Mixed Ligand Nickel Research Articles

Synthesis, structure, and biological activities of mixed-ligand nickel(II) and cobalt(II) complexes of benzoylhydrazone 2-(N-tosylamino)benzaldehyde and benzimidazole derivatives

The synthesis of four new nickel(II) and cobalt(II) complexes based on 2-(N-tosylamino)benzaldehyde benzoylhydrazone (H2L), with additional heterocyclic donor ligands Ln, NiHLLn and CoHLLn(Ac) (n = 1, 2), has been carried out (where L1 = 1-propyl-2-aminobenzimazole, L2 = 1-hexyl-2-aminobenzimidazole, and Ac = acetate). The compositions and structures of these compounds were determined using elemental analysis, 1H NMR spectroscopy, and IR spectroscopy. Single-crystal X-ray diffraction was used to determine the molecular structures of the nickel(II) and cobalt(II) complexes. It has been found that in NiHLLn, the ions of nickel(II) have a distorted flat-square environment, whereas the coordination sphere of the cobalt(II) in CoHLLn(Ac) can be described as a strongly distorted square pyramid due to additional coordination with the acetate group. The biological activity of the compounds has been investigated. The results showed that all complexes exhibited significantly higher antiprotozoal activity compared to the reference drug chloroquine.

Synthesis, structure, and mechanism of action of a unique mixed-ligand nickel (II)-complex of tetra-dentate phenol-based ligand with di-aquo co-ligands with significant pro-apoptotic and anti-metastatic effect against malignant human cancer cells

From the discovery of the anticancer activity of “cisplatin”, various type of numerous mononuclear platinum (II) complexes has been evaluated for antitumor activities, though therapeutic use is limited due to side effects and resistance. In this study, A unique mixed ligand mono nuclear octahedral Ni (II) complex [NiL(H2O)2].0·.5H2O (1) [H2L = N,Nʹ-dimethyl-N,Nʹ-bis (2-hydroxy-3,5-di methyl benzyl)-ethylenediamine] with tetra dentate phenol based ligand with N2O2 donor environment along with two labile water molecules was synthesised. The complex (1) is structurally characterized by spectroscopic tools including single-crystal X-ray diffractometer. Complex (1) crystallizes in monoclinic space group P21/n with a = 10.4871(17) Å, b = 20.860 (4) Å and c = 20.955(4) Å. The UV – visible spectra show two peaks around 507 nm and 367 nm due to spin-allowed 1A1g → 1A2g and 1A1g → 1B1g transitions respectively as expected for a square planar d8 system. Mixed ligand octahedral nickel (II) complex with facially coordinating tetra dentate phenol-based ligand (H2L) is in association with two water molecule as ancillary ligand. Two water molecules associated with coordination zone of nickel (II) centre is loosely bound. In this present study, we have evaluated the anti-cancer properties of Complex (1). We found that Complex (1) show potent cancer cell killing activity in case of poorly invasive mice and human cancer cell lines. Complex (1) trigger apoptosis chiefly via p53 dependent pathway. Complex (1) also inhibits cancer cell migration and epithelial to mesenchymal transition in case of metastatic breast cancer cells suggesting potent anti-cancer properties of complex (1).

Mixed-Ligand Nickel(II) Complexes with Histidine and Cysteine in Aqueous Solution: Thermodynamic Approach

Mixed-Ligand Nickel(II) Complexes with Histidine and Cysteine in Aqueous Solution: Thermodynamic Approach

Mixed ligand complexes of nickel (ii): Synthesis and bio medicinal studies

Mixed ligand nickel (II), complexes of 2, 2 bipridyle and thioamides of 2-aminopyridine, 2-aminoadinine, 2-aminoguanine and 2-aminocytocine were prepared. The success of synthesis was confirmed through physical and spectral characterization on the basis of IR and NMR spectroscopy, antimicrobial and antitumour studies. The synthesized compounds were found to be active against the tested three bacterial strains (Pseudomanas auruginosa, Klebseila pneumonia and Staphylococcus aureus), two fungal strains (Aspergillus flavus and Aspergillus nigar) and antitumour activity against MCF-7 (Human breast adenocarcinoma) cell line.

