Ali El-Dissouky

Synthesis, characterization, and biological activity studies of copper(II)–metal(II) binuclear complexes of dipyridylglyoxal bis(2-hydroxybenzoyl hydrazone)

A new series of copper(II) mononuclear and copper(II)–metal(II) binuclear complexes [(H2L)Cu] ⋅ H2O, [CuLM] ⋅ nH2O, and [Cu(H2L)M(OAc)2] ⋅ nH2O, n = 1–2, M = Co(II), Ni(II), Cu(II), or Zn(II), and L is the anion of dipyridylglyoxal bis(2-hydroxybenzoyl hydrazone), H4L, were synthesized and characterized. Elemental analyses, molar conductivities, and FT-IR spectra support the formulation of these complexes. IR data suggest that H4L is dibasic tetradentate in [(H2L)Cu] ⋅ H2O and [Cu(H2L)M(OAc)2] ⋅ nH2O but tetrabasic hexadentate in [CuLM] ⋅ nH2O (n = 1–2). Thermal studies indicate that waters are of crystallization and the complexes are thermally stable to 347–402°C depending upon the nature of the complex. Magnetic moment values indicate magnetic exchange interaction between Cu(II) and M(II) centers in binuclear complexes. The electronic spectral data show that d–d transitions of CuN2O2 in the mononuclear complex are blue shifted in binuclear complexes in the sequences: Cu–Cu > Cu–Ni > Cu–Co > Cu–Zn, suggesting that the binuclear complexes [CuLM] ⋅ nH2O are more planar than the mononuclear complex. The structures of complexes were optimized through molecular mechanics applying MM +force field coupled with molecular dynamics simulation. [(H2L)Cu] ⋅ nH2O, [CuLM] ⋅ nH2O, and the free ligand were screened for antimicrobial activities on some Gram-positive and Gram-negative bacterial species. The free ligand is inactive against all studied bacteria. The screening data showed that [CuLCu] ⋅ H2O > [(H2L)Cu] ⋅ H2O > [CuLZn] ⋅ H2O > [CuLNi] ⋅ 2H2O ≈ [CuLCo] ⋅ H2O in order of biological activity. The data are discussed in terms of their compositions and structures.

Cobalt(II) and Copper(II) Complexes of (2-Acetylpyridine)-(5,6-Diphenyl-[1,2,4]Triazin-3-YL) Hydrazone

A series of cobalt(II) and copper(II) complexes of (2-acetylpyridine)-(5,6-diphenyl-[1,2,4]triazin-3-yl) hydrazone, APyTHy, L, having the formulae [LMCl2]·nH2O, [L2Cu(H2O)2](ClO4)2 and [L2M]X2·nH2O (X = ClO4 or OAc; M = Co or Cu and n = 0, 2 or 4) were isolated and characterized by elemental analysis, molar conductance, magnetic moment and IR, electronic and ESR spectral measurements. The IR spectra indicate that APyTHy behaves as a neutral tridentate ligand, coordinating via a triazine-N, azomethine-N and pyridine-N, except for [LCuCl2] and [L2Cu]X2·nH2O (X = OAc or ClO4), where it acts as a bidentate, not using the triazine-N in complexation. The magnetic moment and electronic spectral data suggest a distorted octahedral structure for 1 : 2 Co(II) complexes, a tetrahedral geometry for 1 : 2 Cu(II) complexes and a trigonal bipyramidal structure for [LCu(H2O)2](ClO4)2 and [LMCl2]·nH2O (M = CoII or CuII; n = 0 or 2) complexes. Upon heating the green [LCuCl2]·2H2O, brown square planar [LCuCl2] was produced. The mixing coefficients and covalency factors for the copper(II) complexes estimated from the combined X-band ESR g-values and electronic d–d transitions using Reinens method imply that the CuN3X2 chromophore is considerably distorted towards square pyramidal.

Cobalt(II) and copper(II) complexes of (2-thiophene)-(5,6-diphenyl-[1,2,4]-triazin-3-yl)hydrazone

