Series Of Novel Metal Complexes Research Articles

Synthesis, characterization and biological activity of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes derived from Schiff base ligand quinoxaline-2-carboxaldehyde and 4-aminoantipyrine

A series of novel metal complexes of 4-aminoantipyrine quinoxaline (4-AAPQ) Schiff base derived from 4-aminoantipyrine and quinoxaline-2-carboxaldehyde were synthesized. The structural and properties of these compounds were characterized by spectral methods (IR, mass, 1H NMR, 13C NMR, UV–Vis), molar conductance, and elemental analysis. The binding stoichiometry mode was confirmed as 1:1 (metal: ligand) by analytical, and spectral data. The type of coordination of the metal to azomethine nitrogen and quinoxaline nitrogen atoms of the ligand were determined by spectral data. In this case, the ligand acts as a bidentate donor with the coordination number of four in prepared complexes. The synthesized compounds were tested for two types of cancer cell lines consisting of human colon cancer (HT-29) and breast cancer (MCF-7), as well as one normal cell line containing human foreskin fibroblast (HFF) using MTT cell viability assay. A comparative study of the IC50 values indicates that 4-AAPQ-Cu (II)/ and Mn(II) complexes exhibit higher activity than related Schiff base ligand on the MCF-7 cell line. Also, 4-AAPQ-Mn(II)/ and -Zn(II) complexes were the most active compounds with the highest inhibition against HT-29 cell line after 48 h. Molecular docking studies of 4-AAPQ Cu(II) within the c-kit active site as a validated target displayed 344.33 nM and -8.82 kcal/mol for inhibition constant (Ki) and free energy of binding, respectively.

Synthesis, Spectral Identification, Antibacterial Evaluationand Theoretical Study of Co, Fe, Rh and Pd Complexes for 2-benzoylthiobenzimidazol

A new novel series of metalcomplexes are prepared from reactions between 2-benzoylthio- benzimidazole (L) with metal salts of Co (II) , Fe(III) and Rh (III) , while Pd(II) complex was obtained by mixing ligandsof 2-benzoylthiobenzimidazole (L) as primary ligand and bipyridine (L/)as secondary ligand as well as palladium chloride as metal salt in an ethanoic medium. The geometry of these compounds were identified using C.H.N.microanalysis, Ultraviolet–visible, Fourier transforms infrared, magnetic susceptibility, molar conductivity and flame atomic absorption (A.A). From the dataobtained by these spectral analyses, the molecular structures for Rh and Fe complexes were proposed to be octahedral geometry. A square planar construction is proposed for Pd(II), while a Tetrahedral Geometry for Cobalt (II)complex. All of the complexes which were prepared displayedobviousconstancy and could be stored for months without showing any considerablealteration. Semi-empirical methods (ZINDO/1, ZINDO/S & PM3) were conducted to assess the heat of formation ∆H˚f, binding energy ∆Eb, and dipole moment for all compounds as theoretic study. The complexes expressnotable biological activities to pathogenic bacteria when inspected on certain bacteria. The synthesized compounds exhibited moderate toverygood antibacterial activity against bacterial strains, i.e., Escherichiacoli, Staphylococcus aureus & Pseudomonas aeruginosa.

Syntheses and structure of dinuclear metal complexes containing naphthyl-Ir bichromophore.

A series of novel metal complexes were synthesized containing an Ir-cyclometalated bichromophore as a visible-light sensitizer. A new bichromophoric unit containing a naphthyl substituent and methyl substituents on the 2-phenylpyridine chelating ligand was synthesized and characterized for the first time. According to the increased crystallinity of the bichromophoric unit, novel Ir-M metal complexes (M = Pd, Mn, and Ir) were synthesized and fully characterized. The novel Ir-Pd complex maintained photocatalytic activity toward styrenes under visible-light irradiation, and polymerization with p-chlorostyrene, copolymerization with styrene and p-chlorostyrene furnished corresponding polymers.

