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A crystalline dihydroxy substituted Schiff base ligand [LH] was involved in the synthesis of three copper(II) complexes viz [Cu(LH)2] (Cu1), [Cu(LH)(bpy)] (Cu2) and [Cu(LH)(phen)] (Cu3) (bpy=2,2'‐bipyridine and phen=1,10‐phenanthroline). FTIR, ESI‐MS, elemental analysis, ESR studies and NMR techniques were employed to characterize all the newly synthesized compounds. Monoclinic structure with space group P21/n of ligand (LH) was confirmed by single crystal XRD analysis. The molecular structure of ligand and complexes were optimized using density functional theory (DFT) at B3LYP/LanL2DZ levels in the gas phase. According to DFT investigations Cu1 exhibits tetragonally distorted octahedral geometry around Cu(II) while Cu2 and Cu3 appeared in penta‐coordination as distorted trigonal bipyramidal geometry. UV‐Vis, fluorescence and viscosity titrations were used to examine the metal complex interactions with CT‐DNA and BSA protein. The binding results suggest that the complexes bind to DNA via groove binding mode. Molecular docking was performed to analyse the binding interaction of complexes with BSA and DNA. Antioxidant investigation indicates that the Cu1 possesses remarkable ability to scavenge radicals against DPPH due to the lowest IC50 value 211.20 μg/mL. In‐vitro cytotoxicity was assessed against MCF‐7 breast cancer cells where Cu1 was found to have superiority in cytotoxicity with IC50 value 52.35 μm over other analogues. Acridine orange/ethidium bromide staining analysis of Cu1 were used to determine apoptosis as the cause of cell death. [ABSTRACT FROM AUTHOR]

Bis(macrocyclic) complexes are investigated as artificial analogues of natural dinuclear metalloenzymes. Two ligands containing two cyclam rings connected through a p‐cresol or 4‐nitrophenol spacer were synthesized and their complexing properties were investigated. CuII complexes were prepared and their properties were studied by a combination of spectral, diffraction and electrochemical methods. The phenolate group is not or only weakly coordinated to the central CuII ion and the two macrocycles behave mostly as two independent complexing units. All the determined solid‐state structures showed cyclam adopting trans‐III geometry, however, solution study indicated the presence of more isomers in the solution whose abundance changes with pH. Electrochemical reduction of the complexes is irreversible and results in the reductive decomplexation to amalgamated Cu metal. The amalgamated metal is re‐oxidized to CuII during the anodic scan of CV and the metal ion is re‐coordinated. The ligand containing the nitro group shows an irreversible four‐electron reduction of the nitro group. The ligands and the complexes undergo also a slow degradation when incubated in the aqueous solutions for a prolonged time. The degradation relies on the "retro‐Mannich" cleavage of the methylene bridge connecting the cyclam ring with the phenol moiety. [ABSTRACT FROM AUTHOR]

Research in the field of metallodrugs is continually increasing. However, it is often limited by the poor solubility in water of the metal complexes. To try to overcome this problem, the two new ligands bis-(sodium 3-methoxy-5-sulfonate-salicylaldehyde)thiocarbohydrazone (bis-TCH, Na2H4L1) and bis-(sodium 3-methoxy-5-sulfonate-salicylaldehyde)carbohydrazone (bis-CH, Na2H4L2) were synthesized and characterized, both achieving high solubility in water. The speciation of the ligands and their coordinating behaviour towards the biologically relevant Cu(II) and Zn(II) ions were studied spectroscopically and potentiometrically, determining the pKas of the ligands and the formation constants of the complex species. The monometallic and bimetallic Cu(II) and Zn(II) complexes were isolated, and the single-crystal X-ray structure of [Cu2(NaHL1)(H2O)7].3.5H2O was discussed. Finally, preliminary studies of the in vitro cytotoxic properties of the new compounds were started on normal (Hs27) and cancer (U937) cell lines. bis-TCH was able to induce a growth inhibition effect between 40% and 45% in both cell lines; bis-CH did not produce a reduction in cell viability in Hs27 cells but revealed mild antiproliferative activity after 72 h of treatment in U937 cancer cells (GI50 = 46.5 ± 4.94 μg/mL). Coordination of the Cu(II) ions increased the toxicity of the compounds, while, in contrast, Zn(II) complexes were not cytotoxic. [ABSTRACT FROM AUTHOR]

