Synthesis, crystal structures, and urease inhibitory activities of two azido-bridged polynuclear copper(II) complexes with Schiff bases

Two azido-bridged polynuclear Cu(II) complexes with the formulae [Cu(L1)(μ_1,3-N₃)] _n and [Cu(L2)(μ_1,3-N₃)] _n (HL1 = 2-[(2-morpholin-4-ylethylimino)methyl]phenol, HL2 = 2-methoxy-6-[(2-piperidin-1-ylethylimino)methyl]phenol), have been synthesized and characterized by physico-chemical and spectroscopic methods. The Cu atom in each of the complexes is five-coordinate in a square pyramidal geometry, with one O and two N atoms of a Schiff base ligand and one terminal N atom of a bridging azido ligand defining the base-plane, and with another terminal N atom of a symmetry-related azido ligand occupying the apical position. The molecules are linked through end-to-end azido bridges, forming one-dimensional polymeric chains. Both of the complexes show moderate inhibitory activities against jack bean urease.     

Synthesis and crystal structures of Manganese(IV) complexes with tridentate schiff bases

The complexes with the formulae [Mn(L¹)₂] · 0.5H₂O (I) and [Mn(L²)₂] (II), where L¹ and L² are the dianionic form of 2,4-dichloro-6-[(2-hydroxyethylimino)methyl]phenol and 2-{[1-(3-ethoxy-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol, respectively, were obtained and characterized by elemental analysis and IR spectroscopy. The crystal structures of complexes I and II were determined using X-ray diffraction. The crystal of I is orthorhombic space group Fdd2: a = 24.170(2), b = 32.021(3), c = 11.352(2) Å, V = 8785.9(19) ų, Z = 8. The crystal of II is monoclinic space group C2/c: a = 13.931(4), b = 18.381(5), c = 12.444(5) Å, β = 121.980(3)°, V = 2702.9(15) ų, Z = 4. The Mn atom in each of the complexes is in an octahedral coordination.     

Syntheses and crystal structures of two tetranuclear copper(II) complexes with Schiff bases

Two similar tetranuclear copper(II) complexes with the formulae [Cu₄(L1)₂(μ_1,1-N₃)₄(μ₂-CH₃COO)₂] and [Cu₄(L2)₂(μ_1,1-N₃)₂(μ-Br)₂Br₂(CH₃OH)₂], where L1 and L2 are the deprotonated forms of 2-[(2-ethylaminoethylimino)methyl]-5-methoxyphenol and 5-methoxy-2-[(2-piperidin-1-ylethylimino)methyl]phenol, respectively, have been synthesized and characterized by spectroscopic methods and single-crystal X-ray diffraction. Both complexes are centrosymmetric tetranuclear copper(II) compounds. The bridging groups in [Cu₄(L1)₂(μ_1,1-N₃)₄(μ₂-CH₃COO)₂] are μ_1,1-azide ligands and μ₂-acetate ligands, and those in [Cu₄(L2)₂(μ_1,1-N₃)₂(μ-Br)₂Br₂(CH₃OH)₂] are μ_1,1-azide ligands and μ-bromide ligands. Each Cu atom in the complexes is in a square pyramidal geometry.     

Synthesis, crystal structures, and urease inhibitory activity of cooper(II) complexes with schiff bases

A new end-to-end thiocyanato-bridged polynuclear copper(II) complex, [Cu(CP)(μ_1,3-NCS)] _n · nMeOH (I), and a new mononuclear copper(II) complex, [Cu(MP)(ONO₂)(OH₂)] (II) (CP = 4-chloro-2-[(pyridin-2-ylmethylimino)methyl]phenolate, MP = 5-methoxy-2-[(pyridin-2-ylmethylimino)methyl]phenolate), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. The crystal of I is orthorhombic: space group Pbca, a = 10.6161(16) Å, b = 16.340(3) Å, c = 18.840(3) Å, V = 3268.0(9) ų, Z = 8. The crystal of II is triclinic: space group P $ \bar 1 $ , a = 7.5645(2), b = 8.9811(2), c = 11.9412(3) Å, α = 74.4610(10)°, β = 80.5040(10)°, γ = 71.0940(10)°, V = 736.71(3) ų, Z = 2. The Cu atoms in the complexes are in square-pyramidal coordination. The biological test shows that both complexes have strong urease inhibitory activity.     

