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 and crystal structures of Schiff base zinc(III) complexes with antibacterial activity

Two halide-coordinated zinc(II) complexes with the Schiff base 2-ethoxy-6-[(2-piperidin-1-ylethylimino)methyl]phenol were synthesized and structurally characterized by elemental analysis (C, H, N), FT-IR spectra, and single-crystal X-ray diffraction. The Zn atom in each complex is four-coordinated in a tetrahedral geometry by one phenolic O and one imine N atoms of the Schiff base ligand and by two halide atoms. The antibacterial activity of the complexes and the Schiff bases against the bacteria Staphylococcus aureus, Bacillus anthracis, Pseudomonas aeruginosa, and Streptococcus agalactiae was investigated.     

Synthesis and characterization of zinc(II) and cobalt(III) Schiff base complexes

Two mononuclear complexes with the Schiff base ligand 2-((2-(dimethylamino)ethylimino)methyl)phenol (HL), namely ZnL₂ and CoL₂(N₃), have been synthesized and characterized using single-crystal X-ray diffraction and spectroscopy (IR, ¹H NMR, UV–Vis, MS and EA). Both complexes are mononuclear. The coordination geometry in the Zn(II) complex is distorted square-pyramidal with a weak Zn···N interaction. The Co(III) complex is distorted octahedral, and the neutral molecule unit [Co^IIIL₂(N₃)] is connected by C–H···N hydrogen bonds to form a one-dimensional infinite chain. The luminescence of the zinc compound has been investigated. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Synthesis and crystal structures of two new Schiff base cobalt(II) and nickel(II) complexes

The Schiff base ligand (HL) obtained from phenylmethanamine and 5-methoxysalicylaldehyde are used as ligands for Co(II) and Ni(II) resulting in complexes [Co(L)₂] (I) and [Ni(L)₂] (II), and their solid state structures were determined by X-ray crystallography. In both complexes, weak interactions play an important role in the molecular self-assembly. Complex I was stacked up to the 2D layers by C-H…O hydrogen bonds and C-H…π interactions. In contrast, complex II was extended into 2D sheet by C-H…O hydrogen bonds, the C-H…π interactions, and edge-to-face interactions.     

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 antibacterial activities of Schiff base nickel(II) and cadmium(II) complexes with tridentate Schiff bases

Reaction of tridentate Schiff bases with nickel and cadmium salts in methanol afforded two new mononuclear complexes, [Ni(L¹)₂] (I) and [Cd(L²)₂] (II), where L¹ and L² are the anions of 2-bromo-4-chloro-6-[(3-dimethylaminopropylimino)methyl]phenol (HL¹) and 2-bromo-4-chloro-6-[(3-morpholin-4-ylpropylimino)methyl]phenol (HL²), respectively. The complexes were characterized by singlecrystal X-ray diffraction (CIF files CCDC nos. 1428653 (I) and 1428654 for (II)), FT-IR, and elemental analysis. Complex I crystallizes in the monoclinic space group P2 ₁/c, with a = 8.8216(8), b = 14.0424(8), c = 11.8687(12) Å, β = 111.238(2)°, V = 1370.4(2) ų, Z = 2. Complex II crystallizes in the monoclinic space group P2 ₁/n, with a = 9.6774(4), b = 15.8970(6), c = 20.3144(7) Å, β = 90.408(2)°, V = 3125.1(2) ų, Z = 4. The metal atoms in the complexes are coordinated by two tridentate Schiff base ligands, forming octahedral coordination. The free Schiff bases and the complexes were assayed for antibacterial activities. Both complexes are more active against the bacteria than the free Schiff bases. Complex II has the MIC value of 0.39 μg mL^–1 against Bacillus subtilis.     

