Copper Complexes Of Ligands Research Articles

Copper complexes of pyrazolone-based Schiff base ligands: Synthesis, crystal structures and antibacterial properties

Two new Cu(II) Schiff base complexes were synthesized and characterized. The corresponding NO type bidentate Schiff base ligands were synthesized from the condensation of 2,5-dimethylaniline (HL1) or 3,5-dimethylaniline (HL2) with 4-acetyl-3-methyl-1-phenyl-5-pyrazolone. Another bidentate Schiff base ligand (HL3) was also synthesized from the condensation of Prop-2-en-1-amine (allylamine) with 4-acetyl-3-methyl-1-phenyl-5-pyrazolone but all attempts to synthesize the corresponding Schiff base complex failed. The ligands and complexes were characterized by general spectroscopic techniques including 1HNMR, IR, UV–Vis spectroscopy as well as elemental analysis. Crystal structure of one of the complexes, [Cu(L1)2] was determined. Antibacterial potential of these ligands and complexes were tested against four bacteria, namely Escherichia coli (G−), Pseudomonas aeruginosa (G−), Staphylococcus aureus (G+) and Bacillus subtilis (G+). The ligands and complexes showed considerable antibacterial activity against both gram-positive and gram-negative bacteria. The ligands almost showed higher antibacterial activity than the corresponding complexes.

Studies by 1H NMR and UV-Vis spectroscopy of the molecular recognition of histamine by copper and zinc complexes of polyazamacrocyclic ligands

Abstracts The recognition of histamine with copper and zinc complexes of polyazamacrocyclic ligans was studied. The molecular recognition of histamine from the metal complexes was determined by UV-Vis and 1H NMR spectra in solution. In the coordination study of histamine with the Cu2+ complexes, different changes were observed in the charge transfer bands and in the d-d bands of the metal complexes. These observations indicate a change in the conformational geometry of the complexes and the formation of the adduct with histamine. According with the analysis by 1H NMR, the chemical shifts of the H2 and H5 hydrogens of the histamine aromatic ring are caused by the interaction with Zn2+ complexes, the widening of the H2 signal suggests that the coordination occurs between the N3 of the imidazole ring of the histamine and the Zn2+ ion. These results showed the formation of histamine adducts with the Cu2+ and Zn2+ complexes, to give rise to a ternary complex.

Solvatochromism of Copper(II) Complexes Derived from Trifluoroacetylacetone and Dinitrogen Ligands

Mixed ligand copper(II) complexes of the empirical formula [Cu (L)(TFAA)]X, where L represents 2,2´-bipyridine (Bipy), 1,10´-phenanthroline (Phen), or 4,7-diphenyl-1,10´- phenanthroline (Dphen), TFAA is 1,1,1-Trifluoro-2,4-pentanedione, and X is the counter ion (BF4- or ClO4-), were synthesized and characterized by spectroscopic, magnetic, molar conductance, elemental, and thermal analysis. Solvatochromic studies revealed that all the complexes showed bathochromic shifts. A square planar geometric structure is proposed for the perchlorate and tetrafluoroborate complexes. Spectral properties supported a square planar structure provided by the N2O2 chromophores. The mixed ligand copper complexes exhibited promising catalytic activity in the decomposition of hydrogen peroxide via the first-order reaction; the catalytic efficiency of perchlorate complexes was greater than that of tetrafluoroborate complexes. Potentiometric analyses of the aqueous mixed ligand copper complexes were carried out. The protonation constants of the free ligands and the stability constants of the complexes were determined using pH titration. The sequence of the stability of ternary complexes with respect to their ligands decreased in the order: Bipy˃ Phen˃ Dphen. The kinetic and thermodynamic parameters were calculated using the Coat-Redfern equation. The stability of the complexes was observed to be in line with the results obtained from the potentiometric analyses. The synthesized complexes were examined for their antimicrobial activity against two pathogenic bacteria (Staphylococcus aureus)as Gram-positive bacteria and (Pseudomonas fluorescens) as Gram-negative bacteria and one type of fungus (Fusarium oxysporum). The results indicated that the complexes exhibited higher antimicrobial activity than the ligands. It was also observed that perchlorate complexes had higher activity than tetrafluoroborate, and the growth of inhibitory activity of the complexes followed the order Bipy˃ Phen˃ Dphen.