In this study five different complexes of Cu(II) were synthesized for the purpose of environmentally notorious mercury sensing and preliminary biological screening. Pyridine‐2,6‐dicarboxylic acid (also known as dipicolinic acid, and abbreviated as H2DPA), 3‐phenyl pyrazole (3‐ppz), 4‐iodo‐1H‐pyrazole (4‐ipz), 4‐nitropyrazole (4‐npz), 4‐bromopyrazole (4‐bpz), and 4‐chloropyrazole (4‐cpz) were chosen as potential ligands. The synthesized complexes labelled as 1–5, namely [Cu(DPA)(3‐ppz)], [Cu(DPA)(4‐ipz)], [Cu(DPA)(4‐npz)], [Cu(DPA)(4‐bpz)], [Cu(DPA)(4‐cpz)], were proposed based on spectroscopic data (FTIR, TGA, and UV‐visible spectroscopy). These complexes feature C=O functionalities that are not involved in coordination and may be used for further applications. The isolated complexes were utilized for detecting Hg(II) ions in water samples. Various concentrations of Hg(II) ions were prepared for detection purposes, and changes in absorption concerning complexes 1–5 were determined using UV‐Visible spectroscopy. It was found that complexes 3 and 4 exhibit efficient sensing abilities towards Hg(II) ions. The antibacterial activities of complexes 1–5 were assessed against S. typhi and E. coli. The complexes 1 and 3 displayed good antibacterial activities against S. typhi (13.67, and 13.56 mm, respectively) while complexes 1, 2 and 4 were found to be efficient against E. coli (11.6, 12.66, 11.31 mm, respectively). The absorption maxima of 2,2‐diphenyl‐1‐picryhydrazyl (DPPH) at 517 nm, considerably shifted upon addition of complexes 1–5. The results reveal that the complexes possess potential free radical scavenging abilities. [ABSTRACT FROM AUTHOR]

Copper(II) chloride anionic coordination complexes with different imidazole‐derived ligands due to the potential cytotoxic activity play the important role in protein. By investigating the experimental electron paramagnetic resonance (EPR) and ultraviolet–visible (UV–vis) spectra of [CuCl(C6H10N2)4]Cl, [CuCl(C6H10N2)4]Cl, [CuCl2(C4H6N2)4], and [Cu2Cl2(C5H8N2)6]Cl2·2H2O, the local structure of the corresponding Cu2+ centers and the role of different ligands are obtained. Based on the well‐agreed EPR parameters and the d‐d transitions (10Dq), the four Cu2+ centers show tetragonal and orthorhombic distortion, corresponding to the different anisotropies of EPR signals. In addition, the general rules of governing the impact of methanol in imidazolylalkyl derivatives are also discussed, especially the influence on the local environment (symmetry, distortion, covalency, and crystal field) of above four copper(II) chloride anionic coordination complexes. Therefore, the obtained results in this study will be beneficial to provide a theoretical basis for the experimental design of desired copper‐containing imidazolyl alkyl derivatives. [ABSTRACT FROM AUTHOR]

We have synthesized and characterized five copper(II) complexes, [Cu(L1)(alanine)(NO3)]·2H2O (1), [Cu(L1)(methionine)(H2O)]NO3·4H2O (2), [Cu(L2)(glycine)] NO3·3H2O (3), [Cu(L2)(alanine)Cl]·2H2O (4) and [Cu(L3)(phenylalanine)Br] (5), (L1 = 3-(1H-imidazo[4,5-f][1, 10]phenanthrolin-2-yl)phenol; L2 = 2-(4-fluorophenyl)-1Himidazo[4,5-f][1, 10]phenanthroline; L3 = 4-(1H-imidazo[4,5-f][1, 10]phenanthrolin-2-yl)phenol). Antiproliferative activity was examined using MTT assay against seven human cancer cells. Complexes 1 and 3 induced apoptosis in MDA-MB-231 cells. We also have investigated the potential anti-stemness properties in which the proportion of breast cancer stem cells in MDA-MB-231 cells (CD44 + CD24– cell subpopulation) were significantly reduced by 1 and 3. Furthermore, they decrease the size and mammospheres formed, inhibit tumor cell migration, and reverse epithelial–mesenchymal transition progression, as well as induce a reduction in expression of stemness markers, Nanog, and Sox-2 proteins. The copper(II) complexes may possess potential in treating TNBC with stem cell-like properties. [ABSTRACT FROM AUTHOR]

New Cu(II) complexes with pyridoxal-aminoguanidine (PLAG) ligands and different counterions (SO42− and NO3−) were prepared and their crystal structures were solved by the X-ray crystallography. The geometries of the obtained complexes significantly depended on the counterions, leading to the square-pyramidal structure of [Cu(PLAG)NO3H2O]NO3 (complex 1) and square-planar structure of [Cu(PLAG)H2O]SO4 (complex 2). The intermolecular interactions were examined using the Hirshfeld surface analysis. The theoretical structures of these complexes were obtained by optimization at the B3LYP/6-311++G(d,p)(H,C,N,O,S)/LanL2DZ(Cu) level of theory. The Quantum Theory of Atoms in Molecules (QTAIM) was applied to assess the strength and type of the intramolecular interactions and the overall stability of the structures. The interactions between the complexes and transport proteins (human serum albumin (HSA)) and calf thymus DNA (CT-DNA) were examined by spectrofluorometric/spectrophotometric titration and molecular docking. The binding mechanism to DNA was assessed by potassium iodide quenching experiments. The importance of counterions for binding was shown by comparing the experimental and theoretical results and the examination of binding at the molecular level. [ABSTRACT FROM AUTHOR]

