Dioxime Ligand Research Articles

Synthesis and Structural and Biochemical Activity Studies of Dioxime Ligand and its Mononuclear Cu(II), Ni(II), and Co(II) Complexes

A new tetradentate ligand incorporating dioxime moities has been synthesized. Its copper(II), nickel(II), and cobalt(II) complexes have been prepared and characterized by spectral methods. Elemental analyses and spectroscopic data of the metal complexes are consistent with the formation of the mononuclear copper(II), nickel(II) and cobalt(II) complexes. The crystal structure of the (2E, 2′E)-butane-2,3-dione 2,2′-{O 2,O 2′-[1,2-phenylenebis(methylene)]oxime compound (3) was determined by single-crystal x-ray diffraction technique. The free ligand and copper(II), nickel(II), and cobalt(II) complexes (5–7) were tested against the morphology of series bacteria. The Cu(II), Ni(II), and Co(II) complexes exhibit higher activity than dioxime ligand under identical experimental conditions.

Synthesis and Structural Studies of Hydrazone Dioxime Ligand and Its Cu(II) and Ni(II) Complexes

A hydrazone oxime (H2L) has been prepared in EtOH by reacting 2-hydrazine hydrate (2) with 2,3-butanedione monoxime (1). Homodinuclear copper(II), nickel(II), homotetranuclear copper(II), and heterotetranuclear copper(II)–nickel(II) complexes of H2L have been prepared. The metal complexes have been characterized by elemental analyses, magnetic moments, infrared (IR), ultraviolet–visible (UV-vis), and mass and thermal analyses studies. The dinuclear copper(II) and nickel(II) complexes of H2L were found to have a 1:1 metal:ligand ratio. In addition, total energy and heat formation for ligands (H2L and DHyLH2) by semiempirical PM3 calculations have shown that H2L is more stable than DHyLH2.

One-dimensional and two-dimensional Zn(II) and Cd(II) sulfates with bipyridine and dioxime ligands

One-dimensional and two-dimensional Zn(II) and Cd(II) sulfates with bipyridine and dioxime ligands

Polymeric Zn(II) and Cd(II) Sulfates with Bipyridine and Dioxime Ligands: Supramolecular Isomerism, Chirality, and Luminescence

The interaction of zinc(II) or cadmium(II) sulfate with 4,4′-bipyridine (bpy) or 4,4′-bipyridinethane (bpe) in the presence of 1,2-cyclohexanedionedioxime (NioxH2) resulted in four novel polymeric compounds with the compositions {[Zn(H2O)6][Zn(SO4)2(H2O)2(bpy)][Zn(SO4)(H2O)3(bpy)]}∞ (1), {[Zn(SO4)(NioxH2)(bpy)]·0.5H2O·DMF}∞ (DMF = N,N-dimethylformamide) (2), [Zn(SO4)(NioxH2)(bpe)]∞ (3), and [Cd(SO4)(NioxH2)(bpe)]∞ (4). Compounds were characterized by spectroscopic techniques and single crystal X-ray method. The chiral layer coordination polymer is the robust structural motif in 2–4. Although compounds 3 and 4 were isolated in the same crystallization conditions, the layers of opposite chirality constitute the achiral (3), and the layers of the same chirality result in chiral (4) architectures. All materials display blue luminescence upon excitation with ultraviolet light.

Copper(II) coordination chain complexes with the 3,5-diacetyl-4-methylpyrazole dioxime ligand: Synthesis, crystal structures and magnetic properties

