Synthesis and characterization of new (<Emphasis Type="Italic">E,E</Emphasis>)-dioximes and their divalent metal complexes

Two new soluble vic-dioxime ligands, 4-isopropylanilineglyoxime (L¹H₂) and 4-benzylpiperidineglyoxime (L²H₂) were prepared by reacting 4-isopropylaniline and 4-benzylpiperidine with anti-chloroglyoxime. Ten metal complexes were obtanied by reacting both ligands with Cu(II),Ni(II),Co(II), Zn(II), and Cd(II) cations. The ligands and their metal complexes were elucidated by elemental analysis, IR, UV-vis, ¹H NMR, and ¹³C NMR and also magnetic moments of the complexes were determined. The text was submitted by the authors in English.     

The synthesis and characterization of some new vic-dioximes and their transition metal complexes

In this study, three new vic-dioximes, [L¹H₂], N-(5-chloro-2-methoxyphenyl)amino-1-acetyl-1-yclohexenylglyoxime, [L²H₂],N-(3-chloro-4-methoxyphenyl)amino-1-acetyl-1-cyclohexenylgly-oxime and [L³H₂], N-(3-chloro-2-methoxyphenyl)amino-1-acetyl-1-cyclohexenylglyoxime were synthesized from 1-acetyl-1-cyclohexeneglyoxime and the corresponding substituted aromatic amines. Metal complexes of these ligands were also synthesized with Ni(II), Cu(II) and Co(II) salts. The structures of these new compounds (ligands and complexes) were characterized with FT-IR, magnetic susceptibility measurement, molar conductivity measurements, mass spectrophotometer measurements, thermal methods (TGA), ¹H NMR and ¹³C NMR spectral data and elemental analyses.     

The synthesis and characterization of three new vic -dioximes and their nickel(II), copper(II) and cobalt(II) complexes

Three new vic-dioximes, [L¹H₂], N-(4-ethylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, [L²H₂], N-(4-butylphenyl)amino-1-acetyl-1-cyclohexenylglyoxime, and [L³H₂], N-(4-methoxyphenyl)amino-1-acetyl-1-cyclohexenylglyoxime were synthesized from 1-acetyl-1-cyclohexeneglyoxime and the corresponding substituted aromatic amines. Metal complexes of these ligands were also synthesized with Ni(II), Cu(II), and Co(II) salts. These new compounds (ligands and complexes) were characterized with FT–IR, magnetic susceptibility measurement, molar conductivity measurements, mass spectrometry measurements, thermal methods (e.g. thermal gravimetric analysis), ¹H NMR (Nuclear Magnetic Resonance) and ¹³C NMR spectral data and elemental analyses.     

Synthesis and characterization of substituted aminobiphenylglyoximes and their complexes with some transition metals

In this study, four different new vic-dioximates, [L¹H₂] N-(4-ethylphenyl)amino-biphenylglyoxime, [L²H₂] N-(4-butylphenyl)aminobiphenylglyoxime, [L³H₂] N-(4-aminoacetanilide)aminobiphenylglyoxime, and [L⁴H₂] N-(thiazol-2-yl-aminobiphenylglyoxime are synthesized from anti-4′-biphenylchloroglyoxime and the corresponding substituted aromatic amines. The Co(II), Ni(II), and Cu(II) complexes of these ligands are prepared. The structures of these new ligands and their complexes are proposed based upon IR, ¹H, and ¹³C NMR spectral data, mass spectroscopy, magnetic susceptibility measurement, and elemental analyses. The text was submitted by the authors in English.     

Synthesis of (2-hydroxo-5-chlorophenylaminoisonitrosoacetyl)phenyl ligands and their complexes: Spectral,thermal and solvent-extraction studies

Four different types of new ligands Ar[COC(NOH)R] _n (Ar=biphenyl, n = 1 H₂L¹; Ar=biphenyl, n = 2 H₄L²; Ar=diphenylmethane, n = 1 H₂L³; Ar=diphenylmethane, n = 2 H₄L⁴; R=2-amino-4-chlorophenol in all ligands) have been obtained from 1 equivalent of chloroketooximes Ar[COC(NOH)Cl] _n (HL¹-H₂L⁴) and 1 equivalent of 2-amino-4-chlorophenol (for H₂L¹ and H₂L³) or 2 equivalent of 2-amino-4-chlorophenol (for H₄L² and H₄L⁴). (Mononuclear or binuclear cobalt(II), nickel(II), copper(II) and zinc(II) complexes were synthesized with these ligands.) These compounds have been characterized by elemental analyses, AAS, infra-red spectra and magnetic susceptibility measurements. The ligands have been further characterized by ¹H NMR. The results suggest that the dinuclear complexes of H₂L¹ and H₂L³ have a metal:ligand ratio of 1:2; the mononuclear complexes of H₄L² and H₄L⁴ have a metal:ligand ratio of 1:1 and dinuclear complexes H₄L² and H₄L⁴ have a metal:ligand ratio of 2:1. The binding properties of the ligands towards selected transition metal ions (Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Pb^II, Cd^II, Hg^II) have been established by extraction experiments. The ligands show strong binding ability towards mercury(II) ion. In addition, the thermal decomposition of some complexes is studied in nitrogen atmosphere.     

