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A series of mononuclear Cu(II) complexes were synthesized using a potential tetradentate hydrazone ligand obtained from the reaction between phenylhydrazine groups and 2,5-thiophenedicarboxaldehyde. The structures of ligands and complexes were elucidated through various spectroscopic techniques, confirming their composition. All complexes were found to adopt four-coordinated geometries, indicating the formation of stable structures. Spectroscopic analysis revealed that the hydrazone ligand coordinated with the Cu(II) metal ions as a dibasic tetradentate ligand by utilizing the phenolic oxygen and azomethine nitrogen atoms. The binding affinity of the complexes with calf thymus DNA (CT-DNA) was investigated using absorption and viscosity measurements, demonstrating their interaction through the intercalation mode. The binding studies showed that the Cu(II) complexes exhibited varying degrees of binding affinity, with Cu(L4) demonstrating the highest affinity, followed by Cu(L1), Cu(L2), and Cu(L3). Moreover, the DNA fragmentation properties of the Cu(II) complexes were evaluated, suggesting their potential utilization in pharmaceutical applications. The obtained results highlight the significance of these novel complexes in the field of medicinal chemistry.

[Display omitted] A new C 2 -symmetric Schiff base ligand (H 2 L) featuring a core resorcinol bridging unit has been created, utilizing the Duff formylation reaction followed by the Schiff base condensation reaction. The ligand was characterized by various spectroscopic techniques. Cu(II) salts with varying coordinating anions (Cl− and SCN−) in methanol were allowed to react with this ligand in a 2:1 M ratio to create dinuclear Cu(II) complexes. The complexes were isolated in pure form and characterized by, elemental analysis,single crystal X-ray crystallography and various spectroscopic techniques. X-ray analysis discloses that both complexes are dinuclear, where the ligand (H 2 L) being tridentate in nature, coordinates to Cu(II) through its two N donor atoms and one O donor atom in the equatorial positions. The respective anions (−Cl− for 1 and –SCN− for 2) coordinate to Cu(II) to complete its square planar geometry. Temperature dependent magnetic susceptibility measurements indicate weak antiferromagnetic exchange interactions with a coupling constant of J = −5.9(1) cm−1 and g = 2.148(1) for 1 and J = −10.08(1) cm−1 and g = 2.106(1) for 2. [ABSTRACT FROM AUTHOR]

Although the interaction between the β-amyloid peptide and copper (II) appears to play an important role in Alzheimer's disease, the affinity constant is still controversial and values are ranging from 107 to 1011 M−1. With the aim of clarifying this point, a complementary method, based on the capillary electrophoresis–ICP–MS hyphenation, was developed and competitive binding experiments were conducted in the presence of nitrilotriacetic acid. The effect of the capillary surface (neutral or positively charged) and nature of the buffer (Tris or Hepes) have been studied. Tris buffer was found to be inappropriate for such determination as it enhances the dissociation of copper (II) complexes, already occurring in the presence of an electric field in capillary electrophoresis. Using Hepes, a value of 1010 M−1 was found for the affinity of the small β-amyloid peptide 1–16 for copper (II), which is in agreement with the values obtained for other proteins involved in neurodegenerative diseases. These constants were also determined in conditions closer to those of biological media (higher ionic strength, presence of carbonates). [ABSTRACT FROM AUTHOR]

In this work, we present the results from a chemical speciation study of binary and ternary complexes formed by Cu(II) with 2-(benzo[d]thiazol-2-yl)nicotinic acid (HL) and the amino acids: Aspartic acid (H2Asp, H2B), Glutamic acid (H2Glu, H2B), Histidine (HHis, HB), Serine (HSer, HB), Threonine (Thr, HB), Phenylalanine (HPhe, HB) and Methionine (HMet, HB). The analysis is based on the use of potentiometric data analysed with the least-squares programme LETAGROP in 1 M NaCl aqueous solution at 25°C. [ABSTRACT FROM AUTHOR]

Two new copper (II) complexes with the third generation quinolone antibacterial agent levofloxacin, 2‐aminopyridine and 2,2′‐bipyridine nitrogen‐based ligands with the following molecular structures [Cu (levo)2(2‐ampy)].6.25H2O (1) and [Cu (levo)(H2O)(2,2‐bipy)](NO3).2.5H2O (2) were synthesized. The complexes were characterized by spectroscopic methods and others. The crystal structure of complex 1 revealed that the Cu (II) cation is coordinated to two bidentate chelating levofloxacinato ligands, and one monodentate 2‐ampy ligand in the axial position forming a slightly distorted square pyramidal geometry. The mononuclear cationic complex 2 was determined in the triclinic crystal system and the chiral space group P1 with four molecules per unit cell in which the Cu (II) cation is coordinated to one bidentate chelating levofloxacinato ligand, one bidentate 2,2‐bipy, and one water molecule in a distorted square pyramidal geometry. In vitro antibacterial activities for the complexes and their parent ligands against four gram‐negative bacteria (Proteus mirabilis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia) and four gram‐positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, and Enterococcus faecalis) using the agar diffusion method have been determined with inhibition zone diameter (IZD) values between 29 and 46 mm. In addition, the minimum inhibition concentration (MIC) and the minimum bactericidal concentration (MBC) have been investigated. The MIC results of complexes 1 and 2 showed significant antibacterial activities against the P. mirabilis and B. subtilis than levofloxacin. [ABSTRACT FROM AUTHOR]

Two dinuclear Cu (II) and Ni (II) complexes of the general formula [Cu2L2], (1), and [Ni2L6].4 (C2H5OH), (2), which L=8-Hydroxyquinoline have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopic methods. The crystal structure analysis showed the binuclear structure for 1 and the Cu (II) centers adopt a distorted square pyramidal geometries. Two Cu centers in complex 1 are linked via µ-O coordination bridge modes of 8-hydroxyquinoline ligands with the Cu-Cu distances of 3.534 Å. The electrochemical behavior of the free ligand and corresponding 1 and 2 complexes was studied in DMF. The cyclic voltammetry of the complexes 1 and 2 show an irreversible metal and ligand based reductions at negative potentials. The electrocatalytic activity of the complexes 1 and 2 was monitored for CO2 reduction in DMF solution. The results show that the complexes can be used as new electrocatalysts for CO2 reduction, leading to formation of carbon monoxide product.