Synthesis,crystal structures and xanthine oxidase inhibitory activities of two copper(II) complexes with Schiff bases

Two azido-coordinated Schiff base Cu(II) complexes with the formulae [Cu(L1)(N₃)]·MeOH and [Cu(L2)(μ_1,1-N₃)] _n , where L1 is the deprotonated form of 2-chloro-2-[(2-ethylaminoethylimino)methyl]phenol, and L2 is the deprotonated form of 2,4-dibromo-6-[(2-dimethylaminoethylimino)methyl]phenol, have been synthesized and characterized by physico-chemical and spectroscopic methods. The X-ray crystal structures of both complexes have been determined. The Cu atom in [Cu(L1)(N₃)]·MeOH is four-coordinate in a square planar geometry, while [Cu(L2)(μ_1,1-N₃)] _n is five-coordinate with a square pyramidal geometry. The molecules in [Cu(L1)(N₃)]·MeOH are linked by intermolecular O–H···O and N–H···O hydrogen bonds, forming dimers. The molecules in [Cu(L2)(μ_1,1-N₃)] _n are linked through end-on azido bridges, forming one-dimensional chains. The xanthine oxidase inhibitory activities of both complexes were evaluated.     

Syntheses,characterization, and crystal structures of two dinuclear nickel(II) and copper(II) complexes with Schiff bases

The phenolic azide bridged dinuclear nickel(II) complex, [Ni₂(L¹)₂(N₃)(H₂O)(μ_1,1-N₃)] · EtOH (I), and the thiocyanate bridged dinuclear copper(II) complex, [Cu₂(L²)₂(μ_1,1-NCS)₂] (II), where L¹ and L² are the deprotonated forms of 2-mothoxy-6-[(2-piperidin-1-ylethylimino)methyl]phenol and 2,4-dichloro-6-[(2-methylaminoethylimino)methyl]phenol, respectively, were synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. The crystal of I is orthorhombic: space group Pbca, a = 12.172(1), b = 20.953(1), c = 29.779(2) Å, V = 7594.8(9) ų, Z = 8. The crystal of II is monoclinic: space group P2₁/n, a = 8.7615(11), b = 19.672(2), c = 16.568(2) Å, β = 99.449(2)°, V = 2816.9(6) ų, Z = 4. The Ni atoms in I are in octahedral coordinations, and the Cu atoms in II are in square-pyramidal coordinations.     

Synthesis,crystal structures and properties of two copper(II) 2-aminomethylbenzimidazole complexes

Two new Cu^II complexes, [Cu(Hambi)₂(ClO₄)₂] and [Cu(Hambi)₂(dca)₂] (Hambi = 2-aminomethylbenzimidazole) have been prepared and characterized by X-ray diffraction, electronic paramagnetic resonance (e.p.r.) and i.r. analyses. Both complexes exhibit an elongated octahedral coordination environment with two Hambi ligands situated at the equatorial positions in a trans fashion [Cu—N bond distances range from 1.940(9) to 2.031(9) Å]. In the second complex, a new coordination mode, in which dicyanamide coordinates to copper(II) as a monodentate ligand with the amide nitrogen atom, was observed.     

Synthesis and X-ray crystal structures of two cobalt(III) complexes with Schiff bases

Two new mononuclear cobalt(III) complexes, [Co(MP)₂(N₃)] (I) and [Co(BP)₂]NO₃ · 2H₂O (II), where MP is 2-methoxy-6-[(2-morpholin-4-ylethylimino)methyl]phenolate and BP is 4-bromo-2-[(2-methylaminoethylimino)methyl]phenolate, were prepared and structurally characterized by physicochemical methods and single crystal X-ray diffraction. Both complexes crystallize in the monoclinic space group P2₁/c. For I: a = 10.3526(18), b = 25.371(4), c = 11.3585(19) Å, β = 101.529(8)°, V = 2923.1(8) ų, Z = 4; for II: a = 9.801(2), b = 27.183(3), c = 10.846(2) Å, β = 114.269(2)°, V = 2634.2(8) ų, Z = 4. An X-ray structural analysis indicates that in both complexes the Co atoms adopt octahedral coordination. The hindrance effects of the Schiff bases can influence the coordination of the secondary ligands such as azide.     

Syntheses,crystal structures and antibacterial activities of azido-bridged cobalt(III) complexes with Schiff bases

Two end-on azido-bridged Co(III) complexes, [Co₃(L1)₂(μ_1,1-N₃)₄(N₃)₂(OH₂)(OCH₂CH₃)]·0.5H₂O (1) and [Co₂(L2)₂(μ_1,1-N₃)₂(N₃)₂] (2), where L1 and L2 are the deprotonated form of 5-methoxy-2-[(2-morpholin-4-ylethylimino)methyl]phenol and 2-ethoxy-6-[(2-isopropylaminoethylimino)methyl]phenol, respectively, were prepared and structurally characterized by physicochemical and spectroscopic methods and single crystal X-ray determination. Complex (1) is a trinuclear Co compound, while complex (2) is a centrosymmetric dinuclear Co compound. In both complexes, the Co atoms are in octahedral coordination. The preliminary biological tests show that the complexes have excellent antibacterial activity.     