Synthesis,spectral studies,and antimicrobial activity of binary and ternary Cu(II), Ni(II), and Fe(III) complexes of new hexadentate Schiff bases derived from 4,6-diacetylresorcinol and amino acids

Two new hexadentate N₂O₄ donor Schiff bases, H₄L¹ and H₄L², were synthesized by condensation of 4,6-diacetylresorcinol with glycine and alanine, respectively. The structures of the ligands were elucidated by elemental analyses, IR, ¹H NMR, electronic, and mass spectra. Reactions of the Schiff bases with copper(II), nickel(II), and iron(III) nitrates in 1 : 2 molar ratio gave binuclear metal complexes and, in the presence of 8-hydroxyquinoline (8-HQ) or 1,10-phenanthroline (Phen) as secondary ligands (L′), mixed-ligand complexes in two molar ratios 1 : 2 : 2 and 1 : 2 : 1 (L¹/L² : M : L′). The complexes were characterized by elemental and thermal analyses, IR, electronic, mass, and ESR spectral studies, as well as conductivity and magnetic susceptibility measurements. The spectroscopic data reveal that the Schiff-base ligands were dibasic or tetrabasic hexadentate ligands. The coordination sites with the metal ions are two azomethine nitrogens, two oxygens of phenolic groups, and two oxygens of carboxylic groups. Copper(II) complexes were octahedral and square planar while nickel(II) and iron(III) complexes were octahedral. The Schiff bases, H₄L¹ and H₄L², and some of their metal complexes showed antibacterial activity towards Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Pseudomonas fluorescens and Pseudomonas phaseolicola) bacteria and antifungal activity towards the fungi Fusarium oxysporium and Aspergillus fumigatus.     

Redox, thermodynamic and spectroscopic of some transition metal complexes containing heterocyclic Schiff base ligands

Complexes of two series of Schiff base ligands, H₂L_a and H₂L_bderived from the reaction of 2,6-diacetyl pyridine with semicarbazide, H₂L_a and thiosemicarbazide, H₂L_b, with the metal ions, Co(II), Ni(II), Cu(II), VO(IV) and UO₂(VI) have been prepared. The ligands are characterized by elemental analysis, IR, UV–vis and ¹H NMR. The structures of the complexes are investigated with the IR, UV–vis, X-band ESR spectra, ¹H NMR and thermal gravimetric analysis as well as conductivity and magnetic moment measurements. The IR-spectra reveal the presence of variable modes of chelation for the investigated ligands. A variety of binuclear or mononuclear complexes were obtained with the two ligands in tri-, tetra or pentadentate forms. The bonding sites are the pyridine nitrogen, two azomethine nitrogen atoms and ketonic oxygen in case of H₂L_a or sulphur atoms in case of H₂L_b. The Coats–Redfern equation has been used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. Cyclic voltammograms of Co(II) and Ni(II) show quasi-reversible peaks. The redox properties and the nature of the electro-active species of the complexes have been characterized.     

Synthesis,spectroscopic and electrochemical studies of copper(II) and cobalt(II) complexes of three unsymmetrical vic -dioximes ligands

Cobalt(II) and copper(II) complexes with three dioxime ligands cyclohexylamine-p-tolylglyoxime (L₁H₂), tert-butyl amine-p-tolylglioxime (L₂H₂) and sec-butylamine-p-tolylglyoxime (L₃H₂), have been prepared. The metal to ligand ratios of the complexes were found to be 1?:?2. The Cu(II) complexes of these ligands are proposed to be square planar; the Co(II) complexes are proposed to be octahedral with water molecules as axial ligands. Ligands and complexes are soluble in common solvents such as DMSO, DMF, CHCl₃ and C₂H₅OH. The ligands have been characterized by elemental analysis, IR, UV-VIS, ¹H?NMR, ¹³C?NMR and thermogravimetric analysis (TGA). The complexes were characterized by elemental analysis, IR, UV-VIS, magnetic susceptibility measurements, thermogravimetric analysis (TGA) and electrochemistry. Electrochemical properties of metal complexes show quasi-reversible one-electron redox processes. However, Co(L₁H)₂ and Cu(L₁H)₂ complexes show another oxidation peak in the positive region. This single irreversible oxidation peak is caused by the cyclic ring of the ligand. Data also revealed that the electron transfer rates of metal complexes with L₁H₂ are higher than the other complexes.     