Binuclear complexes of have been synthesized by the reaction of aromatic diamine with ternary complexes of copper (II) with 2,2'-bipyridyl or 1,10-phenanthroline (as primary ligand) and 2-hydroxybenzaldehyde or 2-hydroxynaphathaldeyde or 2-hydroxyl-3-methoxybenzaldehyde (as secondary ligand). Copper (II) complexes have been characterized using various physicochemical and various spectroscopic methods (IR, ESR and mass spectrometry). The variable temperature magnetic susceptibility (90Kto300K) measurements showed weak antiferromagnetic to ferromagnetic exchange between the proximate Cu (II) ions in a complex. Molecular modeling has been used to acquire various geometrical parameters of the complex and correlated with the magnetic property. [ABSTRACT FROM AUTHOR]

We report a protocol for the evaluation of theoretical half-wave potential (E1/2) using a set of 22 mixed chelate copper (II) complexes containing 1,10-phenanthroline and 2,2′-bipyridine derivatives as primary ligands, and acetylacetonate or glycinate as secondary ligands (formally from the Casiopeínas® family) for which accurate experimental values were determined in a 2/5 mixture of ethanol/water. We have calibrated the BP86, PBE, PBE0, B3LYP, M06-2X, and ω-B97XD functionals, using the Los Alamos LANL2DZ and Stuttgart-Köln SDDAll effective core potentials for the Cu and Fe atoms and the 6-311+G* basis set for the C, H, O, and N atoms. To address the solvent effects, we have saturated the first solvation shell with up to 9 water molecules for the explicit model and compared it with the Continuum Like-Polarizable Continuum Model (CPCM) implicit solvent scheme. We found that the PBE/LANL2DZ-6-311+G* protocol (with the CPCM implicit solvent scheme with an effective dielectric constant ε = 64.9121 for the 2/5 mixture of ethanol/water) yields the overall best performance. The theoretical values are compared with experimental data, three of which are reported here for the first time. We find good correlations between the theoretical and experimental E1/2 values for the 2,2′-bipyridine derivatives (R2 = 0.987, MAE = 86 mV) and 1,10-phenanthroline derivatives (R2 = 0.802, MAE = 58.4 mV). The correlation trends have been explained in terms of the copper atom's ability to be reduced in the presence of the ligands. The Gibbs free energy differences at 298 K obtained for the redox reactions show that the more flexible secondary ligands (acetylacetonate) lead to larger entropic contributions which, as expected, increase the average MAE values as compared with the more rigid ligands (glycine). The present protocol yields lower MAEs as compared with previous approaches for similar mixed and flexible Cu(II) complexes. [ABSTRACT FROM AUTHOR]

A series of eight copper (II) complexes with 3-(4-chloro-3-nitrophenyl)thiourea were designed and synthesized. The cytotoxic activity of all compounds was assessed in three human cancer cell lines (SW480, SW620, PC3) and human normal keratinocytes (HaCaT). The complexes 1, 3, 5, 7 and 8 were cytotoxic to the studied tumor cells in the low micromolar range, without affecting the normal cells. The complexes 1, 3, 7 and 8 induced lactate dehydrogenase (LDH) release in all cancer cell lines, but not in the HaCaT cells. They provoked early apoptosis in pathological cells, especially in SW480 and PC3 cells. The ability of compounds 1, 3, 7 and 8 to diminish interleukin-6 (IL-6) concentration in a cell was established. For the first time, the influence of the most promising Cu (II) complexes on intensities of detoxifying and reactive oxygen species (ROS) scavenging the enzymes of tumor cells was studied. The cytotoxic effect of all copper (II) conjugates against standard and hospital bacterial strains was also proved.

The "pyramid effect" on EPR and electronic spectra via Ligand Field. 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. [ABSTRACT FROM AUTHOR]

The fungi of the genus Fusarium include several phyto-pathogenic species capable of attacking a large number of plants, causing diseases called fusarioses. We investigated the antifungal activity on this type of fungus. We examined in vitro a series of copper (II) complexes derivatives that were differently substituted into groups; Electron-donating or electron-withdrawing against three fungal strains: Fusarium culmorum, Fusarium graminearum and Fusarium verticillioides. Using the agar dilution method to determine the inhibitory power exerted by these complexes at a concentration of 1 mg / ml and hymexazol was used as a standard fungicide. The results show that the highest mycelia inhibition of the fungal strains is carried out for the complex [Cu-(SA-p-Cl)2] with a 42.57 ± 0.63% inhibition against the species Fusarium graminearum. However, low activity was revealed for the complex [Cu-(SA-o-Cl)2] at inhibitory power of 6.41 ± 0.35%. We have noted that the copper (II) complexes with the para-substituted Schiff bases represent a better activity against the Fusarium culmorum, F. graminearum and F. verticillioides strains. The diversity of antifungal activity is influenced by the presence of the various substituted groups (methyl, methoxy, chloro and nitro) on the structure of the copper (II) complexes examined. [ABSTRACT FROM AUTHOR]