3,5-Diacetyl-4-methylpyrazole dioxime (dampdoH 3) has been found to form with copper(II), in the presence of different anions (perchlorate, nitrate, triflate and tetrafluoroborate), four new dimeric complexes, [Cu 2(dampdoH 2) 2(ClO 4) 2] ( 1); [Cu 2(dampdoH 2) 2(H 2O) 2]2NO 3 ( 2); [Cu 2(dampdoH 2) 2(CF 3SO 3) 2] ( 3) and [Cu 2(dampdoH 2) 2(BF 4) 2] ( 4). The molecular structure of [Cu 2(dampdoH 3) 2] 2+ which is the common unit for the four complexes is composed of binuclear species where one of the oxime functions has the classical structure while the second function has a zwitterionic structure. For the four complexes these binuclear units are parallel and are bound together by a strong intermolecular bond to create an infinite 1D chain expanding along the crystallographic “ a” axis. Variable-temperature magnetic susceptibility measurements for complex 1 indicate a very strong antiferromagnetic exchange coupling intra or/and interdimeric ring, the J 1 value of the intradimer coupling being strongest than the interbinuclear coupling J 2 ( J 1 = −346 cm −1, J 2 = −119.15 cm −1).

Synthesis, characterization, DNA binding and cleavage studies of Ru(II) complexes containing oxime ligands

The Ru(II) precursors, [RuHCl(CO)(EPh 3) 3] (E = P or As) when reacted with some well known monoxime and dioxime ligands in ethanolic solution afforded the new complexes of the types [RuCl(CO)(EPh 3) 2L1], [RuH(CO)(EPh 3) 2L2] and [RuCl(CO)(EPh 3) 2L3] ((H 1L1) = diacetylmonoxime, (H 1L2) = dimethylglyoxime and (H 2L3) = benzoiloxime). The ligands coordinated in a bidentate chelate mode forming a five membered chelate ring. The molecular structures of two of the complexes have been determined by single crystal X-ray diffraction study. The structural determination confirms the deprotonation of the oxime function. Examination of all the complexes by cyclic voltammetry showed the occurrence of some quasi-reversible redox reactions owing to changes in the oxidation state of the central metal atoms. Structural assignments are supported by combination of IR, UV–Vis, 1H NMR and elemental analyses. In addition, the DNA binding properties and cleavage efficiency of new complexes have been tested.

Hexanuclear copper(ii) cage with {Cu3O⋯H⋯OCu3} core supported by a dicompartmental oxime ligand with m-xylyl spacer: synthesis, molecular structure and magnetic studies

A new dicompartmental dioxime ligand (H(2)L) with m-xylyl spacer between the donor sites has been synthesised by Schiff-base condensation of α,α'-diamino-m-xylene and diacetyl monooxime. The ligand reacts with copper(ii) salts giving rise to hexanuclear tricationic copper(II) cage complexes [Cu(II)(6)(μ(3)-O···H···O-μ(3))L(3)(H(2)O)(6)]X(3) (X = BF(4), 1a; X = ClO(4), 1b). The complexes have been characterised by different analytical and spectroscopic techniques and confirmed the hexanuclear structure even in solution. Single crystal X-ray diffraction studies of both the complexes revealed a very similar core structure with three dicompartmental ligands supporting two triangular Cu(3)O cores that share a proton, located on their common threefold axis and involved in a strong hydrogen bond interaction (O···O distance of 2.517(2) Å). Two Cu(3)O units do not superimpose but are staggered and disposed with the formation of a helicate structure. However both the enantiomers are present in the centrosymmetric space group. The facing Cu(3)-planes in 1a are separated at a distance of 3.476 Å. The temperature dependence of the magnetic behaviour of the hexanuclear complex 1a clearly indicates an overall antiferromagnetic exchange interaction between the spin carriers in the cage having two Cu(3)O subunits and leaves a single unpaired electron in each triangular unit. The unpaired electrons in the two Cu(3)O units interact antiferromagnetically through hydrogen bonding giving rise to an overall singlet-spin ground state.

Copper(II) and Nickel(II) Complexes of β-Aminoketoxime Ligand: Syntheses, Crystal Structures, Magnetism, and Nickel(II) Templated Coupling of Oxime with Nitrile

