = 2,6-pyridinedicarboxylic acid). The complexes were characterized by elemental analysis, IR spectrum and single crystal X-ray diffraction. Single crystal analysis shows that in two complexes coordination number around Co atom is six with distorted octahedral geometry, and both two complexes consist of ion pairs containing cationic [Co(H₂O) _n ]²⁺ and anionic [Co(pydc)₂]^2- units.     

Ni(II) and Cu(II) complexes of new unsymmetrical N2O2 Schiff bases derived from 3-(2-aminobenzylimino)-1-phenylbutan-1-ol: synthesis,structure, antibacterial properties,and electrochemistry

Two new N₂O₂ unsymmetrical Schiff bases, H₂L¹ = 3-[({o-[(E)-(o-hydroxyphenyl)methylideneamino]phenyl}methyl)imino]-1-phenyl-1-buten-1-ol and H₂L² = 3-[({o-[(E)-(2-hydroxy-1-naphthyl)methylideneamino]phenyl}methyl)imino]-1-phenyl-1-buten-1-ol, and their copper(II) and nickel(II) complexes, [CuL¹] (1), [CuL²] (2), [NiL¹] (3), and [NiL²] (4), have been synthesized and characterized by elemental analyses and spectroscopic methods. The crystal structures of these complexes have been determined by X-ray diffraction. The coordination geometry around Cu(II) and Ni(II) centers is described as distorted square planar in all complexes with the CuN₂O₂ coordination more distorted than the Ni ones. The electrochemical studies of these complexes indicate a good correlation between the structural distortion and the redox potentials of the metal centers. The ligand and metal complexes were also screened for their in vitro antibacterial activity.     

Synthesis,crystal structure,Hirshfeld surfaces,and spectral properties of Cu(II) and Co(II) complexes with 3-phenoxymethyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole

A new asymmetrical substituted triazole, 3-phenoxymethyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole (L) and its complexes, cis-[Cu₂ L ₂Cl₄]·2CH₃CN (1) and trans-[CoL ₂Cl₂]·2H₂O·2CH₃CN (2), have been synthesized and characterized by IR, single-crystal X-ray diffraction, thermogravimetric analyses and Hirshfeld surfaces. In the structure, two L are mainly stabilized by an intermolecular C–H?N hydrogen bond. In 1 (or 2), each L involves a doubly-bidentate (or chelating bidentate) coordination mode through one pyridine and two nitrogens (or one) of triazole, respectively. Complex 1 has a distorted trigonal bipyramidal [CuN₃Cl₂] core with two cis Cl^? while 2 shows a distorted octahedron [CoN₄Cl₂] with two trans Cl^?. We also prepared molecular Hirshfeld surface and fingerprint plot for L, 1 and 2, which revealed the influence of different metals on coordinate of L.     

Three copper(II) complexes constructed from 4-(2-pyridyl)-<Emphasis Type="Italic">1H</Emphasis>-1,2,3-triazole ligands: syntheses,structures, optical,and electrochemical properties

Three Cu(II) complexes constructed from 4-(2-pyridyl)-1H-1,2,3-triazole (L), namely, [CuL₂Cl₂]·H₂O, [CuL₂(CH₃OH)(NO₃)]NO₃ and [CuL₂(H₂O)]SO₄, have been synthesized and characterized. X-ray crystal structure analyses revealed that [CuL₂Cl₂]·H₂O and [CuL₂(CH₃OH)(NO₃)]NO₃ have octahedral geometries, whilst [CuL₂(H₂O)]SO₄ adopts a square-pyramidal coordination geometry. In all three complexes, the Cu(II) atoms are chelated by two L ligands in the basal plane, whilst the apical positions are occupied by Cl^?, NO₃^?, CH₃OH or H₂O. The bandgaps between the HOMO and LUMO were estimated by cyclic voltammetry (CV) and diffuse reflectance spectroscopy (DRS) to be 3.43, 3.12, and 3.74 eV, respectively. Theoretical calculations on each structure gave similar results to the experiments. Frontier molecular orbital analyses showed that the higher electron density on the apical ligand, the lower the bandgap.     