• Two distinct g values (g ‖ and g ⊥) indicate axial symmetry for the copper(II) complexes. • Excellent anti-TB activity of ligands and complexes. • Pharmacokinetics (effective transport of molecule to their target sites) studied using drug-protein binding study of molecules with human serum albumin (HSA). • Interaction of ligands and their complexes with mycobacterium tuberculosis enoyl reductase was studied by molecular docking. Reaction of copper (II) acetate with 2,5 thiophenedicarboxaldehyde bisthiosemicarbazone (2,5 H 2 bttsc, 1H 2 L), 2,5 thiophenedicarboxaldehyde-N1-methyl bisthiosemicarbazone (2,5 H 2 bttsc-N1-Me, 2H 2 L) and 2,5 thiophenedicarboxaldehyde -N1-phenyl bisthiosemicarbazone (2,5 H 2 bttsc-N1-Ph, 3H 2 L) in 1:1 (M:L) molar ratio yielded complexes of stoichiometry, [Cu(L)] 1-3 (1L, 1; 2L 2; 3L 3). All the complexes are characterized using elemental analysis FTIR, Mass and ESR spectroscopy. The two distinct g values, g ‖ = 2.40 (1), 2.15 (2), 2.20 (3) and g ⊥ = 2.08 (1), 2.07 (2), 2.12 (3) indicate axial symmetry for the complexes. The greater g ‖ value than g ⊥, confirms the presence of free electrons in d x2-y2 ground term in square planar geometry. The ligands (1H 2 L - 3H 2 L) and their complexes (1–3) were tested for DPPH radical scavenging, ABTS radical scavenging, FRAP ferric reducing, and CUPRAC cupric reducing antioxidant capacity assays. In general, all the ligands and their metal complexes exhibited moderate antioxidant potential, however 3H 2 L has shown best Cu2+ reducing activity (7.34 μg TE/ml) and ABTS radicals scavenging activity (IC 50 , 16.95) amongst all. Ligands (1H 2 L - 3H 2 L) and their complexes (1–3) were also evaluated for anti-tuberculosis activity against M. tuberculosis H37RV strain. It has been observed that with the increase of hydrophobicity of ligand due to substituent present at N1 atom, anti-TB activity increased (H, MIC = 6.25 µg/ml < Me, MIC = 3.12 µg/ml < Ph, MIC = 1.6 µg/ml). Molecular modeling studies have shown considerable intermolecular interaction of these compounds with minimum binding energy −5.8 (1H 2 L), −5.8 (2H 2 L), −9.6 (3H 2 L), −6.9 (1), −6.6 (2) and −9.6 (3) Kcal/ mol, which also supports the experimental data. Pharmacokinetics (effective transport of molecule to their target sites) was studied using drug-protein binding study of molecules with human serum albumin (HSA) was performed using UV–vis and fluorescence spectroscopy. The ligand 2H 2 L and complex 2 showed strong binding interactions with HSA having binding constant values of 4.24 × 105 M−1 and 4.92 × 105 M−1 respectively. N1-Substituted 2,5 thiophenedicarboxaldehyde bisthiosemicarbazones and their copper(II) complexes are synthesized and characterized using various spectroscopic techniques. All the compounds have shown good anti-tuberculosis activity against M. tuberculosis H37RV strain. Mode of interaction and their delivery to target site was studied using molecular docking and BSA binding studies. [Display omitted] [ABSTRACT FROM AUTHOR]

Metal-organic assemblies have received significant attention for catalytic and other applications, including gas and energy storage, due to their porosity and thermal/chemical stability. Here, we report the synthesis and physicochemical characterization of three metallosupramolecular assemblies consisting of isomeric ambidentate pyridyl-β-diketonate ligands L1–L3 and Cu(II) metal ions. It has been demonstrated that the topology and dimensionality of generated supramolecular aggregates depend on the location of the pyridine nitrogen donor atom in L1–L3. This is seen in characterization of two distinct 2D polymeric assemblies, i.e., [Cu(L1)2]n and [Cu(L2)2]n, in which both β-diketonate and pyridine groups are coordinated to the Cu(II) center, as well as in characterization of the mononuclear 1D complex Cu(L3)2, in which the central atom is bound only by two β-diketonate units.

Herein, we describe the synthesis and characterization of two novel tridentate ONN donor ligands, namely, (E)-2-(((2-(dimethylamino)ethyl)imino)methyl)-6-methoxyphenol ( HL 1 ) and (E)-2-(((2-(dimethylamino)ethyl)imino)methyl)-6-ethoxyphenol ( HL 2 ), and their copper(II) complexes, [Cu 2 (L 1 ) 2 (CH 3 COO) 2 ] ( 1 ), [Cu(L 2 )(CH 3 COO)]·2H 2 O ( 2 ). They have been synthesized under conventional methods and characterized by elemental analysis, FT-IR, 1 H NMR, 13 C NMR, ICP-OES, TGA, DSC and GC/MS analysis. For the morphological analysis field emission scanning electron microscopy (FESEM) was used. The geometry of the Cu(II) complexes was determined by single crystal X-ray diffraction analysis. The Cu(II) ions are in distorted square-pyramidal coordination environments. 1 crystallizes in orthorhombic space group, Pbca , while 2 crystallizes in monoclinic space group, P 2 1 / c . Effects of different solvents and concentrations on the photoluminescence properties of the 1 – 2 were investigated. The emission bands bathochromically shifted due to increase of the dipole moments of EtOH to H 2 O and CHCl 3 to DMSO, respectively. As a result of the dynamic quenching, the intensity of 1 was decreased with increasing the concentration in the water. The electrical conductivity complexes 1 – 2 have been also investigated. [ABSTRACT FROM AUTHOR]