Synthesis and spectroscopic studies of new binuclear transition metal complexes of Schiff bases derived from 4,6-diacetylresorcinol

Two new series of copper(II), nickel(II), cobalt(II), zinc(II), iron(III), chromium(III), vanadyl(IV) and uranyl(VI) complexes with two bifunctional tridentate Schiff base, H₄L¹ and H₂L² ligands have been prepared. The Schiff base, H₄L¹ and H₂L², ligands were synthesized by the condensation of 4,6-diacetylresorcinol with o-aminophenol or o-phenylenediamine. The ligands are either di- or tetra-basic with two symmetrical sets of either OON or NNO tridentate chelating sites. The ligands and their metal complexes have been characterized by elemental analysis, ¹H-n.m.r., FT-IR, mass, electronic, esr spectra and thermal gravimetric analysis and magnetic susceptibility. With the exception of Co^II ion with H₂L² which afforded a trinuclear complex, a variety of binuclear complexes for the rest of the metal complexes were obtained with the ligands in its di- or tetra-deprotonated forms. The bonding sites are the azomethine and amino nitrogen atoms, and phenolic oxygen atoms. The metal complexes exhibit different geometrical arrangements such as square planar, tetrahedral, square pyramid and octahedral arrangement.     

Synthesis of Substituted 4,4′-Oxy-bis(aminophenylglyoximes) and Their Polymeric Metal Complexes with Cu(II), Ni(II), and Co(II) Salts

4,4′-Bis(chloroacetyl)diphenyl ether (HL) was synthesized from chloroacetyl chloride and diphenyl ether in the presence of AlCl₃ as catalyst by Friedel-Crafts reaction. Subsequently, its keto oxime (H₂L) and glyoxime (H₄L) derivatives were also prepared. Then, five new substituted 4,4′-oxy-bis(aminophenyl-glyoximes) (H₄L_1–5) were synthesized from 4,4′-oxy-bis(chlorophenylglyoxime) and the corresponding amines. The Ni(II), Cu(II), and Co(II) complexes of these ligands were prepared. The structures of these ligands and their complexes were identified by FT-IR, ¹H NMR, and ICP-AES spectral data, elemental analyses, and magnetic measurements.     

Synthesis and spectral studies of new N2S2 and N2O2 Mannich base ligands and their metal complexes

New Mannich bases bis(thiosemicarbazide methyl) phosphinic acid H₃L¹ and bis(1-phenylsemicarbazide methyl) phosphinic acid H₃L² were synthesized from condensation of phosphinic acid and formaldehyde with thiosemicarbazide and 1-phenylsemicarbazide, respectively. Monomeric complexes of these ligands, of general formula K₂[Cr^III(L ⁿ )Cl₂], K₃[Fe^II(L¹)Cl₂], K₃[Mn^II(L²)Cl₂], and K[M(L ⁿ )] (M = Co(II), Ni(II), Cu(II), Zn(II) or Cd(II); n = 1, 2) are reported. The mode of bonding and overall geometry of the complexes were determined through IR, UV-Vis, NMR, and mass spectral studies, magnetic moment measurements, elemental analysis, metal content, and conductance. These studies revealed octahedral geometries for the Cr(III), Mn(II), and Fe(II) complexes, square planar for Co(II), Ni(II), and Cu(II) complexes and tetrahedral for the Zn(II) and Cd(II) complexes. Complex formation via molar ratio in DMF solution has been investigated and results were consistent to those found in the solid complexes with a ratio of (M : L) as (1 : 1).     

Heteronuclear complexes of oxorhenium(V) with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) and their biological activities

Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO₂(VI) ions were prepared by the reaction of the complex ligands [ReO(HL¹)(PPh₃)(OH₂)Cl]Cl (a) and/or [ReO(H₂L²)(PPh₃)(OH₂)Cl]Cl (b), where H₂L¹?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H₃L²?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1?:?1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO₂(VI) and Cu(II) using 2?:?1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N⁷ group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO₂(VI)?complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and ¹H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics.     