New complexes having the formulae [L2CoX2] and [LCuCl2], [LCuCl] and [LCu](ClO4)2 where L = (2-thiophene)-(5,6-diphenyl-[1,2,4]-triazin-3-yl)hydrazone TDPTH; X = Cl, OAc or ClO4 have been synthesized and characterized on the basis of elemental analyses, conductance, magnetic moments and infrared, electronic and ESR spectral data. The IR spectra indicate that TDPTH is a neutral bidentate ligand, coordinating via a triazine-N and azomethine-N in [L2CoX2] and [LCuCl2] with the thiophene-S not coordinated but is tridentate in [LCuCl] and [LCu](ClO4)2 through the same two nitrogen atoms and thiophene-S. The magnetic moment and electronic spectral data suggest a distorted octahedral structure for Co(II) complexes, a dimeric square pyramidal geometry for [LCuCl2] through chloride bridges and a dimeric diamagnetic, four-coordinate copper in [LCu](ClO4)2 through thiophene-S bridges. The X-band ESR spectra of Co(II) complexes, in the solid state, are rhombic with three g values consistent with a high-spin distorted octahedral structure. The X-band ESR spectrum of the powdered sample of both [LCuCl2]·2H2O and [LCu](ClO4)2 at room temperature and at 77 K showed only one broad signal due to ΔM s = ± 1 transition and a weak signal due to the forbidden ΔM s = ± 2 transition, indicating an antiferromagnetic interaction between copper(II) centers whereas [LCuCl] is ESR silent, indicating a monovalent copper ion in this complex.

Synthesis, characterization, potentiometric and thermodynamic studies of transition metal complexes with 1-benzotriazol-1-yl-1-[( p -methoxyphenyl) hydrazono]propan-2-one†

A new series of Mn2+ and Co2+ complexes with 1-benzotriazol-2-yl-1-[(p-methoxyphenyl)-hydrazono]propan-2-one (BMHP) were synthesized and characterized by the elemental analysis, magnetic and different spectral techniques. Proton dissociation constant of the free ligand and the stepwise stability constants of its metal complexes were determined potentiometrically in 0.1 M KC1 and 40% (v/v) ethanol–water. The dissociation constants of the free ligand and its metal complexes were determined at different temperatures and the corresponding thermodynamic parameters were calculated and discussed. The dissociation process was found to be non-spontaneous, endothermic and entropically unfavorable. The changes in the standard ΔG 0 and ΔH 0 accompanying complexation were decreased with increasing metal ionic radius but increased with increasing electronegativity, ionization enthalpy, and hydration enthalpy of the metal ion. The values of (−ΔG 0) and (−ΔH 0) were in the order: Mn2+ < Co2+ < Ni2+ < Cu2+, in accord with the Irving-Williams order. The complexes were found to be stabilized by both enthalpy and entropy changes and the results suggest that complexation is an enthalpy-driven process. The distribution diagrams of the complexes in solution were evaluated. †Presented at the 37th International Conference of Coordination Chemistry (37th ICCC), Cape Town, 13–18 August, 2006.

Synthesis, characterization, and biological activity of N-methyl-2-(1H-1,2,3-benzotriazol-1-y1)-3-oxobutan- ethioamide complexes with some divalent metal (II) ions.

A new series of Zn2+, Cu2+, Ni2+, and Co2+ complexes of N1-methyl-2-(1H-1,2,3-benzotriazol-1-yl)-3-oxobutanethioamide (MBOBT), HL, has been synthesized and characterized by different spectral and magnetic measurements and elemental analysis. IR spectral data indicates that (MBOBT) exists only in the thione form in the solid state while 13C NMR spectrum indicates its existence in thione and thiole tautomeric forms. The IR spectra of all complexes indicate that (MBOBT) acts as a monobasic bidentate ligand coordinating to the metal(II) ions via the keto-oxygen and thiolato-sulphur atoms. The electronic spectral studies showed that (MBOBT) bonded to all metal ions through sulphur and nitrogen atoms based on the positions and intensity of their charge transfer bands. Furthermore, the spectra reflect four coordinate tetrahedral zinc(II), tetragonally distorted copper(II), square planar nickel(II), and cobalt(II) complexes. Thermal decomposition study of the complexes was monitored by TG and DTG analyses under N2 atmosphere. The decomposition course and steps were analyzed and the activation parameters of the nonisothermal decomposition are determined. The isolated metal chelates have been screened for their antimicrobial activities and the findings have been reported and discussed in relation to their structures.

Synthesis and spectroscopic studies of oxovanadium(IV) and dichlorovanadium(IV) complexes of p-X-phenyl-2-picolylketones

A new series of oxovanadium(IV) complexes formulated as [(HL)2VO]n·nSO4 (a), [(HL)VO(SO4)]2 (b), and [L2VO] (c), where HL=phenyl-2-picolylketone and its para-substituted derivatives have been synthesized and characterized. The i.r. data suggest that the ligands are neutral bidentate in classes (a) and (b) and uninegative bidentate in (c), coordinated to the vanadyl ion via the pyridine-N and keto- or enolato-O atoms. Complexes of class (a) showed mechanochromism upon grinding. Magnetic, u.v./vis. and e.s.r. data suggest that all the complexes have a square pyramidal structure with an unpaired electron in the dxy orbital in the solid and in solutions. Deoxygenation of the oxovanadium complexes gave the corresponding dichlorovanadium(IV) derivatives. Elemental analysis, magnetic and spectral studies indicated that the dichlorovanadium(IV) complexes are associated with a distorted trans-octahedral ligand field.