The pesticide carbendazim (MBC) has nitrogen and oxygen in their structure which can interact with metal ions. This work evaluated the interaction between copper (II) ions with the pesticide carbendazim. The results obtained by cyclic voltammetry (CV) in 0.4 mol L−1 Britton-Robinson (BR) buffer (pH 4.0), under glass carbon electrode (GCE) to the MBC, showed an oxidation peak at 1.02 V and a reduction peak at 0.78 V vs Ag/AgCl, with characteristics of a quasi-reversible process controlled by the diffusion of the species in solution. For the Cu2+ metal ions, two reduction peaks were observed at − 0.26 and − 0.11 V and an oxidation peak at 0.04 V vs Ag/AgCl, with characteristics of a quasi-reversible process, controlled by the diffusion of the species in solution. In the interaction between carbendazim and copper metal ion, the formation of an oxidation peak around 0.60 V vs Ag/AgCl and a reduction peak around 0.08 V was observed, in a 1:1 ratio (Cu2+:MBC) in solution, suggesting that a new compound was formed. Complex formation was confirmed by UV-Vis spectroscopy, where changes were observed in the MBC absorption band and Cu2+ d-d band, suggesting the formation of a MBC-Cu complex. Analyses with the soil samples showed that after 30 min of the presence of the carbendazim solution in the soil, the pesticide had around 80% of its initial concentration adsorbed. When carbendazim is in the presence of the Cu2+ ion, about 62% of the pesticide is adsorbed, indicating that complexation influences adsorption of the species in the soil studied. [ABSTRACT FROM AUTHOR]

In the present study, we describe the synthesis and characterization of two tridentate N 2 O donor ligands, namely, (E)-2-(((2-(diethylamino)ethyl)imino)methyl)-6-methoxyphenol (HL 1 ) and (E)-2-(((2-(diethylamino)ethyl)imino)methyl)-6-ethoxyphenol (HL 2 ) , and their copper(II) complexes, [Cu(L 1 )(CH 3 COO)] (1) , [Cu(L 2 )(CH 3 COO)] (2) . They have been synthesized under conventional methods and characterized by elemental analysis, FTIR, 1 H and 13 C NMR, ICP-OES, TGA and GC/MS analysis. For the morphological analysis field emission scanning electron microscopy (FESEM) was used. The geometry of the copper(II) complexes was determined by single crystal X-ray diffraction analysis. The copper(II) ions are in distorted square-pyramidal coordination environments. Complexes crystallize in monoclinic space group, P 2 1 / c . The electrical conductivity and luminescence properties of 1 – 2 have been investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel stilbene-derivatized Schiff base ligands prepared for Cu(II) complexation. • Prepared in only three synthetic steps, from simple aromatic rings to complexes. • Ready to be studied as potential agents for PET imaging of β-amyloid plaques. Herein we present the synthesis and characterization of three Schiff base ligands derivatized with stilbene groups and their Cu(II) complexes CuL 1-3 , prepared in only three synthetic steps, from simple aromatic rings to complexes. The ligands L 1-3 were synthesized first by the C C coupling of an aryl bromide and styrene via a Heck reaction to produce a stilbene and then, by a condensation reaction between the stilbene and an aliphatic diamine to form tetradentate Schiff base ligands L 1-3. CuL 1-3 were then easily formed by complexation of Cu(II) ion in ethanolic media and obtained pure and in high yields. The complexes, ligands, and intermediates were fully characterized using FTIR, UV–vis, and NMR spectroscopy, as well as HRMS and XRD. These compounds exhibit two stilbene units, a functional group that has shown high affinity for amyloid plaques, an important biomarker of Alzheimer's disease. Thus, these compounds have the potential to be studied as radioimaging agents for the diagnosis of Alzheimer's by positron emission tomography (PET) when prepared with the positron-emitting radioisotope Cu-64. [ABSTRACT FROM AUTHOR]

This work describes the synthesis, anticancer activity and electron structure study of two Cu (II) complexes with coumarin-3-formyl-(3-(aminomethyl) pyridine) ligand (L) - C1 (Cu 2 L 2 (OAc) 4) and C2 (CuL 2 (NO 3) 2). The structure of C1 and C2 was confirmed by elemental analysis, FTIR, and single-crystal X-ray analysis. Complex C1 crystallizes as binuclear where two Cu (II) ions are bridged by four acetate ligands while C2 is a mononuclear complex with twisted octahedral geometry. Density functional theory (DFT) calculations revealed that electronic transitions originate from metal-ligand charge transfer and d - d transitions of metal ions. According to the results of UV–Vis and fluorescence titrations, C1 and C2 intercalate with DNA with the binding constants of 6.9 × 105 M−1 and 5.9 × 105 M−1, respectively. The in vitro cytotoxicity assays on four cancer cell lines (HeLa, HepG2, MCF-7 and A549) and a normal HUVEC cell line indicated higher anti-MCF-7 activity of C2 compared with cisplatin (IC 50 = 2.86 ± 0.08 μM vs. 9.07 ± 0.10 μM). Moreover, C2 had superior selectivity since IC 50 toward HUVEC cells was over 150 μM compared with 0.58 ± 0.05 μM for cisplatin. We concluded that the anti-MCF activity of mononuclear C2 complex is better than that of binuclear C1 and cisplatin. Therefore, C2 has been selected as a hit compound to develop novel non‑platinum anticancer agents through modification of coumarin-amide structure and variation of copper (II) salts. The anticancer activities, DNA interaction, and electron structure of Cu (II) complexes with coumarin-amide ligand (L)- C1 (Cu 2 L 2 (OAc) 4) and C2 (CuL 2 (NO 3) 2) were reported. C2 has been selected as a hit compound to develop novel non‑platinum anticancer agents because of its higher anti-MCF-7 activity and lower cytotoxicity than that of cisplatin. [Display omitted] • Two novel Cu (II) complexes (C1, C2) with coumarin-amide ligand were synthesized. • These complexes were characterized by single-crystal X-ray diffraction analysis. • The anti-MCF-7 activity of complex C2 is better than that of C1 and cisplatin. • Complexes C1 and C2 could effectively bind with DNA through intercalation mode. • DFT calculations of molecular orbitals and charge transfer were studied. [ABSTRACT FROM AUTHOR]