Synthesis,characterization, and crystal structure of three cobalt(II) complexes with Schiff bases derived from rimantadine

By condensation of rimantadine and substituted salicylaldehyde, three new Schiff bases, HL¹, HL² and HL³, were synthesized. Then, a mixture of one of the new ligands and cobalt(II) chloride hexahydrate in ethanol led to 1, 2, and 3, respectively. These complexes were characterized by melting point, elemental analysis, infrared spectra, molar conductance, thermal analysis, and single-crystal X-ray diffraction analysis. X-ray diffraction analysis reveals that 1 crystallizes in the orthorhombic system, Pbcn space group; each asymmetric unit consists of one cobalt(II) ion, two deprotonated ligands, and one lattice water. The central cobalt is four coordinate via two nitrogens and two oxygens from the corresponding Schiff base ligand, forming a distorted tetrahedral geometry. Complexes 2 and 3 crystallize in the monoclinic system, P2₁/c space group; each asymmetric unit consists of one cobalt(II), two corresponding deprotonated ligands, one lattice water, and one methanol. The central cobalt is also four-coordinate via two nitrogens and two oxygens from the corresponding Schiff base ligand, forming a distorted tetrahedral geometry.     

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.     

Synthesis,X-ray crystal structures,and antibacterial activities of Schiff base nickel(II) complexes with similar tetradentate Schiff bases

Two new mononuclear complexes, [NiL¹] · CH₃OH (I) and [NiL²] (II), have been prepared from the tetradentate Schiff bases N,N'-bis(5-methylsalicylidene)ethylenediamine (H₂L¹) and N,N'-bis(5-methylsalicylidene)- o-phenylenediamine (H₂L₂), respectively. The complexes have been characterized by physico-chemical and spectroscopic methods, as well as single-crystal X-ray determination (CIF files nos. 1428969 (I), 1428968 (II)). Complex I crystallizes in the triclinic space group P1 with a = 6.7387(14), b = 10.7010(17), c = 12.681(2) Å, α = 87.059(2)°, β = 88.828(2)°, γ = 89.901(2)°, V = 913.0(3) ų, Z = 2. Complex II crystallizes in the monoclinic space group P2₁/n with a = 12.1437(11), b = 8.0537(8), c = 18.4545(18) Å, β = 105.088(2)°, V = 1742.7(3) ų, Z = 4. The nickel atoms in the complexes are coordinated by two phenolate O and two imine N atoms of the tetradentate Schiff base ligands, forming square planar coordination. The complexes and the Schiff base compounds were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method. As a result, the complexes showed effective antimicrobial activity against the microorganisms tested.     

Microwave-assisted synthesis,crystal structures,and in vitro antibacterial studies of zinc(II) and nickel(II) complexes with Schiff bases

The syntheses of a mononuclear zinc(II) complex [ZnCl(L¹)(Amp)] (I) and a mononuclear nickel(II) complex [Ni(L²)(HL²)](BF₄) · 0.5H₂O (II) (HL¹ = 4-methyl-2-[(4-methylpyridin-2-ylimino) methyl]phenol, HL² = 4-methyl-2-[(pyridin-2-ylmethylimino)methyl]phenol; Amp = 2-amino-4- methylpyridine) were prepared under microwave irradiation. The complexes were characterized by a combination of elemental analyses, and IR and electronic spectra. Their structures were further confirmed by single crystal X-ray crystallography (СIF files CCDC nos 1437737 (I), 1437738 (II)). The Zn atom in the monomeric complex I is in tetrahedral coordination. The Ni atoms in the dimeric complex II are in octahedral coordination. Crystals of the complexes are stabilized by hydrogen bonds. In order to evaluate the biological activity of the complexes, in vitro antibacterial against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa was assayed. The complexes have strong activity against Bacillus subtilis.     

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, structures, and antimicrobial activity of nickel(II) and zinc(II) complexes with Schiff bases derived from 3-bromosalicylaldehyde

The Schiff bases 2-bromo-6-[(3-cyclohexylaminopropylimino)methyl]phenol (HCMP) and 2-bromo-6-[(3-dimethylaminopropylimino)methyl]phenol (HDMP) derived from 3-bromosalicylaldehyde with N-cyclohexylpropane-1,3-diamine and N,N-dimethylpropane-1,3-diamine, respectively, and their nickel(II) and zinc(II) complexes [Ni(CMP)₂] (I) and [ZnCl₂(HDMP)] (II) have been prepared and characterized by elemental analyses, IR, and single crystal X-ray crystallographic determination. The crystal of I is monoclinic: space group P2₁/c, a = 12.0304(6), b = 13.1594(6), c = 10.2445(5) Å, β = 101.019(1)°, V = 1591.9(1) ų, Z = 2. The crystal of II is monoclinic: space group C2/c, a = 22.286(5), b = 12.210(3), c = 14.513(3) Å, β = 124.118(3)°, V = 3269.5(13) ų, Z = 8. The Schiff base HCMP coordinates to the Ni atom through the phenolate O, imine N, and amine N atoms, while the Schiff base HDMP coordinates to the Zn atom through the phenolate O and imine N atoms. The effect of these complexes on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans were studied.     