Thermodynamics of Mixed-Ligand Nickel(II) Complex Formation with Ornithine and Histidine in Aqueous Solutions

Thermodynamics of Mixed-Ligand Nickel(II) Complex Formation with Ornithine and Histidine in Aqueous Solutions

New asymmetric bisthiocarbohydrazones and their mixed ligand nickel(II) complexes: Synthesis, characterization, crystal structure, electrochemical-spectroelectrochemical property, antimicrobial and antioxidant activity

New asymmetric isatin bisthiocarbohydrazone ligands were synthesized by the condensation of 3,5-dibromosalicylaldehyde, 3,5-dichlorosalicylaldehyde and 3-bromo-5-chlorosalicylaldehyde with isatin monothiocarbohydrazone. New mixed ligand Ni(II) complexes were synthesized from these ligands using triphenylphosphine (PPh3) as a secondary ligand. The synthesized ligands and complexes were characterized by elemental analysis, FT-IR, 1H NMR, UV–Vis spectroscopy and mass spectrometry techniques, along with conductivity measurements. The ligands bind to the Ni(II) ion as ONS donors. The fourth coordination site is completed by the secondary ligand PPh3. The single crystal structures of one ligand and one complex were also resolved by X-ray crystallography. The electrochemical responses of the ligands and their complexes were determined and the results were evaluated to illustrate the influence of the substitution of different groups on the ligands. While the free ligands only give one oxidation peak, two oxidation peaks are observed for the Ni(II) complexes. Complexation of the ligands with the Ni(II) ion considerably affected the in-situ spectroelectrochemical responses of the ligands. Finally, the in vitro antioxidant and antimicrobial activities of the synthesized compounds were determined.

Synthesis, Characterization and Luminescent Properties of Mixed-Ligand Nickel Complexes for Opto-Electronic Application

This paper reports the synthesis of a mixed ligand nickel complexes as an emissive layer in organic light emitting diode applications. Synthesized ligand and nickel complexes were characterized by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, mass spectroscopy, x-ray powder diffraction and scanning electron microscopy. This compound shows good thermal stability and film forming properties. Optical properties have been studied by UV–vis and photoluminescence (PL). Frontier molecular orbital theory energy levels of these compounds were demonstrated using density functional theory calculations. Photoluminescence (PL) emission peaks of complexes (1) and (2) show at 596 nm and 581 nm in solid state, respectively. The structure of the fabricated multi-layered device is: ITO/αNPD(300 A)/(1)(350 A)/BCP(60 A)/Alq3(280 A)/LiF(10 A)Al(1500 A) and ITO/αNPD(300 A)/(2)(350 A)/BCP(60 A)/Alq3(280 A)/LiF(10 A)Al(1500 A). Electroluminescence emission of devices (1) and (2) containing nickel complexes as the emissive layer emit at 568 nm and 561 nm, respectively. Commission Internationale de l’Eclairage chromaticity colour coordinates of devices (1) and (2) were found to be x = 0.426, y = 0.425 and x = 0.473, y = 0.447, respectively, which emits an orange colour. These results show that these nickel complexes can act as a promising emissive layer in opto-electronic applications as strong electroluminescent materials.