Four Schiff base copper (II) complexes derived from 1,3-bis(3-aminopropyl)tetramethyldisiloxane and 2-hydroxybenzaldehyde ( H 2 L 1 ), 3,5-di-bromo-2-hydroxybenzaldehyde ( H 2 L 2 ), 2-hydroxy-5-nitrobenzaldehyde ( H 2 L 3 ) and 5-chloro-2-hydroxybenzaldehyde ( H 2 L 4 ) were studied in terms of their biological and electrochemical application potentials. Thus, antimicrobial activity was evaluated against three fungi ( Aspergillus flavus ATCC 20046 , Penicillium chrysogenum ATCC 20044 , Alternaria alternate ATCC 8741 ) from pure culture and two bacteria species ( Pseudomonas aeruginosa ATCC 27813 and Bacillus sp . ATCC 31073 ). Among all the copper complexes investigated, the complex derived from 5-chlorosalicylaldehyde ( CuL 4 ) exhibit the highest biological activity. All the copper complexes have been investigated as possible active antioxidant enhancer for spirulina extract. Their redox behaviour was also investigated by running cyclic voltammetry measurements. [ABSTRACT FROM AUTHOR]

The coordinating properties in aqueous solution of two novel pyridine-4-methylene derivatives, diethyl(pyridine-4-ylmethyl)phosphate (4-PO(Oet)CH-py = 4-pmOpe) and 4-pyridylmethylphos phonic acid (4-PO(OH)CH-py = 4-pmpa), towards Cu(II) are compared with those of 4-hydroxymethyl-pyridine (4-OHCH-py = 4-pmOH). The two new derivatives were chosen due to their expected interesting biological activity that is observed for related solid complexes of several metals with various pyridine-methylene derivatives. The studies were carried out using pH potentiometry, UV-Vis spectrophotometry and EPR spectroscopy. The results show that 4-pmOpe and 4-pmpa, similarly to 4-OHCH-py, form mononuclear L:M = 1:1 and 2:1 complexes with Cu(II). However, in the case of 4-pmpa, complexation occurs both via oxygen atoms of the R- $$ {\text{PO}}_{3}^{2 - } $$ group (ML and ML species) and the N(1) nitrogen (protonated MLH and MLH complexes). The possible attendance of the third ligand in the coordination sphere was indicated for 4-OHCH-py by EPR spectroscopy. [ABSTRACT FROM AUTHOR]

A series of eight new copper (II) complexes of types [Cu(HL 1 )(B)] ( 4a – 4d ) and [Cu(HL 2 )(B)] ( 4e – 4h ), where HL 1 is N -(2-hydroxy-1-naphthalidene)-2-aminophenol, HL 2 is N -(2-hydroxy-1-naphthylidene)-2-mercaptoaniline and B is N, N donor ligands viz bipyridyl (bpy), 1,10-phenanthroline (phen), dipyridoquinoxaline (dpq) and dipyridophenazine (dppz) have been synthesized and characterized by elemental analysis as well as by spectroscopic techniques (IR, UV, ESI mass and EPR spectra). The DNA-binding properties of these copper complexes ( 4a – 4h ) have been investigated by electronic absorption, viscosity measurements and docking analyses. The results obtained indicated that the complexes get bonded with DNA via an intercalation binding mode with an intrinsic binding constant, K b (1.116 ± 0.21 to 7.227 ± 0.21) × 10 4 M −1 . The antimicrobial activity assays with the Schiff’s bases and their heteroleptic copper (II) complexes of 4a and 4b exhibited profound activity against gram positive bacteria, gram negative bacteria and fungi. Further, complexes 4d and 4h displayed significant cytotoxicity when examined in vitro on a panel of cancerous cell line – human liver cancer cell line – HepG-2 cells (IC 50 = 40.82 and 29.74 μg/ml). [ABSTRACT FROM AUTHOR]

The X-ray absorption fine structure (XAFS) spectra at the K-edge of the copper complexes Cu(PDC)(Mim) HO ( 1) and Cu(PDC)(EA)HO ( 2) (where PDC - Pyridine-2,3-dicarboxylic acid, Mim - 2-methylimidazole, and EA - ethyl acetate) have been investigated. The experimental extended X-ray absorption fine structure data of complex 1 have been analyzed by fitting the theoretical model generated from its own crystallographic data. The crystallographic data for complex 2 are not available. It has been found by comparing the intensity of the pre-edge peaks and X-ray absorption near edge structure features of complexes 1 and 2 that both complexes possess square pyramidal geometry around the copper centers and thus complex 2 is analogous to complex 1. Hence, the theoretical model generated for complex 1 has been fitted to the experimental EXAFS data of complex 2 to determine the structural parameters of complex 2. The coordination geometry of both complexes has been depicted. Further, the chemical shifts have been used to determine the oxidation state as well as to estimate the effective nuclear charge on the copper atom. [ABSTRACT FROM AUTHOR]

The new copper (II) complexes with substituted salicylaldehyde ligands (X-saloH, where X = 3-methoxy and 5-methyl) formulated as [Cu(3-OCH-salo)(HO)] ( 1) and [Cu(5-CH-salo)] ( 2), respectively, were synthesized and characterized by physicochemical methods and by spectroscopy (IR and UV-Vis). The different geometry around Cu ion for the two complexes was proved by single-crystal X-ray diffraction analysis. Simultaneous TG/DTG-DTA techniques were used to analyze their thermal behavior under inert atmosphere, with particular attention to determine their thermal degradation pathways, which was found to be a multi-step decomposition accompanied by the release of the ligand molecules. The activation energy of the decomposition processes was calculated using the isoconversional Ozawa-Flynn-Wall (OFW) method and the reaction model was determined with the model fitting method. [ABSTRACT FROM AUTHOR]