Synthesis, Electrochemical Behavior, Spectral, and Magnetic Studies of Copper(II) Complexes with Ferrocene-Containing Hydrazones

ABSTRACT A new series of copper(II) complexes of the stoichiometry [L2Cu]·nH2O and [(HL)2CuCl2]·2H2O, where HL is 1-acetyl-ferrocene-benzoylhydrazone, 1-acetylferrocene-4-chlorobenzoyl-hydrazone, 1-acetylferrocene-4-hydroxy-benzoylhydrazone or 1-acetylferrocene-4-methylbenzoylhydrazone, HL1, HL2, HL3 or HL4, respectively, were synthesized and characterized. IR data showed that all ligands act as monobasic or neutral bidentates coordinated to copper ion via the oxygen and azomethine N atoms. ESR spectra and magnetic data showed that [(L1)2Cu]·-H2O and [(L3)2Cu]·2H2O are polymeric exhibiting magnetic exchange interaction. ESR data also indicate that all complexes are associated with a d x 2−y 2 ground state. The electrochemical behavior of the free ligands and their copper(II) complexes were studied and are discussed.

Synthesis, characterization, and biological activity studies on (E)-N′-[2-hydroxy-1,2-di(pyridin-2-yl)ethylidine]aroyl hydrazides and their copper(II) complexes

The reaction of copper(II) salts with (E)-N-(2-hydroxy-1,2-di(pyridin-2-yl)ethylidene)aroyl hydrazide (H2L1, H2L2, H3L3) or (E)-N-(2-hydroxy-1,2-di(pyridin-2-yl)ethylidene) isonicotinohydrazide (H2L4) afforded the complexes [(L)Cu(H2O)3], [(H2L)Cu(OAc)(H2O)], [(HL)Cu(OAc)] n , [(H2L)Cu(H2O)](ClO4)2 and [(H2L)Cu(OAc)(H2O)], where n = 1 or 2 and L is the dinegative ion of the ligands. The ligands and their complexes are characterized by elemental analyses, spectral (IR, NMR, electronic, and ESR) and magnetic studies. The FT-IR indicates that the ligands are neutral or anionic polydentate. The number of the coordinating centers depends on the nature of the metal used and the reaction conditions. The room temperature magnetic moment values, electronic spectra and ESR data indicate square planar, trigonal bipyramidal, square pyramidal, and distorted octahedral ligand fields around copper(II). Thermal decomposition of the complexes was monitored by TG and DTG under N2 and the thermal decomposition mechanisms are given. The compounds were screened for their antimicrobial activities on some Gram-positive and Gram-negative bacterial species. The free ligands are inactive against all studied bacteria. The complexes have variable activity with the most active [(H2L)Cu(H2O)](ClO4)2, where H2L is H2L1 or H2L2. The minimum inhibition concentrations for these two complexes were determined. These biological activity results are related to the structures of the compounds.

Synthesis and spectroscopic studies of copper(II) complexes with 1-benzotriazol-1-yl-1-[(p-X-phenyl)hydrazono] propan-2-one

A new series of copper(II) complexes resulted from the reaction of CuCl2·2H2O or Cu(ClO4)2·6H2O and 1-benzotriazol-1-yl-1-[(p-X-phenyl)hydrazono]-propan-2-one, X = H (HL1), Cl (HL2), Br (HL3), OCH3 (HL4) and CH3 (HL5) have been synthesized and characterized by different spectral, magnetic measurements and elemental analysis. IR spectral data indicate that: (i) the free ligands exist in the hydrazo-ketone rather than azo-enol form in the solid state. Furthermore, the hydrazo-NH exists as hydrogen bonded to the keto-oxygen either as intra- or as intermolecular hydrogen bond. (ii) All ligands are neutral bidentate, coordinated to the copper(II) via hydrazone-nitrogen and the keto-oxygen atoms, and (iii) the ionic nature of and coordinated and/or non-coordinated solvent molecules (H2O or EtOH) with the possibility of hydrogen bonding with either the oxo-anions and/or triazole-nitrogen. The magnetic and spectral (UV/Vis and ESR) data indicate that these complexes have square planar, trigonal bipyramidal octahedral and tetrahedral structures. The nature of metal–ligand bonding is determined from the different electronic and ESR spectral parameters. The extent of distortion from ideal symmetry is also estimated and related to the electronic effects of the p-substituents, the nature of the ligand and counter ions.