Mixed-ligand nickel(ii) and copper(ii) complexes in competitive chelation reactions with polyaminopolyacetate and polyamine ligands

The mixed-ligand and competitive formation of coordination compounds in aqueous solutions of ternary systems containing nickel(ii) or copper(ii) cations, polyaminopolyacetate (nitrilo triacetic, ethylenediaminetetraacetic, or diethylenetriaminepentaacetic acid), and polyamine (ethylenediamine, diethylenetriamine, or triethylenetetramine) ligands was studied by spectrophotometry. The factors were determined which facilitate the formation of mixed-ligand complexes of composition [ML1L2] (M is NiII or CuII, L1 is a polyaminopolyacetate chelating agent, L2 is a polyamine ligand) in aqueous solutions. In these complexes, amines act predominantly as polydentate chelating ligands and the coordination sphere of metal atoms is completed by nitrogen and oxygen atoms of the chelating agents. An increase in the denticity of the polyamine ligand was found to increase the number of ethylenediamine metallocycles and promote partial cleavage of glycinate rings of carboxylate ligands in the coordination polyhedron of the chelate, thereby providing an increase in the stability of the resulting mixed-ligand complex species. In systems containing copper(ii) cations, the ability of polyamine ligands to exhibit a discriminatory effect and block the coordination of the polyaminopolyacetate chelating ligand was shown to vary and depend on the combination of L1 and L2 ligands in the coordination sphere.

Mixed-Ligand Cobalt(II) and Nickel(II) Complexes with N,N,-Diethylpyridine-3-carboxamide: Synthesis and Crystal Structure

The new complexes [M(NKA)2(NCS)2(H2O)2], where M2+ = Co2+ (I), Ni2+ (II); NKA = C10H14N2O (N,N-diethylpyridine-3-carboxamide, nicotinic acid diethylamide, nikethamide), have been synthesized and studied by chemical and X-ray diffraction analyses and IR spectroscopy. The single-crystal X-ray diffraction analysis of these complexes has shown that they crystallize in triclinic system with space group $$P\bar {1}.$$ Despite similar molecular structures of the two complexes, the orientation of molecules in a crystal cell is different in them. The coordination polyhedron of the metal atom is a distorted octahedron built of the O atoms of two coordinated water molecules, the two N atoms of the pyridine rings of two NKA molecules, and the two N atoms of rhodanide groups. The packing of molecules leads to the appearance of additional stacking interactions with the formation of a branched network of hydrogen bonds between coordinated water molecules and NKA carbonyl groups in the structures of these complexes.

Syntheses of Coordination Compounds of (±)-2-Amino-3-(4-Hydroxyphenyl)Propionic Acid, Mixed Ligand Complexes and Their Biological Activities

Coordination compounds of (±)-2-amino-3-(4-hydroxyphenyl) propionic acid and their mixed ligand complexes with 1,10-phenantroline were synthesized, characterized using electronic and infrared spectral analyses and magnetic susceptibility. The compounds were evaluated for antimicrobial and antioxidant activities. Four different assays were applied for evaluating antioxidant capacity of the compounds. The results obtained indicated a diametric square planar geometry for both cobalt (±)-2-amino-3-(4-hydroxyphenyl) propionic acid complex and its mixed ligand complex. It was suggested that for the binary cobalt(II) complex, the phenolic substituent coordinated with neighbouring central metal ions. However, for the ternary cobalt(II) complex it was suggested it was deprotonated. Octahedral geometry was proposed for both copper complexes. Square planar geometry was indicated for the nickel (±)-2-amino-3-(4-hydroxyphenyl) propionic acid complex and a mixture of square planar and octahedral geometry for the nickel mixed ligand complex. The cobalt mixed ligand complex elicited the highest activity for all the antioxidant assays. In most cases the binary complexes exhibited better antimicrobial activities relative to their ternary counterparts.

New square-planar nickel(II)-triphenylphosphine complexes containing ONS donor ligands: Synthesis, characterization, electrochemical and antioxidant properties