Cu(II) and Co(II) complexes with 3,5-diphenyl-4-amino-1,2,4-triazole: Synthesis and study

The Cu(II) and Co(II) complexes with 3,5-diphenyl-4-amino-1,2,4-triazole (L) of the composition CuLA₂ · H₂O (A = Cl^?, Br^?), CuL₂A₂ (A = Cl^?, Br^?, NO ₃ ^? ), CoL₂A₂ · nH₂O (A = Cl^?, n = 1; A = NCS^?, n = 0) are synthesized. In these complexes, the ligand L is coordinated to a metal in monodentate mode through the heterocyclic N(1) atom. The Cu: L = 1: 1 complexes have binuclear structures with the anions acting as bridges, whereas the M: L = 1: 2 complexes are mononuclear. Both ferro-and antiferromagnetic exchange interactions are detected for the synthesized complexes.     

Synthesis,structural characterization,antimicrobial, DNA-binding,and photo-induced DNA cleavage activity of some bio-sensitive Schiff base copper(II) complexes

Schiff base mixed-ligand copper complexes [CuL¹(phen)Cl₂], [CuL¹(bipy)Cl₂], [Cu(L¹)₂Cl₂], [Cu(L²)₂Cl₂], [CuL²(bipy)Cl₂], and [CuL²(phen)Cl₂] (where L^1?=?4-[3,4-dimethoxy-benzylidene]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazole-3-one; L^2?=?4-[3-hydroxy-4-nitro-benzylidene]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazole-3-one; phen?=?1,10-phenanthroline; and bipy?=?2,2′-bipyridine) have been synthesized and characterized. Their DNA-binding properties have been studied by electronic absorption spectra, viscosity, and electrochemical measurements. The absorption spectral and viscosity results suggest that the copper(II) complexes bind to DNA via partial intercalation. The addition of DNA resulting in the decrease of the peak current of the copper(II) complexes indicates their interaction. Interaction between the complexes and DNA has also been investigated by submarine gel electrophoresis. The copper complexes cleave supercoiled pUC19 DNA to nicked and linear forms through hydroxyl radical and singlet oxygen in the presence of 3-mercaptopropionic acid as the reducing agent. These copper complexes promote the photocleavage of pUC19 DNA under irradiation at 360?nm. Mechanistic study reveals that singlet oxygen is likely to be the reactive species responsible for the cleavage of plasmid DNA by the synthesized complexes. The in vitro antimicrobial study indicates that the metal chelates have higher activity against the bacterial and fungal strains than the free ligands.     

Two novel four-coordinated zinc(II) complexes [Zn(dmatrz)<Subscript>2</Subscript>Cl<Subscript>2</Subscript>] and [Zn(dmatrz)<Subscript>2</Subscript>(SCN)<Subscript>2</Subscript>] exhibiting strong blue fluorescent properties

Two novel complexes, [Zn(dmatrz)₂]Cl₂ (1) and [Zn(dmatrz)₂(SCN)₂] (2), have been prepared and characterized by X-ray crystallography, absorption and luminescence spectrometries (dmatrz=3,5-dimethy-4-amino-1,2,4-triazole). The coordination environment of the zinc(II) ions in (1) and (2) has a distorted tetrahedral geometry completed via two independent nitrogen atoms of two triazole ligands and two anions, respectively. Both (1) and (2) show strong blue luminescence properties. Furthermore, (1) displays stronger blue photoluminescence than (2) as the result of different anions (Cl^- and SCN^-) coordinated to the zinc(II) ions.     

Complexes of Co(II), Ni(II), and Cu(II) with 4-(3,4-dichlorophenyl)-1,2,4-triazole

Novel oligonuclear complexes of Co(II), Ni(II), and Cu(II) with 4-(3,4-dichlorophenyl)-1,2,4-triazole (L) of the composition [M₃L₁₀(H₂O)₂](NO₃)₆ (M = Co(II), Ni(II)), [Ni₃L₆(H₂O)₆]Hal₆ (Hal = Cl^?, Br^?), and [Cu₅L₁₆(H₂O)₂](NO₃)₁₀ · 2H₂O were synthesized and studied by magnetic susceptibility, electronic and IR spectroscopy, and powder X-ray diffraction methods. All the above complexes are X-ray amorphous. Antifer-romagnetic exchange interactions between the M²⁺ ions were discovered in the [Co₃L₁₀(H₂O)₂](NO₃)₆ and [Ni₃L₁₀(H₂O)₂](NO₃)₆ complexes, whereas ferromagnetic exchange interactions were observed in the complexes [Ni₃L₆(H₂O)₆]Cl₆, [Ni₃L₆(H₂O)₆]Br₆, and [Cu₅L₁₆(H₂O)₂](NO₃)₁₀ · 2H₂O.     