Novel Cu(II), Ni(II), Zn(II), Cd(II), and Mg(II) complexes with a series of 2-arylhydrazono-1,3-dicarbonyl compounds. Synthesis, structure and spectroscopic characteristics

A series of novel metal complexes of Cu(II), Ni(II), Zn(II), Cd(II), and Mg(II) with four N-heterocyclic derivatives of 2-arylhydrazono-1,3-dicarbonyl compounds were isolated and identified by FT IR, 1H NMR, EPR, and UV–Vis spectroscopy. The crystallographic data for two organic ligands as well as Mg(II) and Ni(II) complexes were obtained. It was indicated that the organic species exist in the form of hydrazo-tautomers. The Ni complex is monomeric and is characterized by the tridentate coordination of the ligand through a deprotonated N-atom of the hydrazo-fragment and two neighboring O-atoms of the carbonyl and deprotonated hydroxy-groups. In the case of the Mg complex the polymeric structure is observed with the additional coordination through the sulfamide group of the organic specie. Formation constants of the complexes in ethanol aqueous solutions were calculated and correlated with some physical characteristics of the metal cations. Structures of yet unstudied metal complexes were proposed based on quantum-chemical modeling at the DFT/B3LYP level.

Synthesis, characterisation, thermal properties and biological activity of coordination compounds of novel selenosemicarbazone ligands

A series of novel metal complexes with bidentate selenosemicarbazone Schiff-base ligands HL1 and HL2 are reported. The reaction of 2-(((3-nitrophenyl)amino)(phenyl) methyl)cyclohexan-1-one and 2-((4-methoxyphenyl)(phenylamino)methyl)cyclohexan-1-one with an ethanolic mixture of KSeCN and NH2NH2 afforded the preparation of the novel selenosemicarbazone ligands (E)-2-(2-(((3-nitrophenyl) amino)(phenyl)methyl)cyclohexylidene)hydrazine-1-carboselenoamide (HL1) and (E)-2-(2-((4-methoxyphenyl)(phenylamino)methyl)cyclohexylidene)hydrazine-1-carboselenoamide (HL2), respectively. The reaction of ligands with Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal ions resulted in the formation of mononucleating complexes of general formula K2[ML2Cl2] and [M’L2], (M = Mn(II), Co(II) and Ni(II); M’ = Cu(II), Zn(II) and Cd(II)). The mode of bonding and predicted geometry of complexes were determined through their physico-chemical and spectroscopic measurements. These data indicated the formation of the following; (i) a distorted octahedral geometry about Mn(II), Co(II) and Ni(II), (ii) a distorted square planar around Cu(II), and (iii) a tetrahedral arrangement about Zn(II) and Cd(II) ions. The thermal properties and biological activity of ligands and their metal complexes were studied. The title ligands and their metal complexes were screened against Gram negative bacterial strains; Escherichia coli (E. coli), Bacillus sabtuius and Klebsiella pneumoniae and Gram positive bacterial strain Staphylococcus aureus that revealed the metal complexes become more potentially resistive to the microbial activities, compared to the free ligands. Further, selenosemicarbazone ligands and their complexes were examined for their antifungul activity towards Candida albicans, Candida glabrata, Candida tropicalis and Candida parapsilsis, which generally showed complexes are more active compared to the free ligands.

Synthesis, Characterization and Biological Activity of Novel Zirconium, Zinc and Cadmium Complexes Derived from Substituted Tetramethyl Guanidine

A novel series of metal complexes of guanidine ligand derived from condensation of 1,1,3,3-tetramethylurea and 2-aminopyridine in present of POCl3 have been synthesized. The complexes are characterized using FTIR, UV-Vis and also molar conductance was measured. These spectroscopic studies confirmed that the ligand bonded to the metals through the nitrogen atoms. The suggested structures of the metal complexes are square planner. The ligand and its metal complexes were tested against Gram-negative bacteria; Escherichia coli, Serratia marcescens and Gram-positive bacteria; Bacillus sabtilis and Staphylococcus aureus by applying disc diffusion method. The most antibacterial activity of synthesized compounds belongs to CdL2 complex. The results of this study showed that the metal complexes have more antibacterial activity against species when compared to the parent ligand.

Synthesis and characterization of a series of novel metal complexes of N-heterocyclic azo-colorants derived from 4-azo-pyrazol-5-one

A series of novel metal complexes of Cu(II), Co(II), Ni(II), and Zn(II) with three N-heterocyclic derivatives of 4-azo-pyrazol-5-one were isolated and identified by FT IR, 1H NMR, ESR, and UV–Vis spectroscopy. The crystallographic data for a sodium salt as well as Co(II) and Cu(II) complexes were obtained. Formation constants of the complexes in ethanol aqueous solutions were calculated. Structures of yet unstudied metal complexes were proposed based on quantum-chemical modeling at the DFT/B3LYP level.