Five new mixed ligand nickel(II) complexes with the general formula [Ni(L)(PPh3)], [C1–C5], were prepared from the reaction of triphenylphosphine (PPh3) with ONS donor ligands (L) [where R = Η (L1); 4-OCH3 (L2); 4-OCH2(CH2)6CH3 (L3); 4-OCH3, 4′-CH3 (L4) and 4-OCH2CHCH2 (L5)] derived from 2-hydroxybenzophenones and thiocarbohydrazide. The structures of the complexes were characterized by elemental analysis, IR, 1H and 31P NMR spectroscopy, conductivity measurements. The crystal structures of ligand (L2) and complex (C2) were determined by single crystal X-ray diffraction method. The ligand is coordinated to the nickel core through the phenolate oxygen, azomethine nitrogen and sulfur atoms, while the fourth coordination site is occupied by the P atom of a triphenylphosphine ligand. X-ray analysis indicated distorted square-planar structure for the complex C2. Electrochemical behaviors of thiocarbohydrazone ligands (L1-L5) and their nickel(II) complexes (C1–C5) were studied and effects of the type of substituents were compared. All ligands illustrated two irreversible reductions and one irreversible oxidation. Complexing of the ligands with Ni(III) ion considerably influenced their redox behaviors. Electron transfer process of the complexes get easier and became more reversible when compared with those of the corresponding ligands. Moreover, Ni(II) complexes illustrated NiII/NiI and NiII/NiIII processes in addition to the ligand-based electron transfer reactions. In-situ spectroelectrochemical responses of the ligands considerably changed after formation of Ni(II) complexes. Total antioxidant capacity and free radical scavenging activity of the compounds have been tested using CUPRAC and DPPH methods, respectively. The results of Ni(II) complexes were compared with a standard antioxidant compound.

Thiosemicarbazone ligand, nickel(II) and ruthenium(II) complexes based on vitamin B6 vitamer: The synthesis, different coordination behaviors and antioxidant activities

Mixed ligand nickel(II) and ruthenium(II) complexes were synthesized from pyridoxal-N-allyl-thiosemicarbazone hydrochloride and triphenylphosphine. The structures of the complexes have been characterized by elemental analysis, IR, 1H and 31P NMR, conductivity, magnetic moment measurements and single-crystal X-ray diffraction technique. Based on X-ray crystallographic studies, a square-planar structure has been proposed for the Ni(II) complex, in which the thiosemicarbazone ligand acts as dianionic tridentate ONS ligand. In the case of the Ru(II) complex, the thiosemicarbazone is coordinated to metal atom as a monoanionic bidentate NS donor ligand in an octahedral geometry. Antioxidant activities of the ligand and its metal complexes were calculated as their trolox equivalent antioxidant capacities (TEAC) by CUPRAC method and DPPH assay. Both the ligand and its metal complexes were found to be antioxidant and are much more antioxidant at least 2.1 times than trolox, even, ligand is 3.5 times greater than that of trolox according to CUPRAC. A linear correlation (correlation coefficient R2 = 0.9997) appeared between the obtained TEAC values by the two antioxidant assays.

Synthesis, Physicochemical Studies and Biological Properties of Mixed-Ligand Nickel(II) Complexes Containing β-Diketones With N-donor Ligands

Some mixed ligand nickel(II) complexes of thenoyltrifluoroacetone (tta-H) with 2,2ꞌ-bipyridine (bipy), 1,10-phenanthroline (phen) and tetramethylethylenediamine (tmen) [Ni(tta)(N-N)(NO3)]; N-N= bipy, phen, or tmen] have been synthesized and characterized by molar conductance measurements, elemental analysis, mass spectrometry, spectral measurements and antimicrobial activities. Attempt to prepare the mixed ligand nickel(II) complexes containing acetylacetone (acacH), benzoylacetone (bzacH), dibenzoylmethane (dbm-H) and thenoyltrifluoroacetone (tta-H) with ethylenediamine associated with NO3 counter ion led to the formation of [Ni(β-diketone)2en]. The β-diketones enolized acting as bidentate ligand, coordinating to the metal with carbonyl and enolic oxygen, ethylenediamine (en) coordinates to the metal using N, N chromophores. The nickel complexes of the type [Ni(tta)(N-N)NO3)] are five-coordinate square pyramidal in geometry while those of the type [Ni(β-diketone)2en] are six-coordinate octahedral geometry. The conductivity measurement in nitromethane revealed that the [Ni(tta)(N-N)NO3)] complexes are non-electrolyte. The complexes were screened for their in-vitro antimicrobial activity against six microorganisms. A comparison of the complexes with gentamicin showed that most of the complexes are resistant to tested organisms except [Ni(tta)2(en)].H2O, [Ni(bzac)2(en)] and [Ni(bta)2(en)] which compared favourably well in Staphylococcus aureus.