The syntheses, molecular structures, and magnetic properties of a dicopper(II) complex, [Cu(2)(HL(1))(2)](ClO(4))(2) (1), and its nickel(II) analog, [Ni(2)(HL(1))(2)](ClO(4))(2) (2), of a beta-amino ketoxime ligand (H(2)L(1) = 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dioxime) are discussed. The metal centers in out-of-plane oximate bridged dinuclear complexes (1 and 2) display distorted trigonal bipyramidal geometry and form a six-membered M(2)(NO)(2) ring oriented in a boat conformation. The two copper(II) centers in 1 interact ferromagnetically giving rise to a triplet-spin ground state whereas the two nickel(II) centers in 2 interact antiferromagnetically to stabilize a singlet-spin state. Variable temperature magnetic susceptibility measurements establish the presence of a weak ferromagnetic coupling (J = 13 cm(-1)) in 1 and a weak anitiferromagnetic coupling (J = -12 cm(-1)) in 2. The exchange coupling constant derived from B3LYP computations in conjunction with broken symmetry spin-projection techniques for the oximate bridged dinuclear copper(II) complex shows excellent agreement with the corresponding experimental value. A square-planar mononuclear nickel(II) complex of the dioxime ligand, [Ni(H(2)L(1))](ClO(4))(2) (3), is reported along with its crystal structure, which reacts with acetonitrile to produce a six-coordinate mononuclear complex, [Ni(L(2))](ClO(4))(2) (4). The ligand (L(2)) in complex 4 is the iminoacyl derivative of oxime, where the coupling of oxime and acetonitrile takes place via a proton-assisted pathway. The iminoacylation of H(2)L(1) works with other nitriles like butyronitrile and benzonitrile. Computational studies support a proton-assisted coupling of oxime with nitrile. The critical transition states have been located for the iminoacylation reaction. Complex 4 can be converted back to complex 3 by reacting with sodium acetate in methanol.

Weak interactions between furfuryl and equatorial dioxime ligand in furfuryl(O2)Co(dmgH)2Py: NMR, X-ray and DFT calculations

Abstract The crystal and molecular structure of furfuryl(O2)Co(dmgH)2Py (1) has been determined by X-ray diffraction analysis. In the molecular structure of 1, the furfuryl ring oxygen is pointing inwards and is very close to one of the dmgH (Me) (2.625 A). It shows unusual C–H···O weak interaction which must be responsible for the observed 1:3 ratio of dmgH methyl protons in NMR spectrum. Also, theoretical calculations using DFT have been performed on 1 for the Co–O and CH2–C(furfuryl) bond rotation. Conformational energy diagrams derived from theoretical calculations also indicate that in most stable conformer the furfuryl ring oxygen is very close to one of the dmgH (Me) groups.

Anion-Induced Generation of Binuclear and Polymeric Cd(II) and Zn(II) Coordination Compounds with 4,4′-Bipyridine and Dioxime Ligands

Interaction of zinc or cadmium formate or acetate with 1,2-cyclohexanedionedioxime (NioxH2) and 4,4′-bipyridine (bpy) resulted in similar binuclear coordination compounds of the general formula [M2(NioxH2)2(X)4(H2O)2(bpy)], where M = Cd and X = HCOO− for 1; M = Zn, Cd and X = CH3COO− for 2 and 3, respectively. When the corresponding sulfate salts were used as precursors in the synthesis, a dioxime-containing one-dimensional (1D) coordination polymer with the chemical formula [Cd(NioxH2)(SO4)·(bpy)](NioxH2)·(H2O)3 (4) was obtained with Cd. All compounds were characterized by X-ray diffraction and spectroscopic techniques, and the thermogravimetric data are presented solely for compound 4. The experimental results demonstrate the successful strategy of using “metal oxime” building blocks in order to design new multinuclear complexes. The study has shown that the geometry and size of the corresponding anions together with their coordinating and hydrogen-bonding properties are essential in determining the final structures.