ROS-mediated cell death induced by mixed ligand copper(II) complexes of l-proline and diimine: effect of co-ligand

A series of mixed-ligand Cu(II) complexes of the type: (i) [Cu(l-pro)(diimine)(H2O)n](ClO4) (n = 0 or 1), where l-pro is l-proline and diimine is 2,2′-bipyridine (bpy; 1), (ii) 4,4′-dimethyl-2,2′-bipyridine (dmbpy; 2), (iii) 1,10-phenanthroline (phen; 3), (iv) 5,6-dimethyl-1,10-phenanthroline (5,6-dmp; 4), (v) 3,4,7,8-tetramethyl-1,10-phenanthroline (3,4,7,8-tmp; 5), (vi) dipyrido-[3,2-f:2′,3′-h]-quinoxaline (dpq; 6), and (vii) dipyrido[3,2-a:2′,3′-c]phenazine (dppz; 7) have been synthesized and characterized systematically. Complexes 2 and 3 have been structurally characterized. DNA- and protein-binding and cleavage studies revealed that 7 possesses stronger DNA- and protein-binding efficiency and also exhibits self-activating DNA-cleavage in the absence of an activating agent. The hydrophobic complexes 4 and 5 induced self-activated protein cleavage and yielded a single-cleaved fragment each. The cytotoxic property of all the seven complexes was examined by incubation with the human small cell lung carcinoma cell line A549. Complexes 4 and 6 exhibited almost similar cytotoxic properties [IC50 = 1.4 µM (4) and 1.3 µM (6)], which was 9.3 and 10 times, respectively, more efficient than cisplatin (IC50 = 13 µM). Complex 4 induced generation of the highest level of intracellular ROS which correlates with its efficient cytotoxic activity and provides scope for further investigation as a potential anticancer agent.

Ligand complex of copper (II) supported on superparamagnetic Fe3O4@SiO2 nanoparticles: an efficient and magnetically separable catalyst for N-arylation of nitrogen-containing heterocycles with aryl halides

In this study, we introduce the ligand complex of copper (II) supported on superparamagnetic Fe3O4@SiO2 nanoparticles as a highly intriguing magnetic catalyst in N-arylation of nitrogen heterocycles with aryl halides. The present methodology offers several advantages such as; low catalyst loading, the use of magnetically recoverable and reusable catalyst, high to excellent yields without using any external ligands or additives, short reaction times and simplicity of operation. Also, the magnetic catalyst could be easily separated from the final product by an external magnet and reused up to seven times without any significant loss of activity. Therefore, this separation strategy with negligible leaching makes Fe3O4@SiO2/ligand/Cu(II) an economical catalyst to perform this transformation.

Erratum to: Synthesis and Structural Characterization of a Monomeric Mixed Ligand Copper(II) Complex Involving N,N,N′,N′-Tetramethylethylenediamine and Mefenamate

Erratum to: Synthesis and Structural Characterization of a Monomeric Mixed Ligand Copper(II) Complex Involving N,N,N′,N′-Tetramethylethylenediamine and Mefenamate

Oxygenation of Phenanthriporphyrin and Copper(III) Phenanthriporphyrin: An Efficient Route to Phenanthribilinones.

Photooxidation of copper(III) 5,6-dimethoxyphenathriporphyrin and copper(III) 5,6-dioxophenanthriporphyrin, which contain phenanthrene or dioxophenathrene moieties built into the macrocyclic frameworks, resulted in the regioselective cleavage that afforded organometallic copper(III) complexes of open-chain phenanthribilinone-type acyclic ligands terminated by carbonyl groups. The copper(III) coordinates two carbon atoms of phenantherene (dioxophenanthrene) and two nitrogen atoms of pyrrole and pyrrolone units, preserving the donor sets of the paternal complexes. The primary dioxygen attack is located at the meso carbon atom adjacent to the phenanthrene moiety. Demetalation of copper(III) 21-benzoyl-phenanthribilin-1-one and copper(III) 21-benzoyl-dioxophenanthribilin-1-one yielded mainly two diastereomers [15Z, 20E] and [15Z, 20Z], which differ in the configurations at two Cα-Cmeso double bonds. The regioselectivity of the cleavage, detected in the course of experimental studies, has been substantiated by DFT investigations. The regioselective cleavage of 5,6-dimethoxyphenanthriporphyrin in reaction with basic iron(III) acetate was detected, providing the synthetically efficient methodology to produce 21-benzoyl-dioxophenanthribilin-1-one.