Synthesis,characterization and biological studies of cobalt(II) and nickel(II) complexes with new Schiff bases

Complexes of CoII and NiII with new Schiff bases derived from 4-amino-5-sulfanyl-1,2,4-triazoles and glyoxal, biacetyl or benzil have been prepared. All have the stoichiometry ML(H2O)2, with L coordination via the two imine nitrogens and two thiolato sulfurs in an overall octahedral geometry.Some of the complexes were screened for their antibacterial and antifungal activity, and one representative CoII complex was evaluated for oxytocic activity.     

Copper(II) complexes with neutral Schiff bases: Syntheses, crystal structures and DNA interactions

The synthesis and X-ray structural characterisation of a new Cu(II) complex, [Cu(L¹)Cl](ClO₄)·CH₃OH (1) [L¹ = N,N′-bis((pyridine-2-yl)phenylidene)-1,3-diaminopropan-2-ol], has been described in this work. The structural study reveals that the Cu(II) centre in 1 has a square pyramidal geometry with a trigonality index τ = 0.43, being coordinated by the organic ligand and a chloro group. The interaction of complex 1 and another complex previously reported by our group, [Cu(L²)](ClO₄)₂ (2) [L² = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-ylphenylidene)amino]ethyl}amino)ethyl]ethane-1,2diamine], with calf thymus DNA (CT-DNA) has been investigated using absorption and emission spectral studies. The binding constant (K_b) and the linear Stern-Volmer quenching constant (K_sv) have been determined.     

Thermal analysis of pentafluorophenyl organo complexes of cobalt(III) with Schiff bases

A series of complexes of the type (C₆F₅)ConLL ₄B with tetradentate ligands (L ₄=acacen (N,N'-ethylene-bis acetylacetoneiminate dianion), mesalen (N,N'-ethylene-bis-7, 7'-dimethylsalicylideneiminate dianion);B=H₂O, NH₃,py,ba, pip, en andL ₄=dotH (diacetylmonoximeiminodiacetyl-monoximateiminopropane-1,3 monoanion),B== Br, I, CN) has been studied, using TG and DTA methods to obtain information concerning the decomposition mechanism and the influence of the ligands on the thermal stabilities of cobalt-carbon and cobalt-axial base bond.The elimination of the axial base leads to the formation of pentacoordinate complexes (C₆F₅)CoL ₄ (whenL ₄=acacen, mesalen) and their subsequent decomposition involves cobalt-carbon bond rupture to form CoL ₄. In contrast, the latter reaction occurs first when the tetradentate ligand is dotnH.It has been observed that the stability of the cobalt-carbon bond is related to the nature of the equatorial ligands, and decreases in the order: mesalen > acacen > dotnH.

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Zusammenfassung Eine Reihe von Komplexen des Type (C₆F₅)CoL ₄ B mit Tetradentat-Liganden (L ₄=Acacen(N-N'Äthylen-bis-Acetylacetoniminat-Dianion), Mesalen (N-N'Äthylen-bis-7-7'-Dimethylsalycilideniminat-Dianion);B= H₂O, NH₃,py, ba, pip, en undL ₄== dotnH (Diacetylmonoxym-imino-diacetylmonoxymat-iminopropan 1,3 Monoanion)B== Br, I, CN) wurde mittels TG und DTA Methoden untersucht, um Informationen bezüglich des Zersetzungsmechanismus und des Einflusses der Eiganden auf die thermische Stabilität von Cobalt-Kohlenstoff- und Cobalt Axialbasenbindungen zu erhalten.Die Eliminierung der axialen Base führt zur Bildung von Pentakoordinat-Komplexen (C₆F₅)CoL ₄ (wobeiL ₄=Acacen, Mesalen) und ihre darauffolgende Zersetzung ist mit der Spaltung der Cobalt-Kohlenstoffbindung verbunden unter Bildung von CoL ₄. Im Gegensatz hierzu verläuft die letztere Reaktion zuerst, falls der Tetradentat-Ligand dotnH ist.Es wurde beobachtet, daß die Stabilität von Kobalt-Kohlenstoffbindungen von der Art der äquatorialen Liganden abhängig ist und in der Reihenfolge Mesalen > Acacen > dotnH abnimmt.