Homo‐ and heteropolynuclear copper(II) complexes containing a new diimine–dioxime ligand and 1,10‐phenanthroline: synthesis, characterization, solvent‐extraction studies, catalase‐like functions and DNA cleavage abilities

AbstractA series of homo‐, heterodinuclear and homotrinuclear copper(II) complexes containing a new Schiff base ligand and 1,10‐phenanthroline were synthesized. Based on results of elemental analyses, FTIR, 1H‐ and 13C‐NMR spectra, conductivity measurements and magnetic susceptibility measurements, the complexes had general compositions {[Cu(L)(H2O)M(phen)2](ClO4)2 [M = Cu(II), Mn(II), Co(II)]} and {[Cu3(L)2(H2O)2](ClO4)2}. The metal:L:phen ratio is 2:1:2 for the dinuclear copper(II) complexes and the metal:L ratio was 3:2 for the trinuclear copper(II) complex. The liquid–liquid extraction of various transition metal cations [Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), Cd(II), Hg(II)] from the aqueous phase to the organic phase was carried out using the diimine–dioxime ligand. It was concluded that the ligand can effectively be used in solvent extraction of copper(II) from the aqueous phase to the organic phase. Furthermore, catalytic activitiy of the complexes for the disproportionation of hydrogen peroxide was also investigated in the presence of imidazole. Dinuclear copper(II)–manganese(II) complex has some similarity to manganese catalase in structure and activity. The interaction between these complexes and DNA has also been investigated by agarose gel electrophoresis; we found that the homo‐ and heterodinuclear copper complexes can cleave supercoiled pBR322 DNA to nicked and linear forms in the presence of H2O2. Copyright © 2009 John Wiley & Sons, Ltd.

Synthesis, characterization, catalase functions and DNA cleavage studies of new homo and heteronuclear Schiff base copper(II) complexes

A new tetradentate diimine–dioxime ligand containing a donor set of N 4, and its homo-, heterodinuclear and homotrinuclear copper(II) complexes were prepared and characterized on the basis of their elemental analysis, FT-IR, 1H and 13C NMR spectra, molar conductivity and magnetic moment measurements. The extraction ability of N,N′′-bis[1-biphenyl-2-hydroxyimino-1-ethylidene]-diethylenetriamine was also evaluated in chloroform by using several transition metal picrates such as Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), Cd(II) and Hg(II). It has been seen that the ligand shows strong binding ability toward the copper(II) ion. Moreover, the catalytic activities of the complexes for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The synthesized complexes display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity. The interaction between these complexes and DNA has also been investigated by agarose gel electrophoresis. We found that the homo- and heterodinuclear copper complexes can cleave supercoiled pBR322 DNA to nicked and linear forms. The dinuclear complexes including phenanthroline ( 2– 4), with H 2O 2 as a co-oxidant, exhibited the strongest cleaving activity.

Manganese(II) Trimeric Systems Derived from Pyridyldioximato Ligands: Synthesis, Crystal Structure, and Magnetic Characterization

AbstractThree new manganese compounds have been obtained by reaction of the 2,6‐diacetylpyridine dioxime (dapdoH2) ligand with several MnII salts. By using a variety of manganese(II) carboxylates, three MnII derivatives with general formula [Mn3(RCOO)6(dapdoH2)2], where RCOO– = formate (1), acetate (2), and benzoate (3), were obtained. Structural analysis reveals chains of trinuclear units for 1 and isolated trinuclear molecules for 2. Compound 1 provides an example of a new topology for the [Mn3(RCOO)6(L)2] general formula. Magnetic susceptibility studies reveal topological ferrimagnetism for 1 and conventional antiferromagnetic response for 2 and 3, with coupling constants of –3.1, –3.2, and –1.4 cm–1 inside the trimeric units of 1, 2, and 3, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Tris(oxamide dioxime-κN,N')nickel(II) sulfate penta-hydrate.

The asymmetric unit of the title compound, [Ni(C2H6N4O2)3]SO4·5H2O, contains two complex cations, two sulfate anions and ten lattice water mol­ecules. In both independent cations, the central NiII ion adopts a distorted octa­hedral coordination involving six imino N atoms of three bidentate oxamide dioxime ligands. The bulk structure is achieved by a three-dimensional network of O—H⋯O and N—H⋯O hydrogen bonds which inter­link the ionic partners and some water mol­ecules in such a manner that the lattice framework thus formed defines channels parallel to [100]. The other water mol­ecules are lodged inside these channels. Two of the ten water mol­ecules in the asymmetric unit are disordered over three sites, in 0.356 (3):0.324 (5):0.320 (5) and 0.247 (3):0.293 (6):0.460 (6) occupancy ratios, and one O atom of a sulfate ion is also disordered over two sites, with occupancies of 0.621 (5) and 0.379 (5).