Synthesis and study of the structure of new 3d-metal coordination compounds with substituted 2-amino-4(5H)-ketothiophens

A series of new 3d-metal complexes based on 2-amino-3-(1-methylbenzimidazol-2-yl)-4(5H)-ketothiophen (HL¹) and 2-amino-3-(2-benzothiazolyl)-4(5H)-ketothiophen (HL²) were synthesized. Compounds of the general formulas [ML₂] and [M(HL¹)₂Cl₂] (where M = Co²⁺, Ni²⁺, Zn²⁺, Cu²⁺) were prepared by the reaction of the above mentioned ligands with the corresponding acetate (for [ML₂]) or chloride (for [M(HL¹)₂Cl₂]) salts in a methanol or a methanol–chloroform medium. The choice of the anion in the initial metal salt, as well as the selection of the ligand, is crucial for obtaining coordination compounds with a neutral or deprotonated form of the 2-amino-4(5H)-ketothiophens. Thus, in contrast to HL¹, complexes with the neutral form of HL² cannot be obtained under the same conditions. All the complexes were studied by spectroscopic methods and X-ray crystallography (for [CuL¹₂] · H₂O). The coordination polyhedron of the copper atom is formed by four nitrogen atoms from two ligand anions and the geometry of the coordination sphere is intermediate between tetrahedral and square-planar.     

Coordination compounds of copper with 2-formylpyridine 4-(dimethylphenyl)thiosemicarbazones

2-Formylpyridine 4-(2,6-dimethylphenyl)-(HL¹), 4-(2,5-dimethylphenyl)-(HL²), 4-(3,4-dimethylphenyl)-(HL³), and 4-(2,4-dimethylphenyl)thiosemicarbazones (HL⁴) react with copper chloride and nitrate to form coordination compounds CuL^1–4X·nH₂O [X = Cl^?, NO ₃ ^? ; n = 1, 2]. All compounds have a polynuclear structure. Azomethines HL^1–4 act as the bridging monodeprotonated tridentate N,N,S-ligands. The thermolysis of the complexes includes the dehydration (70–90°C) and total thermal decomposition (350–520°C). The complexes synthesized exhibit a selective antimicrobial activity against a series of standard strains of Staphylococcus aureus and Escherichia coli in the concentration range of 0.009–37.5 μg ml^?1.     

Syntheses and crystal structures of two novel Cu(II) and Co(II) complexes with 3-methyl-4-(p-bromophenyl)-5-(2-pyridyl)-1,2,4-triazole

A new ligand, 3-methyl-4-(p-bromophenyl)-5-(2-pyridyl)-1,2,4-triazole (L) and its complexes, trans-[CuL₂(ClO₄)₂] (1) and cis-[CoL₂(H₂O)₂](ClO₄)₂·H₂O·CH₃OH (2), have been synthesized and characterized by UV, IR, electrospray ionization mass spectrum, elemental analyses, and single-crystal X-ray diffraction methods. In the structure, two L ligands are stabilized by intermolecular π···π interactions between the triazole rings. In the complexes, each L ligand adopts a chelating bidentate mode through N atom of pyridyl group and one N atom of the triazole. Both complexes have a similar distorted octahedral [MN₄O₂] core (M = Cu²⁺ and Co²⁺) with two ClO₄ ⁻ ions in the trans position in 1 but two H₂O molecules in the cis arrangement in 2.     

Synthesis,DNA-binding and cleavage studies of macrocyclic copper(II) complexes

Two macrocyclic copper(II) complexes, [CuL¹](ClO₄)₂ (L¹ = 2,6,9,13-tetraparacyclophane, a Schiff base) and [CuL²]Cl₂ [L² = 3,10-bis(2-benzyl)-1,3,5,8,10,13-hexaazacyclotetradecane] have been prepared and characterized by elemental analysis, u.v.–vis., i.r. and mass spectra. Absorption, fluorescence, circular dichroic spectra and viscosity experiments have been carried out on the interaction of the two complexes with calf thymus CT DNA. The results suggest that both complexes can bind to CT DNA by intercalation via the aromatic moiety ring in the macrocycle into the base pairs of DNA. [CuL¹](ClO₄)₂ binds to CT DNA more strongly than [CuL²]Cl₂. The position of the aromatic ring in the macrocycle plays an important role in deciding the extent of binding of the complexes to DNA. Significantly, the complexes have been found to be single-strand DNA cleavers in the presence of H₂O₂ or/and 2-mercaptoethanol.     