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Résumé Afin d'obtenir des données sur le mécanisme de décomposition et l'influence des ligands sur la stabilité thermique des liaisons à base axiale cobalt et carbone-cobalt, on a étudié par TG et ATD une série de complexes du type (C₆F₅)CoL ₄B, avec des ligands tétradentés (L ₄=acasène, mésalène;B=H₂O, NH₃,py, ba, pip, en etL ₄= dotnH,B=Br, I, CN).L'élimination de la base axiale conduit à la formation de complexes pentacoordinés (C₆F₅)CoL ₄ (oùL ₄=acacène, mésalène) et leur décomposition subséquente fait intervenir la rupture de la liaison cobalt-carbone pour former CoL ₄. Cette dernière réaction intervient au contraire en premier lieu si le ligand tétradenté est dotnH.On a observé que la stabilité de la liaison cobalt-carbone est en rapport avec la nature des ligands équatoriaux et diminue dans l'ordre suivant: mésalène > acacène > dotnH.

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(C₆F₅)CoL ₄B (L₄= - N,N- - , — N,N -7,7- );N,N-7,7- ); =₂, NH₃, , ba, pip, en L₄=dotnH - ---1,3; =, I, CN) , , - . - (C₆F₅)CoL₄ L₄=, , - - CoL₄. , , dotnH. , - > > dotnH.

     

Synthesis,structures, and antibacterial activities of two iron(III) complexes with Schiff bases

Two Schiff base iron(III) complexes, [FeL¹(AHA)] · H₂O (I) and [Fe(L²)₂] · ClO₄ (II), where AHA is the deprotonated form of acetohydroxamic acid, and L¹ and L² are the anionic form of N,N′-bis(3-ethoxysalicylidene)propane-1,2-diamine and 2-[1-(2-aminopropylimino)ethyl]phenol, respectively, have been synthesized and characterized by physical chemical methods and single crystal X-ray diffraction. Crystallographic data for I: orthorhombic, space group Iba2, a = 20.781(3), b = 23.527(3), c = 10.071(2) Å, V = 4923.7(12) ų, Z = 8, R ₁ = 0.0374, wR ₂ = 0.0900. Crystallographic data for II: triclinic, space group a = 12.748(1), b = 13.401(1), c = 19.007(1) Å, α = 106.623(2)°, β = 97.462(2)°, γ = 112.543(2)°, V = 2784.9(4) ų, Z = 4, R ₁ = 0.0892, wR ₂ = 0.2434. X-ray crystal structural study indicated that the coordination environment around each Fe atom in the complexes is a six-coordinated distorted octahedron. The antibacterial activities of the complexes were assayed.     

Synthesis,characterization, and crystal structures of two Schiff base zinc(II) complexes with urease inhibitory activities

Two Schiff base zinc(II) complexes, [ZnBr₂L¹] · 2CH₃OH (I) (I) and [ZnBr₂L²] (II), where L¹ is 4-chloro-2-[(2-piperazin-1-ylethylimino)methyl]phenol and L² is 4-chloro-2-[(3-diethylaminopropylimino)methyl]phenol were synthesized and structurally characterized. The crystal of I is monoclinic: space group P2₁/c, a = 9.831(3), b = 18.680(6), c = 11.879(4) Å, β = 94.660(6)°, V = 2174.3(11) ų, Z = 4. The crystal of II is monoclinic: space group P2₁/n, a = 7.2310(14), b = 16.037(3), c = 15.856(3), β = 90.01(3)°, V = 1838.7(6) ų, Z = 4. The Zn atom in each complex is four-coordinated by one phenolate O and one imine N atoms of the Schiff base ligand and two bromide atoms, forming a tetrahedral coordination. The urease inhibitory activities of the complexes were evaluated.