Synthesis, spectral, electrochemical, in-vitro antimicrobial and antioxidant activities of bisphenolic mannich base and 8-hydroxyquinoline based mixed ligands and their transition metal complexes

A new series of cobalt(II), nickel(II), copper(II) and zinc(II) mixed ligand complexes, based on bisphenolic Mannich base, 2,2’-(((2-(dimethylamino)ethyl)azanediyl)bis(methylene))bis(4-(tert-butyl)phenol) and 8-hydroxyquinoline (Q) was prepared and characterized by spectroscopic techniques, magnetic study, molar conductivity and cyclic voltammetry. Spectral and magnetic data measurements are described as octahedral geometry for all the complexes. The redox behavior of metal complexes was investigated by cyclic voltammetry. All the compounds were screened for anti-bacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococci species and anti-fungal activity against Aspergillus niger, Penicillium species by the disk-agar diffusion method. All the compounds have shown better potency against the tested bacteria and fungi. Moreover, they have shown significant antioxidant capacity on the basis of an antioxidant assay.

Experimental and computational characterization of structural and spectroscopic features of mixed ligand copper complexes-prototypes for square-pyramidal stereochemistry

Two new mixed ligand copper complexes with 1,10-phenanthroline and monodentate pyrazoles (3,5-dimethyl-4-R-pyrazole, where R = nitro or iodo), stand as case-studies for a revisited view on Ligand-Field (LF) qualitative and semi-quantitative issues, brought in conjunction with the rich information offered by the state-of-the art computational methods. The combined analysis of the first TD-DFT energies and density difference maps enables a scheme of the LF split in the complexes with a specific variety of square-pyramidal coordination geometry, namely the case when the π-type anisotropy due to the two types of aromatic amine ligands shows different orientation with respect of the averaged basal plane. The density difference maps were used as ancillary tools for checking the coordination process and observing the nephelauxetic effect. Clear correlations are drawn between computed and experimental UV–Vis and EPR spectra, rationalizing the Landé factors in terms of Ligand Field states.

Synthesis and Structural Characterization of a Monomeric Mixed Ligand Copper(II) Complex Involving N,N,N′,N′-Tetramethylethylenediamine and Mefenamate

A monomeric ternary complex [Cu(tmen)(mef)2] (1) (where mef = mefenamate anion (C15H15NO21−, tmen = N,N,N′,N′-tetramethylethylenediamine) is prepared by the reaction of CuCl2·2H2O, mefenamic acid (mefH = 2-(2,3-dimethylphenyl)aminobenzoic acid), and N,N,N′,N′-tetramethylethylenediamine (tmen) in the presence of sodium hydroxide. Complex 1 is characterized by the elemental combustion analysis, UV-visible and FT–IR spectroscopy, thermal analysis, and single crystal X-ray diffraction. From the crystal structure of complex 1, it is evident that each copper(II) ion is six-coordinate and is bonded to chelating tmen, and four O atoms of two mef anions (mef1–). In the crystal, the intramolecular hydrogen bonding exists between the H atom of the –NH group of mef and the O atom of one of the coordinated carboxylate O atoms, belonging to the same mef ligand. Complex 1 is tested for antibacterial properties against four strains, including Staphylococcus aureus, Bacillus spizizenii, Escherichia coli, and Klebsiella pneumonia. The complex shows a biological activity against Staphylococcus aureus and Bacillus spizizenii.

Copper(II) complexes of coumarin-derived Schiff base ligands: Pro- or antioxidant activity in MCF-7 cells?