Reaction of hydrated copper (II) 2-iodobenzoate with β/γ-picoline in methanol:water mixture (4:1, v/v) yielded two rare aqua bridged zig-zag polymers [Cu(2-iodobenzoate) 2 (β-picoline) 2 (μ-H 2 O)] n ; 1 and [Cu(2-iodobenzoate) 2 (γ-picoline) 2 (μ-H 2 O)] n ; 2 . The newly synthesized complexes have been characterized by elemental analysis, FT-IR spectroscopy, UV–Vis spectroscopy and single crystal X-ray structure determination. Complex 1 crystallized in monoclinic crystal system with C2/c space group, and complex 2 crystallized in triclinic crystal system with P 1 ‾ space group. X-ray structure determination revealed the presence of 1-dimensional chains of constituent molecules running along a -axis in both complexes. Water molecules act as bridges between constituent molecules and hence play a crucial role in 1-dimensional chain propagation in zig-zag manner. Empty channels have been observed between the zig-zag chains of complexes. Non-covalent interactions interactions such as O–H⋯O, C–H⋯O and C–H⋯π have been observed, which play a decisive role in the stabilization of crystal lattices in both complexes 1 and 2 . [ABSTRACT FROM AUTHOR]

A new binuclear copper (I) complex, [Cu(Phterpy)2] (BF4)2(1), (Phterpy = 4′-phenyl-2,2′ : 6′, 2′-terpyridine), was synthesized. The interconversion to copper (II) complex [Cu(Phterpy)2] (BF4)2, from the reaction of [Cu(CH3CN)4]BF4with Phterpy in CH3CN, has been established. The new complex was characterized by IR, UV-Vis spectrum, and X-ray crystal structure analysis. The structural analysis shows each copper (I) in the complex 1 is six-coordinated in an octahedral geometry, adopting layered structure, respectively. UV-Vis absorption spectra changing with time and DFT calculations show that the copper complex in acetonitrile is [Cu(Phterpy)2] (BF4)2. [ABSTRACT FROM AUTHOR]

Highlights: [•] Design of new ligands (HL/L1) and copper (II) complexes. [•] Single crystal X-ray analysis. [•] Superoxide dismutase activity determination. [•] Magnetic susceptibility measurements. [•] Antimicrobial activity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Design of new ligand (L1H2) and their copper (II) complexes. [•] Single crystal X-ray analysis. [•] Superoxide dismutase activity determination. [•] Magnetic susceptibility measurements. [•] π…π interaction. [•] Antibacterial and Antifungal activity. [Copyright &y& Elsevier]

Highlights: [•] Three new zinc (II)–copper (II) heterotrinuclear complexes have been synthesized. [•] The structure of the ligand H4L2 has been established by X-ray crystallography. [•] The dihydrazone ligand is present in enol form in all of the complexes. [•] Copper centre has tetragonally distorted octahedral stereochemistry. [•] EPR parameters indicate that copper centre has doublet state as the ground state. [Copyright &y& Elsevier]

The cyclic voltammetric behaviour of copper (II) tetraethylethylenediamine systems with [Cu(II)]:[teen] =1:10, 1:100 molar ratios, 1x10-3M Cu(ClO4)2.6H2O in aqueous 0.2M NaClO4 supporting electrolyte have been studied at pH7.20, 9.10 and 10.85. The electrode process show quasi reversible one electron charge transfer preceded and followed by chemical reaction at glassy carbon electrode (GCE). For a given [Cu (II)]:[teen] molar ratio, Epc1 increases cathodically with pH. At a given pH, the value of Epc1 for 1:10 .1:100 indicating stability of complex species follow the same trend contrary to expectation. However, at a given metal: ligand ratio and at a given pH, Epc1 shifts anodically in the order en↓tmen↓teen, indicating that the ease of reduction also follows the same trend. [ABSTRACT FROM AUTHOR]

In this study, copper complexes with Curcumin (Cur) and 2,2'-bipyridine-5,5'-dicarboxylic acid (BPYD) were synthesized and their cytotoxicity on the MDA-MB-231 cell lines was evaluated. The resulting complex was characterized using FTIR, UV/VIS, CHNS, TGA, ICP-MS, and Mass spectroscopy techniques. The in-vitro cytotoxicity was studied on the MDA-MB-231 as a cancerous cell line and the HUVEC as a normal cell line. Reactive oxygen species (ROS) production was measured using the 2',7'-dichlorofluorescein diacetate (DCFDA) test in the MDA-MB-231 cancer cell lines. The in-vitro assays revealed that all synthesized copper complexes exhibited a higher cytotoxicity effect than carboplatin as a positive control on the MDA-MB-231 cells. While the synthesized complexes exhibited cytotoxic effects on cancerous cell lines, they are practically safe on normal cells. The Cu-Cur-BPYD complexes (a5 & b5) exhibited higher cytotoxicity on MDA-MB-231 cells with IC 50 s around 4.9 and 2.3 mM, respectively. It can be concluded that the synthesized Cu-Cur-BPYD complexes (a5 & b5) could be considered effective anticancer candidates in complementary studies., (© 2022 Wiley-VHCA AG, Zurich, Switzerland.)

Highlights: [•] Synthesis of 5-(arylazo)salicylaldehydes as preligands. [•] New tridentate Schiff base ligands were synthesized via condensation of preligand and 2-aminophenol or 2-aminothiophenol. [•] The new ligands were subjected to react with CuCl2. [•] The structures of the ligands and metals complexes were established. [ABSTRACT FROM AUTHOR]

Abstract: Mononuclear complexes [Cu(Itpy)X(H2O)]X (Itpy – imidazole terpyridine, X – NO3 1 and X – ClO4 2) have been synthesized and characterized. Single crystal X-ray diffraction of complex 1 shows distorted octahedral geometry around the copper (II) ion. Presence of multiple hydrogen bonding network in the molecule results in anti-parallel stacking of the molecule. Both the complexes show dual mode of binding to DNA. Both the complexes have been found to bring about DNA cleavage in the presence of H2O2 and show potent cytotoxicity towards lung carcinoma cell line. The ability of the two complexes to induce apoptosis has been investigated by using combination of nuclear stains. FACS analysis shows that both the complexes bring about cell cycle arrest at 2.5 μM concentration. [Copyright &y& Elsevier]