SYNTHESIS AND EVALUATION OF ANTI-INFLAMMATORY AND ANALGESIC ACTIVITIES OF SOME NEWLY SYNTHESIZED METAL COMPLEXES OF COUMARIN SCHIFF BASES

A novel series of metal complexes of coumarin Schiff bases have been synthesized by reacting to coumarin Schiff bases with cobalt (II) nitrate and zinc chloride. The IR, 1H and NMR spectral data were obtained to characterize the structures of newly synthesized compounds. Newly synthesized compounds were evaluated for acute anti-inflammatory activity using carrageenan-induced rat paw edema and analgesic activity by acetic acid induced writhing method. In acute anti-inflammatory activity, the rat paw volume was measured before and after 0.5, 1,3 and 6 h of the carrageenan injection. Compounds IIIajwere administered at a dose of 10mg/kg body weight, 0.5h before the carrageenan injection. The results showed 36.69, 45.87 and 31.19% inhibition of edematous volume at third hour against carrageenan induced paw edema.The compounds IIIa, IIIbandIIIcwere screened for analgesic activity and measured by noting the writhing response by acetic acid in mice gave 43.01, 34.05 and 26.24% of protection against acetic acid induced writhing, respectively. These results confirm the encouraging anti-inflammatory and analgesic activity of the metal complexes of coumarins Schiff bases.

Geometrical structures, thermal properties and antimicrobial activity studies of azodye complexes

A novel series of metal complexes with 4-(2,3-dimethyl-1-phenylpyrazol-5-one azo)-3-aminophenol ligand (HL) are prepared and characterized by elemental analyses, IR, UV–Visible spectra, 1H NMR spectra, mass spectra, X-ray diffraction analysis, conductivity measurements and magnetic susceptibility measurements as well as thermal analysis. The IR spectrum revealed that the ligand (HL) coordinates as monobasic tridentate manner with ONO donor sites of nitrogen atom of azo group (NN), oxygen atom of the deprotonated phenolic OH group and exocyclic carbonyl oxygen atom forming a five/six-membered chelate structures. The 1H NMR spectra data indicated that the phenolic proton is also displaced during complexation. From the magnetic and spectral studies, it was obvious that the geometrical structures of these complexes are octahedral. The molecular structures of the ligand (HL) and its metal complexes are optimized theoretically and the quantum chemical parameters are calculated. The XRD patterns of the ligand (HL) and complex (3) are a mixture of crystalline and amorphous phases. The activation thermodynamic parameters, such as activation energy (Ea), enthalpy (ΔH⁎), entropy (ΔS⁎), and Gibbs free energy change of the decomposition (ΔG⁎) are calculated using Coats–Redfern and Horowitz–Metzger methods. The ligand (HL) and its metal complexes are screened for their antimicrobial activity against, four bacteria (two Gram positive, i.e. Bacillus subtilis, Streptococcus pneumoniae, and two Gram negative, i.e. Escherichia coli and Pseudomonas aeruginosa) and two fungi species (Aspergillus fumigatus and Candida albicans). The obtained data implies that all the complexes have high antimicrobial activities toward B. subtilis, S. pneumoniae, E. coli and A. fumigatus than the ligand (HL). In addition to that, complexes (1), (3) and (5) showed antifungal effect against C. albicans.

Synthesis and characterization of some metal complexes derived from azo compound of 4,4′-methylenedianiline and antipyrine: Evaluation of their biological activity on some land snail species

A novel series of metal complexes of the azo dye; bis-(1,5-dimethyl-4-[(E)-(3-methylphenyl)diazenyl]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one) derived from 4,4′-methylenedianiline and antipyrine was synthesized and characterized by different spectral, thermal and analytical methods. The tetradentate ligand reacts with the metal ions as a half unit. All complexes display an octahedral geometry, except Pd(II) complex (7) which has a square planar one. The thermal studies reveal that the complexes have higher thermal stability comparable with that of the free ligand. The activation thermodynamic parameters, such as activation energy (E*), enthalpy of activation (ΔH*), entropy of activation (ΔS*) and Gibbs free energy (ΔG*) have been calculated using DTG curves. The ESR spectra of the solid Cu(II) complexes showed an axial symmetry with 2B1g as a ground state and hyperfine structure. The biological activities of the ligand, as well as its metal complexes have been tested in vitro against two land snail species; Eobania vermiculata and Monacha obstructa. The results show that all the tested compounds have significant biological activities against the two tested land snail species with different sensitivity levels.