English

English

Synthesis, crystallographic and spectroscopic studies, evaluation as antimicrobial and cytotoxic agents of a novel mixed-ligand nickel(II) complex

A new mononuclear mixed-ligand complex of Ni(II) has been synthesized and structurally characterized by single-crystal X-ray diffraction as [Ni(4-Cl-pydc)(apym)(H2O)2], where 4-Cl-pydc and apym are 4-chloropyridine-26-dicarboxylate and 2-aminopyrimidine, respectively. Spectroscopic studies such as FT-IR, UV-vis, 1H-NMR, and thermal analysis (TGA/DTA) were carried out. The fluorescence properties were studied in solvents with different dipole moments. Antimicrobial activities of 4-chloropyridine-26-dicarboxylic acid (1), 2-aminopyrimidine (2), complex (3), and nickel(II) nitrate hexahydrate (4) were investigated by disk diffusion and broth microdilution methods against three Gram-positive bacteria, Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis and three Gram-negative bacteria, Escherichia coli, Pseudomonas aeruginosa, S. marcescens; also antifungal effect was evaluated on Aspergillus niger and Saccharomyces cerevisiae in vitro. The highest antibacterial activity of complex was observed nearly equal to gentamicin as a standard drug toward S. epidermids with IZD of 18 mm. The in vitro antiproliferative activity of 1–4 on H1299 (a human non-small cell lung carcinoma), HepG2 (a human liver hepatocellular carcinoma), and β-TC3 (a mouse beta pancreatic) cell lines was evaluated by MTT (3-(45-dimethylthiazol-2-yl)-25-diphenyl-2H-tetrazolium bromide) assay and, effect of complex on depolarization of mitochondrial membrane (MMP) of all three cell lines was measured by rhodamine 123. The highest cytotoxic effect of complex was exhibited toward H1299 cell line with IC50 value equal to 10 μM.

Theoretical calculations, DNA interaction, topoisomerase I and phosphatidylinositol-3-kinase studies of water soluble mixed-ligand nickel(II) complexes

Eight water soluble mixed-ligand nickel(II) complexes of the type [NiL1–4(diimine)H2O]·(ClO4)2, (1–8) where L1−4 = 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols, and diimine = 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen) were synthesized and characterized by elemental analysis and spectroscopic methods. The uncoordinated perchlorate anions was ascertained form IR spectra of the complexes, and the absorption spectra reveal the octahedron geometry around nickel(II) ion with tridentate Schiff base ligand, diimine and a coordinated water molecule. Cyclic voltammograms of the complexes indicate the one-electron irreversible processes in the cathodic and anodic region. In vitro antioxidant activity proved the significant radical scavenging activity of the complexes against DPPH radical. The groove/electrostatic binding nature of complexes with CT–DNA (calf thymus deoxyribonucleic acid) were affirmed by absorption, hydrodynamic and voltammetric titration experiments and docking analysis. All the complexes exhibit significant cleavage activity on plasmid DNA via hydrolytic and oxidatively, in which the oxidative mechanism involves hydroxyl radicals and supports the possibility of minor-groove binding. The complex 4 shows significant topoisomerase I (Topo-I) inhibitory activity. The molecular modeling analysis of complexes with phosphatidylinositol-3-kinase (PI3K) receptor indicate the hydrogen bonding with Met1039, Asp837 and Leu1027, and hydrophobic interactions with Ser488, Asn498, Asp500, Gln662, Lys668, Ile844, Ile847, Ile850, Val941, Leu942, Leu1020, Met1034, Leu1035, Thr1037, Met1039, Gln1041 and Ile1051 of subdomain IIA of BSA. The complexes show σ–π interaction between diimines and amino groups of Leu1030 and Arg839.