A new vic-dioxime ligand containing two azo substituents and its mononuclear nickel(II), cobalt(II), and copper(II) complexes; synthesis, characterization, spectroscopic and biological studies

A new vicinal dioxime ligand containing azo and thione chromophores, namely 1,3-bis[4-(phenyldiazenyl)phenyl]-2-thiooxaimidazoline-4,5-dione dioxime (bppH2), was synthesized by the reaction of cyanogen di-N-oxide with N,N′-bis(4-phenylazophenyl) thiourea in dichloromethane solution at −10 °C. Mononuclear complexes of bppH2 with nickel(II), cobalt(II), and copper(II) were synthesized. The complexes, [Ni(bppH)2], [Cu(bppH)2], and [Co(bppH)2] were characterized by several techniques using elemental analyses, conductivity measurements, FT-IR, and electronic spectral studies. The data suggest that the ligand coordinates through the N,N atoms, as do most vic-dioximes. The molar conductivities in DMF solution indicate nonelectrolytic nature for the complexes. Antimicrobial activities of the ligand and its metal complexes were estimated for five bacteria, namely Klebsiella pneumoniae, Micrococcus luteus, Mycobacterium smegmatis, Enterobacter cloaca and Bacillus megaterium and three fungi, namely Candida albicans, Kluyveromyces marxianus, and Rhodotorula rubra.

A vic -dioxime ligand bearing fluorescent coumarin moieties and its complexes; preparation, spectroscopy, and electrochemistry

The synthesis of a new vic-dioxime ligand, N,N′2-dihydroxy-O 1,O 2-bis(4-methyl-2-oxo-2H-chromen-7-yl)oxalimidamid (LH2) (1), bearing functional coumarins and its soluble mono- {Ni(II), Cu(II), Co(II)} and dinuclear {UO2(II)} complexes are presented. The fluorescence properties due to the 7-hydroxy-4-methylcoumarin fluorophore, which is conjugated with vic-dioxime that functions as the MN4 core of 1 and its complexes, are also reported. The formation of coordination complexes resulted in the blue shift in excitation spectrum and fluorescence quenching of 1. Both mononuclear {(LH)2M, M=Ni(II), Cu(II), and Co(II)} and homodinuclear {(LH)2(UO2)2(OH)2)} complexes have been obtained with metal : ligand ratios of 1 : 2 and 2 : 2, respectively. The characterizations of the new compounds were made by elemental analysis, 1H-NMR, FT-IR, UV-Vis, and LCMS data. Redox behavior of 1, involving oxime and coumarin moieties, and its complexes with Ni(II), Cu(II), Co(II) and UO2(II) were investigated by cyclic voltammetry. The comparison of the electrochemical behavior of 1 with its complexes enabled us to identify metal-, oxime- and coumarin-based signals.

An oximate-based hexanuclear mixed-valence MnIII4MnII2 edge-sharing bitetrahedral core with an St = 5 spin ground state

The synthesis, structures and magnetic properties of two hexanuclear Mn6 clusters are reported: Mn6(mu4-O)2(dapdo)2(dapdoH)4(mu2-OH)2](ClO4)(2).6MeCN (1.6MeCN) and [Mn6(mu4-O)2(dapdo)2(dapdoH)4(mu2-OCH3)2](ClO4)(2).2Et2O (2.2Et2O) [dapdo2- is the dianion of 2,6-diacetylpyridine dioxime and dapdoH- is the monoanion of the aforesaid dioxime ligand]. Both complexes are mixed-valent with two Mn(II) and four Mn(III) atoms disposed in an edge-sharing bitetrahedral core. Both complexes 1 and 2 display the same [Mn(III)4Mn(II)2(mu4-O)2(mu2-OR)2]10+ core in which R = H for 1 and R = Me for 2. The [Mn(III)4Mn(II)2] core is rather uncommon compared to the reported [Mn(III)2Mn(II)4] core in the literature. DC magnetic susceptibility measurements on 1 and 2 reveal the presence of competing exchange interactions resulting in an St = 5 ground spin state. The magnetic behavior of the compounds indicates antiferromagnetic coupling between the manganese(III) centers, whereas the coupling between the manganese(III) and manganese(II) is weakly antiferromagnetic or ferromagnetic depending on the bridging environments. Finally the interaction between the manganese(II) centers from the two fused tetrahedra is weakly ferromagnetic in nature stabilizing St = 5 ground spin state in compounds 1 and 2.