Synthesis and characterization of the [Cu(Cin2bda)2]ClO4 and [Cu(Ncin2bda)2]ClO4 complexes: Crystal structure of [Cu(Ncin2bda)2]ClO4

Two copper(I) complexes [Cu(Cin₂bda)₂]ClO₄ (I) and [Cu(Ncin₂bda)₂]ClO₄ (II) have been prepared by the reaction of the ligands N²,N²′-bis(3-phenylallylidene)biphenyl-2,2′-diamine (L¹) and N²,N²′-bis[3-(2-nitrophenyl)allylidene]biphenyl-2,2′-diamine (L²) and copper(I) salt. These compounds were characterized by CHN analyses, ¹H NMR, IR, and UV-Vis spectroscopy. The C=N stretching frequency in the copper(I) complexes shows a shift to a lower frequency relative to the free ligand due to the coordination of the nitrogen atoms. The crystal and molecular structure of II was determined by X-ray single-crystal crystallography. The coordination polyhedron about the copper(I) center in the complex is best described as a distorted tetrahedron. A quasireversible redox behavior was observed for complexes I and II. The article is published in the original.     

N-COORDINATED COPPER(II) COMPLEXES WITH 2-S-METHYL-5,5-DIMETHYLIMIDAZOLIN-4-ONE (L). CRYSTAL STRUCTURE OF [CuL4H2O][CuCl4]

Abstract

The reaction between CuX₂ (X = Cl, Br, NO₃, ClO₄) and 2-S-methyl-5,5-dimethylimidazolin-4-one (L) yields complexes having stoichiometry CuL₂Cl₂ · 1/2H₂O (1), CuL₂Br₂ (2), CuL₄X₂ · 2H₂O [X = NO₃ (3), ClO₄ (4)]. The X-ray crystal structure solved for 1 showed that it contains discrete [CuL₄ · H₂O]²⁺ and [CuCl₄]^2- ions, separated by normal van der Waals contacts. The [CuL₄H₂O]²⁺ cation has crystallographic C ₄ symmetry, with the copper atom and the oxygen of the water molecule lying on a four-fold axis of the space group P4/n and the metal atom in a square-pyramidal coordination geometry, obtained by a square basal plane defined by four N atoms and the apex occupied by the water molecule. The [CuCl₄]^2- anion shows a very flattened tetrahedral geometry. FT-IR and FT-Raman spectra of 1–4 show that 2,3 and 4 also are N(3)-coordinated to copper; nitrate and perchlorate do not coordinate. The v(CuO) vibrations are present at about 380 cm^?1 for 3 and 4, while for 2 v(CuBr) are at 224 and 215 cm^?1. Esr data for 1–4 recorded on solid samples highlight a d_x ² - y² ground state for the cation of 1, 3, and 4 which is typical for tetragonally elongated monomeric copper(II) complexes. Compound 2 exhibits two couples of g values characteristic of two independent copper centres both with compressed tetrahedral geometry. The deconvoluted reflectance spectra of 1–4 substantially confirm the presence of CuN₄ and CuBr₄ chromophores in 2 and a trans-CuN₄O₂ chromophore in 3 and 4. For the latter complexes an orbital sequence d_{x² - y²} > d_xy > d_z² > d_xy, d_yz is also suggested on the basis of the similarity between L and imidazole type ligands.     

Fe(II) complex with chiral pyrazolylquinoline L and Fe(II), Co(II), and Cu(II) complexes with achiral pyrazolylquinoline L1: Synthesis and properties. The crystal structures of [ML1Cl2] (M = Fe, Co, and Cu)