Crystal structure, optical properties and electrochemiluminescence of Cu(I), Ag(I) and Au(I) complexes that contain the cyanoacetic acid triphenylamine ligand

A series of novel metal complexes, [Cu2(dppm)2(OOCL)]2[NO3]2 (1), [Ag2(dppm)2(OOCL)2] (2) and [Au2(dppm)2(OOCL)2] (3) (dppm=bis(diphenylphosphino)methane, L=2-cyano-3-(4-(diphenylamino) phenyl)acrylic acid) were prepared and structurally characterized by X-ray crystallography. Their optical properties were investigated by absorption and fluorescence spectra. The fluorescence spectra of the complexes showed red shifts relative to that of L, which exhibited the same tendency as the absorption spectra. In addition, the ability of 1–3 to generate electrochemiluminescence (ECL) were assessed in acetonitrile solutions, they exhibited a highly enhanced stable ECL emission compared to the free ligand (L). Especially, the ECL intensity of 1 was approximately 30 times greater than that of L.

Pharmacologically significant complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) of novel Schiff base ligand, (E)-N-(furan-2-yl methylene) quinolin-8-amine: Synthesis, spectral, XRD, SEM, antimicrobial, antioxidant and in vitro cytotoxic studies

A novel series of metal complexes of the types, [ML2(H2O)2]Cl2 and [ML2]Cl2 [M=Mn(II), 1; Co(II), 2; Ni(II), 3; Cu(II), 4; and Zn(II), 5] were synthesized by the interaction of ligand, L (E)-N-(furan-2-yl methylene) quinolin-8-amine, derived from the condensation of 2-furaldehyde and 8-aminoquinoline. The synthesized ligand and its metal complexes were characterized on the basis of results obtained from elemental analysis, ESI-MS, XRD, SEM, TGA/DTA, FT-IR, UV-Vis, magnetic moment and 1H and 13C NMR spectroscopic studies. EPR parameters were recorded in case of complex 4. The comparative in-vitro antimicrobial activities against various pathogens with reference to known antibiotics and antioxidant activity against standard control at variable concentrations revealed that the metal complexes show enhanced antimicrobial and free radical scavenging activities in general as compared to free ligand. However, the complexes 1 and 5 have shown best antioxidant activity among all the metal complexes. Furthermore, comparative in-vitro antiproliferative activity on ligand and its metal chelates performed on MDA-MB-231 (breast carcinoma), KCL22 (blood lymphoid carcinoma), HeLa (cervical carcinoma) cell lines and normal cells (PBMC) revealed that metal chelates show moderate to good activity as compared to ligand where as complex 1 seems to be the most promising one possessing a broad spectrum of activity against all the selected cancer cell lines with IC50<2.10μM.

Novel metal complexes of naphthalimide–cyclam conjugates as potential multi-target receptor tyrosine kinase (RTK) inhibitors: Synthesis and biological evaluation

A novel series of metal complexes of naphthalimide–cyclam conjugates were synthesized and their in vitro antitumor activities were evaluated. The newly-synthesized compounds showed huge diversity of antiproliferative potency due to variety of metal ions and length of alkyl chains, among which the Zn(II) and Cr(III) complexes exhibited comparable antiproliferative activities with amonafide via multiple tyrosine kinase inhibition. Further research revealed that the representative compound 8a displayed broad-spectrum antiproliferative activity against 15 cancer cell lines with average IC50 value 10.18 ± 3.25 μM, and effective antiangiogenic activity on human microvascular endothelial cells (HMEC-1). In brief, metal complexes of naphthalimide–cyclam conjugates were firstly designed and synthesized as multi-target tyrosine kinase inhibitors and proved of their antitumor capacities.