Synthesis,characterization and crystal structures of a pair of azido-bridged polynuclear Schiff base copper(II) complexes with urease inhibitory activity

A pair of azido-bridged Schiff base copper complexes, [CuL1(μ_1,3-N₃)] _n · nClO₄ (1) and [Cu₂(L2)₂(μ _1,1-N₃)₂] · 2ClO₄ (2) (L1 = N,N-diethyl-N′-(1-pyridin-2-ylmethylidene)ethane-1,2-diamine, L2 = N-isopropyl-N′-(1-pyridin-2-ylmethylidene)ethane-1,2-diamine) have been obtained by the same synthetic procedures, but with slightly different Schiff bases. The structures of the complexes have been characterized by IR spectra, elemental analysis, and single crystal X-ray determination. Each Cu atom in the complexes is five-coordinate in a square pyramidal configuration involving the three N atoms of the Schiff base ligand and two N atoms from two bridging azide ligands. The azide ligands adopt end-to-end bridging mode in (1), and end-on bridging mode in (2). The different coordination modes of the azide ligands in the two complexes are assigned to the steric effects of the terminal groups (two ethyl groups for (1) and one isopropyl group for (2)) in the Schiff base ligands. The urease inhibitory activities of the complexes were evaluated. Both of them showed potent inhibition against jack bean urease. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis, crystal structures, and magnetic properties of tetranuclear nickel(II) and copper(II) complexes with tridentate Schiff bases

Two cubane-type tetranuclear nickel(II) and copper(II) complexes, [Ni₄(L¹)₄(CH₃OH)₄] (1) and [Cu₄(L²)₄]·H₂O (2), where L¹ and L² are the dianionic forms of the tridentate Schiff bases 4-nitro-2-[(2-hydroxyethylimino)methyl]phenol (H₂L¹) and 5-methoxy-2-[(2-hydroxyethylimino)methyl]phenol (H₂L²), respectively, have been synthesized and characterized by physicochemical methods and single-crystal X-ray diffraction. The magnetic properties of the complexes show the presence of ferromagnetic interactions for complex 1 and antiferromagnetic interactions for complex 2, mediated by hydroxyl bridges.     

Synthesis,crystal structures and physical properties of two terephthalate-bridged copper(II) and nickel(II) complexes

Two ₂-terephthalate (tp) bridged complexes, [Cu₂(tp)(pren)₄](ClO₄)₂ (pren = 1,3-diaminopropane) (1) and [Ni₂(tp)(pren)₄(Him)₂](ClO₄)₂ (Him = imidazole) (2), have been synthesized and characterized by X-ray single-crystal structural analysis. In the discrete dinuclear [Cu₂(tp)(pren)₄]²⁺ cation of complex (1), each Cu^II atom has a square-pyramidal geometry, being coordinated by four nitrogen atoms (avg. 2.031 Å) from two pren ligands at the basal plane and one oxygen atom [2.259(3) Å] from a bis-monodentate tp group at the axial position. In the discrete dinuclear [Ni₂(tp)(pren)₄(Him)₂]²⁺ cation of complex (2), each Ni^II center is coordinated by five nitrogen atoms [Ni—N 2.069(3)–2.109(2) Å] from one Him group and two pren groups, and completed by one oxygen atom [Ni—O 2.138(3) Å] from a bis-monodentate tp group to furnish a distorted octahedron. Magnetic susceptibility studies show that the pair of metal atoms, although being separated by >11.5 Å, exhibit weak intramolecular antiferromagnetic interactions in complexes (1) (g = 2.07 and J = –3.4 cm^–1) and (2) (g = 2.10 and J = –0.7 cm^–1). The electrochemical behaviors of the complexes have also been studied by cyclic voltammogram processes.     

Synthesis, crystal structures and DNA-binding properties of two new mononuclear copper(II) complexes

Two mononuclear copper(II) complexes, [Cu(bpy)₂(CH₃OH)](pic)₂ (1) and [Cu(Me₂bpy)₂(H₂O)](pic)₂ (2) (bpy = 2,2′-bipyridine; Me₂bpy = 4,4′-dimethyl-2,2′-bipyridine; Hpic = 2,4,6-trinitrophenol), were synthesized and characterized by elemental analyses, conductivity measurements, IR, UV–Visible spectroscopy and single crystal X-ray analyses. Both complexes 1 and 2 are mononuclear compounds. The copper atom in complex 1 is in a distorted square pyramidal geometry with a CuN₄O chromophore as revealed from the τ value (0.25), while the Cu(II) ion in complex 2 displays a distorted trigonal bipyramidal stereochemistry with τ = 0.72. Hydrogen bonding interactions and π–π stacking interactions link the mononuclear copper complex 1 or 2 into a 1D infinite chain. The interactions of the two mononuclear complexes with herring sperm DNA (HS-DNA) have been studied by UV–visible absorption titration, fluorescence titration and ethidium bromide (EB) displacement experiments. The results suggest that both complexes might bind to DNA by intercalation.     