The complexes FeLCl₂ (I), [FeL¹Cl₂] (II), [CoL¹Cl₂] (III), and [CuL¹Cl₂] (IV) (where L and L¹ are chiral and achiral pyrazolylquinolines, respectively) were obtained. Complexes II–IV were structurally characterized by single-crystal X-ray diffraction analysis. Crystals of complexes II and III are triclinic (space group P $ \bar 1 The complexes FeLCl₂ (I), [FeL¹Cl₂] (II), [CoL¹Cl₂] (III), and [CuL¹Cl₂] (IV) (where L and L¹ are chiral and achiral pyrazolylquinolines, respectively) were obtained. Complexes II–IV were structurally characterized by single-crystal X-ray diffraction analysis. Crystals of complexes II and III are triclinic (space group P ) and crystals of complex IV are monoclinic (space group P2₁/n). Structures II–IV are built from discrete mononuclear acentric molecules. In these complexes, the M²⁺ ion (M = Fe, Co, and Cu) coordinates two N atoms of the bidentate chelating ligand L¹ and two Cl atoms. The coordination cores MCl₂N₂ are distorted tetrahedra. For complexes I and II, μ_eff = 5.05 and 5.07 μ_B, respectively, correspond to the high-spin configuration d ⁶. For complex III, μ_eff = 4.51 μ_B (high-spin configuration d ⁷) and for complex IV, μ_eff = 1.80 μ_B (configuration d ⁹). Original Russian Text ? Z.A. Savel’eva, L.A. Glinskaya, R.F. Klevtsova, S.A. Popov, A.V. Tkachev, N.V. Semikolenova, V.A. Zakharov, S.V. Larionov, 2008, published in Koordinatsionnaya Khimiya, 2008, Vol. 34, No. 4, pp. 285–292.     

Synthesis and Structure of Metal Complexes of 1-(1-R-3-Methylpyrazole-5-onilidene-4)-1,2,3,4-tetrahydroisoquinoline Derivatives

Twenty new complexes were synthesized by reacting Co(II), Cu(II), Zn, Cr(III), Fe(III), Cd and Ag salts with 3,3-dimethyl-1-(3-methylpyrazole-5-onilidene-4)-1,2,3,4-tetrahydroisoquinoline (L¹), spiro{cyclohexane-1,3"-[1-(1-phenyl-3-methylpyrazole-5-onilidene-4)-1,2,3,4-tetrahydroisoquinoline]} (L²), and 3,3-dimethyl-1-(1-phenyl-3-methylpyrazole-5-onilidene-4)-1,2,3,4-tetrahydroisoquinoline (L³). These compounds were studied by IR and electronic absorption spectroscopy. The type of coordination of their ligands was discussed on the basis of the results obtained and X-ray diffraction data for L³ and [CuL₂ ² Cl₂] · 2L² obtained previously.     

Unusual coordination of a chloride ion to six copper ions: Synthesis and crystal structure of copper(II) complexes with 4-(4-hydroxyphenyl)-1,2,4-triazole

Novel copper(II) complexes, molecular [Cu₆(μ₆-Cl)(μ₃-OH)₂(μ-L)₆Cl₉(H₂O)₃] · 3H₂O (1) and polymeric [Cu(μ-L)(μ-OH)(H₂O)₂]Cl (2) (L = 4-(4-hydroxyphenyl)-1,2,4-triazole), have been prepared and characterized by X-ray structural analysis. Compound 1 appears to be an unusual example of a chloride ion with six equal Cu–Cl distances of 2.8397(3) Å. It has also been characterized by X-ray powder diffraction and magnetic measurements. Both complexes have distorted octahedral configurations of copper ions; the coordination cores are CuN₂Cl₂O₂ or CuN₂Cl₃O (1) and CuN₂O₄ (2).     

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.     

Synthesis and study of cobalt(II), nickel(II), and copper(II) complexes with 4-(4-hydroxyphenyl)-1,2,4-triazole

New complexes of Co(II), Ni(II), and Cu(II) nitrates, chlorides, and perchlorates with 4-(4-hydroxyphenyl)-1,2,4-triazole (L) were obtained and examined by single-crystal X-ray diffraction, X-ray powder diffraction, and electronic absorption and IR spectroscopy. The cations of all the complexes have linear trinuclear structures. Ligand L is coordinated to the metal ions in a bidentate bridging fashion through the N(1) and N(2) atoms of the heterocycle. The coordination polyhedron of the metal atoms is a distorted octahedron. The molecular and crystal structures of the complexes [Co₃L₆(H₂O)₆](ClO₄)₆ · 3C₂H₅OH · 3.75H₂O and [M₃L₆(H₂O)₆](ClO₄)₆ · 6H₂O (M = Cu²⁺ and Ni²⁺) were determined.