Synthesis, crystal structure and photophysical properties of a series of metal complexes MI2L2 (M = Zn, Cd, Hg) from an imidazole derivative

A series of novel metal complexes, ZnL2I2, CdL2I2, and HgL2I2 (L: 1-[Trans-4-(4-diethylaminostyryl) phenyl] imidazole), have been prepared and fully characterized. The structure of HgL2I2 was confirmed by single crystal X-ray diffraction analysis, which exhibits that Hg atom is coordinated by two iodine atoms and two nitrogen atoms from the ligand to form a distorted tetrahedral environment. The variable temperature 1H NMR spectra proved that the metal complexes exhibit well stability in solution. Linear and nonlinear optical properties of them were described on the basis of density functional theory (DFT) calculations. Interestingly, we found that the complexation of the ligands with metal ion extends the electronic delocalization in the metal complexes, leading to dramatically enhanced two-photon absorption.

Synthesis, Characterization, and Cytotoxic Activity on MCF-7 Cell Line of Some Novel Metal Complexes With Substituted Benzimidazole Ligands

A series of novel metal complexes with the Schiff base ligands 4-((((1H-benzo[d]imidazol-2-yl)methyl)imino)methyl) benzene-1,3-diol, H3L1, and (((1H-benzo[d]imidazol-2-yl)methyl) thio)propanenitrile, HL2, have been synthesized and identified by elemental and spectral (UV-vis, IR, 1H NMR, mass) analyses, molar conductivities, as well as magnetic moment measurements technique. The ligands behave either as neutral tridentate or bidentate ligand. The antitumor activity of the new compounds was tested against breast cancer cell line MCF‐7. Ag and Cu complexes 2, 8 and 9 showed a remarkable smaller value of IC50 than that of the Tamoxifen, the standard. This would provide a new potential antitumor drug that deserves more attention.

A modular design of metal catalysts for the transfer hydrogenation of aromatic ketones

The ability of transition metal catalysts to add or remove hydrogen from organic substrates by transfer hydrogenation is a valuable synthetic tool. Towards a series of novel metal complexes with a P―NH ligand, [Ph2PNHCH2―C4H3O] derived from furfurylamine were synthesized. Reaction of [Ph2PNHCH2―C4H3O] 1 with [Ru(η6‐p‐cymene)(μ‐Cl)Cl]2, [Ru(η6‐benzene)(μ‐Cl)Cl]2, [Rh(μ‐Cl)(cod)]2 and [Ir(η5‐C5Me5)(μ‐Cl)Cl]2 gave a range of new monodentate complexes [Ru(Ph2PNHCH2―C4H3O)(η6‐p‐cymene)Cl2] 2, [Ru(Ph2PNHCH2―C4H3O)(η6‐benzene)Cl2] 3, [Rh(Ph2PNHCH2‐C4H3O)(cod)Cl] 4, and [Ir(Ph2PNHCH2‐C4H30)(η5‐C5Me5)Cl2] 5, respectively. All new complexes were fully characterized by analytical and spectroscopic methods. 31P‐{1H} NMR, distortionless enhancement by polarization transfer (DEPT) or 1H‐13C heteronuclear correlation (HETCOR) experiments were used to confirm the spectral assignments. Following activation by KOH, compounds 1, 2, 3, 4 catalyzed the transfer hydrogenation of acetophenone derivatives to 1‐phenylethanol derivatives in the presence of iso‐PrOH as the hydrogen source. Notably [Ru(Ph2PNHCH2‐C4H3O)(η6‐benzene)Cl2] 3 acts as an excellent catalyst, giving the corresponding alcohols in 98–99% yield in 20 min at 82°C (time of flight ≤ 297 h−1) for the transfer hydrogenation reaction in comparison to analogous rhodium or iridium complexes. Copyright © 2012 John Wiley &amp; Sons, Ltd.

D 3h Al3N: a novel promising ligand for coordination chemistry

Several prior experimental and theoretical studies have been reported on Al3N and have shown that the D3h isomer is the global minimum. In this work, we attempt to theoretically design new molecular materials containing the D3h Al3N as unit. A novel series of metal complexes with the Al3N ligand, including [(Al3N)K(Al3N)]+ (traditional homo-decked sandwich), [(Al3N)ZnZn(Al3N)]2+ (binuclear metallocene), and [(Al3N)Zn(C5H5)]+ (hetero-decked sandwich), are predicted to be local minima on their corresponding potential hyper surfaces at the B3LYP, B3PW91, and BP86 levels of theory with the 6–311+G(d) basis set. Natural bond orbital and AOMix analyses indicate that the interaction between the metal ions and the Al3N ligands is mostly electrostatic. This fact suggests that the Al3N is a promising ligand for coordination chemistry.