Abstract: A new tetradentate ligand N,N′-Bis (1-butyl-benzimidazol-2-yl-methyl)-hexane-1,6-dicarboxamide (b-GBSA) has been utilized to synthesize mononuclear copper (II) complexes with inner sphere anionic ligands like NO3 −, Br− and Cl−. Two of the complexes [Cu(L)NO3]NO3 (1) and [Cu(L)Br]Br (2) have been structurally characterized. The geometry of copper (II) in (1) is a distorted octahedral with NO3 − anion acting as a bidentate ligand, while for (2) the geometry is found to be a near square pyramidal. The complexes carry out the oxidation of substituted amino phenols in the presence of molecular oxygen. The oxidation gets blocked at the dihydrophenoxazinone stage for 2-amino-5-methyl phenol, and to o-quinone for 2-amino-4-tertiary butyl phenol, quite like the enzyme phenoxazinone synthase. [Copyright &y& Elsevier]

A new bipod polyaromatic acid ligand H 2bcm (H 2bcm = {2, 4-bis [(2′-carboxyphenoxy) methyl]-1,3,5-trimethylbenzene}) is prepared and its two novel binuclear coordination compounds, [Cu 2(bcm) 2(CH 3OH) 2]·2CH 3OH ( 1) and [Cu 2(bcm) 2(CH 3CH 2OH) 2]·2CH 3CH 2OH ( 2), have been synthesized with copper acetate and H 2bcm ligand in methanol solvent and ethanol solvent respectively, and characterized by the element analysis, IR, TGA and single crystal X-ray diffraction. The results of structural analysis indicate that 1 crystallizes in the triclinic system with space group P1, while 2 crystallizes in the monoclinic system with space group P2 1/c. Furthermore, 1 adopts μ2-COO − and syn– syn coordination mode with Cu (II)···Cu (II) separation of 2.5868(11) Å and forms 1D zigzag chain structure by O···O interactions. The coordination of 2 is similar to that of 1 except that ethanol molecules are coordinated instead of methanol molecules with Cu (II)···Cu (II) separation of 2.5973(13) Å. Two-dimensional network structures of 1 and 2 are formed through π–π interactions. Graphical Abstract: A new bipod polyaromatic acid ligand H 2bcm (H 2bcm= {2, 4-bis [(2′-carboxyphenoxy)methyl]-1,3,5-trimethylbenzene}) is prepared and its two novel binuclear coordination compounds, [Cu 2(bcm) 2(CH 3OH) 2]·2CH 3OH ( 1) and [Cu 2(bcm) 2(CH 3CH 2OH) 2]·2CH 3CH 2OH ( 2), have been synthesized with copper acetate and H 2bcm ligand in methanol solvent and ethanol solvent respectively, and characterized through single-crystal X-ray diffraction. Compound 1 crystallized in the space group P1, while 2 crystallizes in the monoclinic system with space group P2 1/c. Since the only difference in the synthetic condition between complexes 1 and 2 is that of the reaction solvent, resulting in the structure of complex 1 being significantly distinct from that of complex 2. It is clear that reaction solvent plays a key role in controlling the structure of the complexes.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Copper (II) complex of formulation [Cu-Phen-Tyr](HO)](ClO) (Phen = 1,10-phenanthroline, l-Tyr = l-tyrosine), has been prepared, and their induced DNA oxidative cleavage activity studied. The complex binds to DNA by intercalation, as deduced from the absorption and fluorescence spectral data. Scatchard plots constructed from the absorption titration data gave binding constant 2.44 × 10 M of base pairs. Extensive hypochromism, broadening, and red shifts in the absorption spectra were observed. Upon binding to DNA, the fluorescence from the DNA-ethidium bromide system was efficiently quenched by the copper (II) complex. Stern-Volmer quenching constant 0.61 × 10 M obtained from the linear quenching plots. [Cu-Phen-Tyr] complex efficiently cleave the supercoiled DNA to its nicked circular form with gallic acid as biological reductant at appropriate complex concentration. The gallic acid as reductant could observably improve copper (II) complex to DNA damage. The pseudo-Michaelis-Menten kinetic parameters ( k, K) were calculated to be 1.32 h and 5.46 × 10 M for [Cu-Phen-Tyr] complex. Mechanistic studies reveal the involvement of superoxide anions and hydroxyl radical (HO) as the reactive species under an aerobic medium. [ABSTRACT FROM AUTHOR]

Abstract: Novel copper (II)–N–(2-pyridyl)–N''–(5-R-salicylidene) hydrazine triphenylphosphine complexes have been synthesized and characterized. The complexes were effective in the catalytic oxidation of primary and secondary alcohols in presence of periodic acid (H5IO6) as oxidant. The oxidation reactions were carried out in acetonitrile. Electrochemical electron transfer study reveals CuII–CuI reduction in methanolic solutions. A mechanistic study of the above reactions has been proposed. [Copyright &y& Elsevier]

Abstract: A series of copper (II) complexes a – d with Schiff bases ligands derived from the condensation reactions between 2-pyridinecarboxaldehyde and different polyamines (ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine) were synthesized and characterized by elemental analysis, FT-IR spectroscopy, HRMS, molar conductance and molecular modeling studies. The interactions of the copper complexes a–d with DNA were investigated by the UV spectra, viscosity measurements and gel electrophoresis under physiological conditions. The experimental results indicated that four complexes could bind to DNA via an intercalative mode and showed a different DNA cleavage activity with the sequence: d > c > a > b . [ABSTRACT FROM AUTHOR]

The molecular and crystal structure of Cu(II) bischelate with the deprotonated stable nitroxide radical 4,4,5,5-tetramethyl-2-(2-oxo-1-(4,4,5,5-tetramethylimidazolidine-2-ylidene)ethyl)-4,5-dihydro-1 H-imidazole-3-oxide-1-oxylom (HL) are studied. It is revealed that the complex packing is formed of separate CuL2 molecules. Oxygen atoms in >N∸O groups do not participate in Cu2+ ion coordination, and so only weak exchange interactions are observed between paramagnetic centers in CuL2. [ABSTRACT FROM AUTHOR]