A series of copper(II) complexes of Schiff base-derived ligands (1–7) were studied for their pro- and antioxidant behaviour in the MCF-7 human breast cancer cell line. The coordination modes of two of the copper(II) complexes were investigated by pH-potentiometry, EPR and UV–Vis spectroscopic methods. The solution studies indicated that monomeric species are present in the Cu(II) – L1 system at neutral pH, whereas dinuclear species were observed in the case of the Cu(II) – L7 system. This difference in speciation was reflected in their relative cytotoxicities with the copper(II) complex of L1, showing significant cytotoxicity against MCF-7 cells whilst the complex of L7 was inactive. In fact, only three of the seven complexes studied in this series were cytotoxic to MCF-7 cells but this cytotoxicity did not correlate with their ability to bind to DNA, cleave DNA or act as a pro-oxidant. In contrast to previous copper(II) complexes studied by our group, the compounds studied here do not appear to lead to intracellular reactive oxygen species generation at any significant level. In a yeast-based assay, all of the copper complexes had the ability to protect Saccharomyces cerevisiae against menadione-induced oxidative stress but not hydrogen peroxide-induced stress, indicating a lack of catalase activity. Given that the adaptive mechanisms induced by hypoxia in cancer cells have selective effects, with a fine-tuned protection against damage and stress of many kinds, particularly against oxidative stress, chemotherapeutic compounds which are not pro-oxidants may offer a therapeutic advantage.

Cyclic voltammetric behavior of binary and mixed ligand copper complexes with picolinic acid, nicotinic acid and diethyldithiocarbamate in acetone medium

Cyclic voltammetric behavior of binary and mixed ligand copper complexes with picolinic acid, nicotinic acid and diethyldithiocarbamate in acetone medium

SYNTHESIS OF NEW BORON COMPOUNDS WITH AMOXICILLIN AND SOME OF ITS METAL COMPLEXES WITH USE THEM IN ANTIBACTERIAL, ASSESSMENT OF HEPATOPROTICTIVE AND KIDNEYACTIVITY, ANTICANCER AND ANTIOXIDANT APPLICATIONS

Objective: New ligand ({7-[2-amino-2-(4-hydroxyphenyl)-acetamido-3,3-dimethyl-6-oxo-2-thia-5-aza bicyclo[3,2,0]heptane-4-carboxylic boric anhydride}) with its Co (II), Ni (II) and Cu (II) complexes. And new mixed ligand copper complex was synthesized.
 Methods: The ligand was synthesized by the reaction of boric acid with amoxicillin (1:1) and the mixed ligand complex has been synthesized by the reaction of the ligand, 4-aminoantipyrine and Cu (II) ion (1:1:1).
 Results: All studied compounds were characterized by the spectral method: Fourier transform infrared, ultraviolet-visible, thermal analysis (TG and DTG), flame atomic absorption and nuclear magnetic resonance. Also CHNS, melting point, magnetic susceptibility and molar conductivity.
 Conclusion: According to the obtained data, all complexes were non electrolyte and the geometry was octahedral for all complexes. All synthesized compounds were tested as antibacterial agents against Escherichia Coli, Pseudomonas auroginosa as Gram-negative bacteria (G-) and Staphylococcus aureus epidermis as Gram-positive bacteria (G+). The results showed that copper complexes were more active in (10-2M) than the other compounds. The medicinal applications (hepatoprotective and kidney in serum of mice, histopathological of liver and kidney, anticancer and antioxidant in human cell were studied of the synthesized compounds and gave a good results in all tested.

Synthesis, Characterization, and DFT Calculations of New Fluorescent Cu(II) Complexes of Heterocyclic Ligands

The synthesis, spectral studies, and quantum chemical investigation of two new copper(II) complexes of fluorescent heterocyclic ligands derived from benzimidazole are reported. The fluorescent heterocyclic ligands are synthesized by the reduction of imidazo[4′,5′:3,4]benzo[1,2-c]isoxazole derivatives and characterized by elemental analysis, IR, mass, and NMR spectra. Coordination of the bidentate ligands with the Cu(II) cation produce orange complexes. The structures of the complexes are established by spectral, analytical data and Job’s method. To gain insight into the geometry and spectral properties of the Cu(II) complexes, DFT calculations are performed at the B3LYP/6-311++G(d,p) level. The DFT-calculated spectral properties are in good agreement with the experimental values, confirming the suitability of the optimized geometries for the copper complexes. The photophysical properties of the ligands and the Cu(II) complexes are characterized by UV-Vis and fluorescence spectroscopy. An efficient charge transfer from the ligand p orbital to the Cu(II) d orbital may be proposed as the main reason for the color of the complexes.

Controlling the Kinetics of Self-Reproducing Micelles by Catalyst Compartmentalization in a Biphasic System.