Synthesis,structure, and characterization of picolyl- and benzyl-linked biphenyl palladium N-heterocyclic carbene complexes and their catalytic activity in acylative cross-coupling reactions

N-heterocyclic carbene ligands with picolyl (L¹H₂Br₂, L³H₂Br₂) and benzyl (L²H₂Br₂, L⁴H₂Br₂) linked biphenyl backbone were synthesized and characterized. Their palladium(II) complexes [PdL¹]Br₂ ( 1 ), [PdL²Br₂] ( 2 ), [PdL³]Br₂ ( 3 ), and [PdL⁴Br₂] ( 4 ) were synthesized by direct method using Pd(OAc)₂. All complexes ( 1 – 4 ) were characterized by CHN analysis, electrospray ionization-MS, nuclear magnetic resonance, and single-crystal X-ray diffraction. Molecular structures confirm the distorted square planar geometry around the Pd(II) center. All of them showed good catalytic activity in acylative Suzuki cross coupling of phenyl boronic acid with benzoyl chloride to afford benzophenone in good yields.     

Synthesis,characterization, and biological properties of Ni(II), Co(II), and Cu(II) complexes of Schiff bases derived from 4-aminobenzylamine

New Schiff bases, N,N′-bis(salicylidene)-4-aminobenzylamine (H₂L¹), N,N′-bis(3-methoxysalicylidene)-4-aminobenzylamine (H₂L²), and N,N′-bis(4-hydroxysalicylidene)-4-aminobenzylamine (H₂L³), with their nickel(II), cobalt(II), and copper(II) complexes have been synthesized and characterized by elemental analyses, electronic absorption, FT-IR, magnetic susceptibility, and conductance measurements. For the ligands, ¹H and ¹³C NMR and mass spectra were obtained. The tetradentate ligands coordinate to the metal ions through the phenolic oxygen and azomethine nitrogens. The keto-enol tautomeric forms of the Schiff bases H₂L¹, H₂L², and H₂L³ have been investigated in polar and apolar solvents. All compounds were non-electrolytes in DMSO (～10^?3 M) according to the conductance measurements. Antimicrobial activities of the Schiff bases and their complexes have been tested against Acinobacter baumannii, Pseudomonas aeruginosa, Micrococcus luteus, Bacillus megaterium, Corynebacterium xerosis, Staphylococcus aureus, Escherichia coli, Candida albicans, Rhodotorula rubra, and Kluyveromyces marxianus by the disc diffusion method; biological activity increases on complexation.     

Spectral characterization and biological evaluation of Schiff bases and their mixed ligand metal complexes derived from 4,6-diacetylresorcinol

In the present study two new series of Copper(II), Nickel(II) and Cobalt(II) complexes with two newly synthesized Schiff base ligands 4,6-bis(1-(4-bromophenylimino)ethyl)benzene-1,3-diol (H₂L¹), 4,6-bis(1-(4-methoxyphenylimino) ethyl)benzene-1,3-diol (H₂L²) and organic ligands 8-hydroxy quinoline, 1,10-phenanthroline have been prepared. The Schiff bases H₂L¹ and H₂L² ligands were synthesized by the condensation of 4,6-diacetyl resorcinol with 4-bromo aniline and 4-methoxy aniline. The ligands and their metal complexes have been characterized by FT-IR, Mass, ¹H NMR, UV–Vis., elemental analysis, ESR and Thermal gravimetric analysis. The Schiff base and their metal complexes were tested for antimicrobial activity against gram positive bacteria Staphylococcus aureus, Streptococcus pyogenes and gram negative bacteria Escherichia coli, Pseudomonas aeruginosa and fungus Candida albicans, Aspergillus niger and Aspergillus clavatus using Broth Dilution Method.     

Synthesis,characterization, and biological investigation of new mixed-ligand complexes

A novel series of mixed-ligand complexes of 5,5′-{(1E,1E′)-1,4-phenelynebis(diazene-2,1-diyl)}bis(quinolin-8-ol) (H₂L₁) as a primary ligand and 4-aminoantipyrine(L₂) as a secondary ligand with Mn(II) ion were prepared using two general formulae: [Mn₂(H₂L₁)₂(L₂)₂X₄].4Cl (X = OH₂( 1 ), ONO₂⁻( 2 ), Cl=nil; OAc( 3 ), Cl = nil) and [Mn₂(H₂L₁)(L₂)₂(O₂SO₂)₂]( 4 ). Free ligands and their complexes were characterized. Electronic absorption spectra of the mixed-ligand complexes indicate a distorted octahedral geometry around the central metal ion, and the anions X⁻ are in the axial positions for all compounds. The ligands behave in a neutral bidentate manner, through nitrogen atoms and oxygen atoms of the carbonyl group (L₂), whereas H₂L₁ coordinated through nitrogen and OH groups as a neutral bidentate ligand. All complexes do not contain coordinated water molecules, but complex ( 1 ) contains four water molecules. The water molecules are removed in a single step. The complexes exhibited magnetic susceptibility corresponding to five unpaired electrons. The antimicrobial activity of the Mn(II) mixed-ligand complexes ( 1–4 ) against two gram-positive bacteria, three local gram-negative bacteria, and three fungi species was tested. Mn(II) mixed-ligand complex ( 2 ) exhibited significant antibacterial activity against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas sp. Mixed-ligand complex ( 2 ) exhibited a high potential cytotoxicity against the growth of human lung cancer cells.     