Abstract: A novel hexadentate nitrogen donor [N6] macrocyclic ligand, i.e. 2,6,12,16,21,22-hexaaza-3,5,13,15-tetramethyl-4,14-diethyl-tricyclo-[15.3.1.1(7-11)]docosane-1(21),2,5,7(22),8,10,12,15,17,19-decaene (L), has been synthesized. Copper(II) complexes with this ligand have been prepared and subjected to elemental analyses, molar conductance measurements, magnetic susceptibility measurements, mass, 1H NMR (ligand), IR, electronic, and EPR spectral studies. On the basis of molar conductance the complexes may be formulated as [Cu(L)X2] [X=Cl−, Br−, NO3 − and CH3COO−] due to their nonelectrolytic nature in N,N′-dimethylformamide (DMF). All the complexes are of the high spin type and are six coordinated. On the basis of IR, electronic and EPR spectral studies tetragonal geometry has been assigned to the Cu(II) complexes. The interaction of these complexes with calf thymus DNA has been explored by using absorption, emission, viscosity measurements, electrochemical studies and DNA cleavage. All the experimental results suggest that the complexes bind to DNA and also promote the cleavage plasmid pBR 322, in the presence of H2O2 and ascorbic acid. [Copyright &y& Elsevier]

Abstract: A series of the copper (II) complexes 5a–d of estrogen-macrocyclic polyamine conjugates were synthesized and characterized. The interactions of complexes 5a–d with DNA were studied by fluorescence spectroscopy and gel electrophoresis under physiological conditions. The results indicate that the conjugated estrogens have increased the cleavage efficiency of Cu[cyclen]2+ while the conjugates display poor binding affinities. The functional groups of D-ring of estrogens may play a key role in deciding binding and cleavage extent of the complexes to DNA. [Copyright &y& Elsevier]

Abstract: Mixed-ligand complexes of general formula, [Cu(NNS)(sac)] (NNS′= S-benzyl-β-N-(2-acetylpyrid-2-yl)methylenedithiocarbazate, NNS″= S-benzyl-β-N-(2-benzoylpyrid-2-yl)methylenedithiocarbazate and NNS‴= S-benzyl-β-N-(6-methylpyrid-2-yl)methylenedithio-carbazate, sac=the saccharinate anion) have been synthesized by reacting [Cu(sac)2(H2O)4]·2H2O with the appropriate ligands in ethanol and characterized by various physico-chemical techniques. Magnetic and spectral evidence indicate that the complexes are four-coordinate in which the Schiff bases coordinate as NNS ligands and the sac- anion coordinates as a unidentate N-donor ligand. An X-ray crystallographic structural analysis of [Cu(NNS′)(sac)] shows that the complex has a distorted square-planar geometry with the Schiff base coordinated to the copper (II) ion as a uninegatively charged tridentate chelating agent via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulphur atom while the fourth coordination position is occupied by the N-bonded saccharinate anion. The complexes have been evaluated for their biological activities against selected pathogens and cancer cell lines. They display weak activity against the pathogenic bacteria and fungi. The complexes were highly active against the leukemic cell line (HL-60) but only [Cu(NNS′)(sac)] was found to exhibit strong cytotoxicity against the ovarian cancer cell line (Caov-3). All complexes were inactive against the breast cancer cell line (MCF-7). [Copyright &y& Elsevier]

Abstract: Cu (II) complexes with 3,5-di(tert-butyl)-1,2-benzenediol (I), 4,6-di(tert-butyl)-1,2,3-benzentriol (II) and sulfur-containing sterically hindered o-diphenol derivatives such as 4,6-di(tert-butyl)-3-(2-hydroxyethylsulfanyl)-1,2-benzenediol (III) and 2-[4,6-di(tert-butyl)-2,3-dihydroxyphenylsulfanyl]acetic acid (IV) have been synthesized and characterized by means of elemental analysis, TG/DTA, FT-IR, ESR, XPS, XPD and conductivity measurements. Antifungal activities of these ligands and their respective Cu (II) complexes have been determined against Aspergillus niger, Fusarium sp., Penicillium lividum, Mucor sp. and Botrytis cinerea. Most of the compounds (both the free ligands and the complexes) exert pronounced antifungal activities (RI⩾70%), and virtually all of them (apart from the Cu(LII)2 complex) have the highest inhibitory properties (RI=100%) against B. cinerea. [Copyright &y& Elsevier]

Abstract: Cu(II) complexes with 4,6-di(tert-butyl)-2-aminophenol (I) and 2-anilino-4,6-di(tert-butyl)phenol (II) have been synthesized and characterized by means of elemental analysis, TG/DTA, FT-IR, UV–vis, ESR, and conductance measurements. The compounds I and II can coordinate in their singly deprotonated forms and behave as bidentate O,N-coordinated ligands; their CuL2 complexes are characterized by CuN2O2 coordination modes and square planar geometry. In vitro antimicrobial screening against Gram-positive and Gram-negative bacteria, yeasts, and moulds indicated that the compound I and its Cu(II) complex were more active than Questiomycin B, the compound II, and its Cu(II) complex. [Copyright &y& Elsevier]

Abstract: Series of activated-carbon fibers-supported copper (II) complex catalysts (Cu/ACF) were prepared to catalyze the reaction of methanol to methyl formate (MF). The ligands used for the preparation of copper complexes include ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, 1,4-diaminobutane and 1,6-diaminohexane. The activities of all Cu/ACF catalysts increase with the ratio of ligand/Cu, passes through a maximum, and then decrease. The catalysts having the optimum results of methanol conversion and MF yield show different values of ligand/Cu, but show a similar UV–Vis absorption band around 700nm. The catalytic activity of catalyst can be adjusted by the selection and the varying of the coordination number of the ligands. The slightly reduced Cu (II) species having an absorption band around 700nm were found to be the effective sites. [Copyright &y& Elsevier]