Compartmentalization of reactions is ubiquitous in biochemistry. Self-reproducing lipids are widely studied as chemical models of compartmentalized biological systems. Here, we explore the effect of catalyst location on copper-catalyzed azide–alkyne cycloadditions which drive the self-reproduction of micelles from phase-separated components. Tuning the hydrophilicity of the copper-ligand complex, so that hydro-phobic or -philic catalysts are used in combination with hydro-philic and -phobic coupling partners, provides a wide range of reactivity patterns. Analysis of the kinetic data shows that reactions with a hydrophobic catalyst are faster than with a hydrophilic catalyst. Diffusion-ordered spectroscopy experiments suggest compartmentalization of the hydrophobic catalyst inside micelles while the hydrophilic catalyst remains in the bulk aqueous phase. The autocatalytic effects observed can be tuned by varying reactant structure and coupling a hydrophilic alkyne and hydrophobic azide results in a more pronounced autocatalytic effect. We propose and test a model that rationalizes the observations in terms of the phase behavior of the reaction components and catalysts.

Copper complexes of arylselenolate-based ligands: synthesis and catalytic activity in azide–alkyne cycloaddition reactions

Arylselenolate-based copper complexes have been synthesized and used as pre-catalysts for azide-alkyne cycloaddition reactions.

Copper(ii) complexes with NNO ligands: synthesis, crystal structures, DNA cleavage, and anticancer activities.

Three novel copper(ii) complexes, Cu(L1)2 (1), Cu(L2)2·2DMF (2), and Cu(L3)2·2DMF (3), were synthesized using three aroylhydrazone ligands, (E)-2-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL1), (E)-3-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL2) and (E)-4-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL3). The complexes were characterized by elemental analysis, infrared (IR), and Ultraviolet-visible light (UV-vis) spectroscopy. The X-ray crystal structures of the complexes all possess a distorted octahedral coordination geometry. Both an absorption spectral titration and a competitive binding assay (ethidium bromide, 4',6-diamidino-2-phenylindole (DAPI), and methyl green) revealed that complexes 2 and 3 bind readily to calf thymus DNA (ctDNA) through intercalative and minor groove binding modes. Complexes 2 and 3 also exhibited oxidative cleavage of supercoiled plasmid DNA (pUC19) in the presence of ascorbic acid as an activator. Cytotoxicity studies showed that complexes 2 and 3 possessed high cytotoxicities toward the HeLa human cervical cancer cell line, but weak toxicities toward the L929 normal mouse fibroblast cell line. We therefore have reason to believe that complexes 2 and 3 both show potential as promising anticancer candidate drugs.

Highly active copper(i) complexes of aroylthiourea ligands against cancer cells – synthetic and biological studies

Copper(i) complexes containing sulfur donor monodentate aroylthiourea ligands have been synthesized and evaluated for their biological applications.

Metallomicelle catalyzed aerobic tandem desilylation/Glaser reaction in water

The copper complexes of PEG-grafted nitrogen ligands serve as metallomicellar nanoreactors for the aerobic tandem desilylation/Glaser coupling of TMS-protected alkynes in water.

Synthesis, characterization, and DFT calculations of new fluorescent Cu(II) complexes of heterocyclic ligands

The synthesis, spectral studies, and quantum chemical investigation of two new copper(II) complexes of fluorescent heterocyclic ligands derived from benzimidazole are reported. The fluorescent heterocyclic ligands are synthesized by the reduction of imidazo[4',5':3,4]ben­zo[1,2-c]isoxazole derivatives and characterized by elemental analysis, IR, mass, and NMR spectra. Coordination of the bidentate ligands with the Cu(II) cation produce orange complexes. The structures of the complexes are established by spectral, analytical data and Job's method. To gain insight into the geometry and spectral properties of the Cu(II) complexes, DFT calculations are performed at the B3LYP/6-311++G(d,p) level. The DFT-calculated spectral properties are in good agreement with the experimental values, confirming the suitability of the optimized geometries for the copper complexes. The photophysical properties of the ligands and the Cu(II) complexes are characterized by UV-Vis and fluorescence spectroscopy. An efficient charge transfer from the ligand p orbital to the Cu(II) d orbital may be proposed as the main reason for the color of the complexes.