Preparation and characterization of copper(II) and nickel(II) complexes with novel tetraaza-macrocyclic schiff bases

Novel tetraaza-macrocycles with N-substituted carbamoyl groups were prepared by the reaction of 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,5,7,12-tetraene with isocyanates (RNCO, R = Ch₃ and C₆H₅). Their copper(II) and nickel(II) complexes were characterized by magnetic susceptibilities, electronic absorption spectra, and electrochemical properties. The complexing abilities and extractabilities of the ligands for the metal ions were investigated.     

Synthesis and crystal structures of cobalt(III) and zinc(II) complexes with Schiff bases

Two new cobalt(III) and zinc(II) complexes, [Co(L¹)₂ (H₂O)] · ClO₄ (I) and [Ni(L²)₂ (H₂O)₂] · 2ClO₄ (II), where L¹ is the deprotonated form of 5-methoxy-2-[(2-morpholin-4-ylethylimino)methyl]phenol, and L² is the zwitterionic form of 2-[(2-isopropylaminoethylimino)methyl]-5-methoxyphenol, were synthesized and structurally characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. The crystal of I is monoclinic: space group P2₁/c, a = 11.1512(4), b = 28.2424(11), c = 10.9655(4) Å, β = 95.746(2)°, V = 3436.1(2) ų, Z = 4. The crystal of II is triclinic: space group P2₁/c, a = 8.1441(2), b = 10.4531(3), c = 10.8849(3) Å, α = 84.0240(10)°, β = 76.9800(10)°, γ = 74.2280(10)°, V = 867.92(4) ų, Z = 1. Complex I consists of a mononuclear cobalt(III) complex cation and a perchlorate anion. Complex II consists of a crystallographic centrosymmetric mononuclear nickel(II) complex cation and two perchlorate anions. Each metal atom in the complexes is in an octahedral coordination.     

Electron spin resonance spectroscopy of copper(II) complexes with schiff bases as ligands

The ESR spectra of a series of Cu^II Schiff base complexes have been investigated in liquid and frozen solutions. The structures of these complexes are estimated on the basis of superhyperfine interactions and molecular orbital coefficients α² and β²₁ calculated from copper hyperfine parameters.     

Syntheses and crystal structures of two Schiff-base copper(II) complexes with urease inhibition

Two new copper(II) complexes, [CuL1(N₃)] (1) and [CuL2(NCS)] (2) (HL1 = 4-chloro-2-[(2-piperidin-1-ylethylimino)methyl]phenol, HL2 = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Complex 1 is an azide coordinated mononuclear complex, while complex 2 is a terminal thiocyanate coordinated mononuclear complex. The coppers in both complexes are four-coordinate, square-planar. Both complexes show potent urease inhibitory properties.     

Syntheses and crystal structures of two Schiff-base copper(II) complexes with antibacterial activities

Two structurally similar trinuclear complexes, [Cu(Cu(μ-Cl)₂L1)₂] (1) and [Cu(Cu(μ-Cl)₂L2)₂] (2) (HL1 = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol, HL2 = 1-[(2-piperidin-1ylethylimino)methyl]naphthalen-2-ol), have been synthesized and structurally characterized. Both complexes are bridged trinuclear compounds. The central Cu in each complex is in an octahedral environment with two phenolate and four bridging chlorides. The symmetry-related terminal Cu in each complex is square pyramidal with one phenolate oxygen, one imine nitrogen and one amine nitrogen of the Schiff-base ligand, one Cl^? in the basal plane, and one bridging Cl^? in the apical position. The complexes and Schiff bases were tested in vitro for their antibacterial activities.     

Synthesis and characterisation of copper(II), nickel(II) and palladium(II) complexes of some schiff bases of dehydroacetic acid

Summary Tri-and quadri-dentate Schiff bases have been synthesized from the reaction of dehydroacetic acid with diamines, aminoacids, aminophenols and aminoalcohols. The copper(II) and some nickel(II) and palladium(II) chelates of these ligands as well as copper(II) complexes of bidentate Schiff bases of dehydroacetic acid with anilines have been prepared and characterised by electronic, i.r. and n.m.r. spectral measurements and magnetic moments.