A new cobalodioxime and its three levels of H-bondings to 1D helical strand, 2D helices and 3D framework

An octahedral cobalodioxime of a new tetradentate dioxime ligand, 3,8-dimethyl-4,7-diazadeca-3,7-diene-2,9-dionedioxime (LH 2) and its unprecedented H-bonded self-assembling have been reported. The diamagnetic bioinorganic Cl 2Co(LH) ( 1) unit of zero dimensions assembles to infinite 1D helical strand by novel head-on H-bonding helices. Interstrand facial H-bonding results the 2D helices and interhelices lateral H-bonding (oxime–oxime and Cl–H(CH 2)) constructs the 3D framework. The H-bonding effect has been established in solution also and investigated by 1H NMR spectra in DMSO- d 6 and CDCl 3 solvents.

( E, E) S, S′-bis(2-benzimidazolylmethyl) dithioglyoxime, synthesis and characterization of heterotrinuclear complexes of and determination of their metal contents by EDXRF analysis

A vicinal dioxime ligand with two 2-benzimidazolylmethyl groups, namely S, S′-bis(2-benzimidazolylmethyl) dithioglyoxine (H 2L) and its axially pyridine and 2,6-dimethyl pyridine bonded Co(III) complexes were prepared according to prior literature [Y. Gök, S.Z. Yıldız, Synth. React. Inorg. Met-Org. Chem. 22 (9) (1992) 1327]. BF 2 + bridged Co(III) complexes have been synthesized via the hydrogen-bridged Co(III) complexes by using borontrifloride ethyl ether complex. Heterotrinuclear complexes have been prepared by the reaction of these more soluble BF 2–capped Co(III) complexes with stoichiometric amount of CdCl 2 · H 2O and NiCl 2 · 6H 2O salts. Using 1H, 13C NMR, IR and MS spectral data and elemental analysis, the structures of the complexes were identified. Qualitative and quantitative determination of Co, Ni and Cd contents of the heterotrinuclear complexes have been investigated by energy dispersive X-ray fluorescence (EDXRF) method. An annular 50 mCi 241Am radioactive source emitting 59.543 keV photons was used for excitation and Si(Li) detector having 157 eV FWHM at 5.9 keV was used for intensity measurements.

Synthesis and Characterization of a Novel Quinoxaline-Substituted vic-Dioxime and Its Complexes Containing Bis(12-Diazacrown-4) Derivatives

Abstract A new quinoxaline-substituted vicinal dioxime ligand containing bis(12-diazacrown-4) units (H2L) was synthesized by the reaction of cyanogen di-N-oxide with compound 4. Mononuclear NiII and CuII complexes with a metal:ligand ratio of 1:2 for H2L and a trinuclear CuII complex were also synthesized. The mononuclear CuII species coordinated to two CuII ions through the deprotonated oximate oxygens to yield a trinuclear structure cis-bridged by the oximate groups, with 1,10-phenanthroline as an end-cap ligand. The mononuclear CoIII complex of H2L was isolated with pyridine and chlorine as axial ligands. In addition, a CoIII complex containing the BF2+ bridge macrocycle was synthesized using a precursor hydrogen-bridged CoIII complex via a template effect. The extraction abilities of 1, 3, and 11 were also evaluated in 1,2-dichloroethane by using several alkali (Li+, Na+, K+, and Cs+) and transition-metal picrates, such as Ag+, Pb2+, Cd2+, Cu2+, and Zn2+. Structures of the ligands and metal complexes were solved by elemental analyses, 1H and 13C NMR, FT-IR, UV–vis, and mass spectra.