DNA Binding Properties of Water-Soluble Mixed Ligand Nickel(II) Complex with Calf-thymus DNA Using Different Instrumental Methods

The binding ability of the a water-soluble nickel(II) complex with pyridine-2,6-dicarboxylic acid (pydcH2) and 2-aminopyrimidine (amp) formulated as [Ni(pydc)(amp)].2H2O].H2O (1) to calf-thymus (CT-DNA) was investigated. The binding ability of 1 was studied by measuring the effects on the electronic absorption spectra, thermal denaturation studies, fluorescence quenching studies by using methylene blue (MB) as a fluoresce probe, and circular dichroism (CD) spectra. All the results suggest the interaction modes between 1 and DNA were partial intercalation with a binding constant of (8.43 ± 0.2) × 104 M−1.

Synthesis, molecular orbital, optical and device characterization of mononuclear mixed ligand nickel(II) complex of phthalate with N,N,N′,N′-tetramethylethylenediamine for photodiode applications

In this work, a new synthesized mononuclear mixed ligand nickel(II) complex was characterized by various techniques. Crystalline characteristics of [Ni(Phth)(Me4en)(H2O)2]·4H2O were studied by using transmission electron microscope(TEM). Well crystalline structure corresponds to the hexagonal crystal system and identified by selected area electron diffraction (SAED) were achieved. Coordination of the nickel(II) ion with the functional groups of the ligands was established from the IR spectrum. Molar conductance of the current complex in DMF (10−3mol/L) indicated a non-electrolytic nature of the complex. Electronic spectra showed a strong band in the region 661–684nm; MeCN (661nm), CHCl3 (663nm), MeOH (667nm), Me2CO (675nm), DMSO (682nm) and DMF (684nm) which can be assigned to 3A2g(F)→3T1g(F) transition of an octahedral structure around nickel(II). Multiple peaks were easily resolved from the spectral dependence of the absorption coefficient (α) measurements and the analysis near the fundamental absorption edge showed two direct allowed transition with energy gaps of 1.18 and 2.53eV. Dark current–voltage and capacitance–voltage characteristics of [Ni(Phth)(Me4en)(H2O)2]·4H2O/n-Si heterojunctions were studied to extract the main important parameters of the heterojunction device. The electrical characteristics of the heterojunction device under illumination hold the suitability of the device for optoelectronic applications.

Four related mixed-ligand nickel(ii) complexes: effect of steric encumbrance on the structure, DNA/BSA binding, DNA cleavage and cytotoxicity

Four new interrelated mixed-ligand nickel(ii) complexes have been synthesized and characterized. The activities of DNA binding/cleavage, BSA binding with complexes and the vitro cytotoxicity also have been explored.

Electrochemistry and structural properties of new mixed ligand nickel(ii) complexes based on thiosemicarbazone

Mixed ligand nickel(II) complexes of 5-chloro-2-hydroxybenzophenone-N-R-thiosemicarbazone (R: –CH3 (L1), –CH2–CHCH2 (LII)) and triphenylphosphine were synthesized. The structures of the complexes were characterized by elemental analysis, IR, 1H and 31P NMR spectroscopy, conductivity, electrochemical and magnetic moment measurements, and single-crystal X-ray diffraction technique. The two nickel(II) complexes have a square planar geometry containing O, N, and S atoms of the thiosemicarbazone, and the P atom of triphenylphosphine. The electrochemical behaviors of the thiosemicarbazone ligands and the nickel complexes were studied using cyclic voltammetry and square wave voltammetry. The redox processes of the compounds were significantly influenced by the central metal ions and the nature of the substituents on the thiosemicarbazones, which are the important factors in controlling the redox properties. In situ spectroelectrochemical studies were employed to determine the colors and spectra of the electro-generated species of the complexes.