Coordination chemistry of some new Cu(II), Ni(II) and Co(II) macroacyclic (N2O4) Schiff base complexes: X-ray crystal structure of Cu(II) complex

Six new Cu(II), Ni(II) and Co(II) macroacyclic Schiff base complexes [M^II(H₂L)](ClO₄)₂ (L = L¹ and L²) (I–VI) were prepared by the reaction of two new N₂O₄ Schiff base ligands in equemolar ratios. The ligands H₂L¹ and H₂L² were synthesized by reaction of 2-[2-(2-formyl phenoxy)ethoxy]benzaldehyde (A¹) and/or 2-[2-(3-formylphenoxy)propoxy]benzaldehyde (A²) and ethanol amine and characterized with IR and ¹H, ¹³C NMR spectroscopy. All complexes were characterized by microanalysis, IR and mass spectrometry, whereas complex I was also characterized by single crystal X-ray (CIF file CCDC no. 1020055). The X-ray structure of complex I revealed that all nitrogen and oxygen atoms of ligand (N₂O₄) have coordinated to the metal ion. However, Cu²⁺ ion is in six coordination environment that can bedescribed as a distorted octahedral geometry.     

Synthesis and spectral characterization of some binuclear complexes designed from N4O and N2O3 donor Schiff-base ligands of 2,6-diformyl-4-methylphenol

New pentadentate binucleating ligands containing phenoxide as an endogenous bridging group, 2,6-diformyl-4-methylphenol bis(carbohydrazone) (L¹H), and 2,6-diformyl-4-methylphenol bis(semicarbazone) (L²H), and their binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes of general formula [M₂LCl₃] · nH₂O with chloride as an exogenous bridge have been synthesized. The complexes were characterized on the basis of elemental analysis, conductivity measurements, thermal analysis, IR, Far-IR, NMR, UV–Vis, EPR, FAB-mass and magnetic data. The coordination mode (N₄O, N₂O₃), as well as endogenous phenoxide bridge and an exogenous chloride bridge have been established on the basis of IR, Far-IR and ¹H-NMR spectral data. Electronic spectral data of the complexes indicate square-pyramidal geometry. EPR spectra show line broadening, which is further supported by weak antiferromagnetic interaction from the room temperature magnetic moment data. All compounds show appreciable antimicrobial activity.     

The synthesis of two new isonitrosoacetophenone derivatives and investigation of their Ni(II), Co(II), Cu(II), and Zr(IV) complexes

In the present study, two new ligands, 4-chlorobenzal-azino-isonitrosoacetophenone (L₁), 4-methylbenzal-azino-isonitrosoacetophenone (L₂) and their metal complexes were synthesized using acetophenone as a starting material. The coloured complexes were prepared by the addition of chloride salts of Ni(II), Co(II), Cu(II) and Zr(IV) ions to a solution of ligands. In conclusion, the structures of the obtained ligands and their complexes were characterized by FT-IR, and ¹H NMR spectra, AAS (atomic absorption spectrum) analysis, magnetic susceptibilities as well as elemental analysis.     

Synthesis and crystal structure of some new cadmium (II) macrocyclic Schiff-base complexes containing piperazine moiety

The metal templated Cd(II) cyclocondensation of 2,6-diacetylpiridine or 2,6-pyridinedicarbaldehyde and two different amines containing piperazine moieties have been investigated. The resulting ligands, L¹ and L² are 16- and L³ and L⁴ 17-membered pentaaza macrocycles. The complexes have been characterized by a variety of methods including IR, ¹H, ¹³C NMR, DEPT, COSY(H,H), HMQC(H,C), FAB spectrometry and conductivimetry measurements. The crystal structures of [CdL²Cl](CH₃OH)ClO₄ (2) and [CdL⁴(NO₃)(H₂O)]ClO₄ (4) have been also determined, and it was shown that the geometry of the Cd(II) ion in the complexes is slightly distorted pentagonal pyramidal and pentagonal bipyramidal, respectively. The gas-phase structures of ligands, L² and L⁴ and their Cd(II) complexes have also theoretically studied.