A series of edaravone derivatives and the corresponding Cu(II) complexes were synthesized and characterized using spectroscopic and analytical techniques such as IR, UV, NMR and elemental analysis. Antioxidant activities of all compounds were examined using free radical scavenging methods such as hydrogen peroxide scavenging activity (HPSA), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2-2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) assays. All of the tested compounds exhibited good antioxidant activity. Further, the frontier orbital energy levels, as well as various chemical properties, were determined using the density functional theory (DFT) calculations. The MEP maps of all of the derivatives were plotted to identify the nucleophilic and electrophilic reactive sites. Further, binding energies of all of the organic compounds with the protein tyrosinase was investigated to determine their potential anti-melanogenic applications. The selected ligand, L6 was subjected to molecular dynamics simulation analysis to determine the stability of the ligand–protein complex. The MD simulation was performed (150 ns) to estimate the stability of the tyrosinase–L6 complex. Other key parameters, such as, RMSD, RMSF, Rg, hydrogen bonds, SASA and MMPBSA were also analyzed to understand the interaction of L6 with the tyrosinase protein. [ABSTRACT FROM AUTHOR]

A number of new copper(II) complexes of 2-(N-tosylamino)benzaldehyde benzoylhydrazone (H2L) CuLLn (n = 1–6) with heterocyclic donor ligands (L1 = 1-propyl-2-aminobenzimidazole, L2 = 1‑hexyl-2-aminobenzimidazole, L3 = 1-octyl-2-aminobenzimidazole, L4 = 2,2'-bipyridine, L5 = 1,10-phenanthroline, and L6 = 2-aminopyridine) is synthesized. The structures and compositions of the synthesized compounds are determined by elemental analysis, 1Н NMR spectroscopy, IR spectroscopy, and magnetochemistry. The molecular structures of complexes CuLL1,2,4−6 are determined by XRD (CIF files CCDC nos. 2341480 (CuLL1), 2341468 (CuLL2), 2341478 (CuLL4), 2341477 (CuLL5), and 2341479 (CuLL6)). The biological activity of the complexes is studied. The adducts with L1, L2, and L6 exhibit a significantly higher anti-protist activity than chloroquine used as the reference compound. [ABSTRACT FROM AUTHOR]

The goal of this study is to synthesize, determine the structure, and examine the antimicrobial properties of novel Cu(II) and Au(III) complexes of 2,4-dithiouracil and its derivatives. These complexes were obtained by mixing aqueous solutions of the corresponding metal salts with the ligand dissolved in DMSO and aqueous NaOH, using a metal-to-ligand ratio of 1:4:2. The structures of the new compounds were analyzed by melting point determination, microwave plasma atomic emission spectrometry (MP-AES) for Cu and Au, inductively coupled plasma optical emission spectrometry (ICP-OES) for S, attenuated total reflection (ATR), solution and solid-state NMR, and Raman spectroscopy. The data for 2,4-dithiouracil obtained from the 1H NMR, 13C NMR, distortionless enhancement by polarization transfer spectrum (DEPT-135), proton–proton homonuclear correlation spectrum (1H-1H COSY), long-range 1H-13C heteronuclear multiple bond correlation experiment (HMBC), and heteronuclear single quantum coherence spectra (HSQC) aided the interpretation of the NMR data for the gold and copper complexes. Furthermore, the antimicrobial effect of the free ligands and their complexes was assessed against Gram-positive and Gram-negative bacteria, as well as yeasts. [ABSTRACT FROM AUTHOR]

The following series of copper(II) complexes based on di(o-tolyl)phosphinic acid (HL) and 1,10-phenanthroline (phen), 5-chloro-1,10-phenanthroline (Cl-phen), 4,7-dimethyl-1,10-phenanthroline (dmphen), 2,2′-bipyridine (bipy) is prepared and characterized: [Cu(OH)L]n (1), [Cu(phen)(H2O)L2] (2), [Cu(dmphen)(H2O)L2] (3), [Cu(Cl-phen)(H2O)L2] (4), [Cu(bipy)(H2O)L2] (5). According to the XRD data, the phosphinate anion L– exhibits a monodentate coordination in mononuclear complexes 2–5 and a bidentate-bridge coordination in the polymer complex 1. The cytotoxic activity of the ligands and complexes is studied using the A549 (carcinoma) and MRC5 (non-neoplastic fibroblasts) human lung cell lines. It is shown that the complexes exhibit pronounced dose-dependent cytotoxicity to these cell lines in the 1-50 µM concentration range. [ABSTRACT FROM AUTHOR]

A novel copper(II) complex based on N-2-(2-pyridyl)ethyl-2-aminoethanesulfonic acid is prepared, its structure is studied by XRD (CCDC No. 2215117). The crystal of the complex is formed by monomeric [CuLH2O]NO3 units. The metal centers of the units have an octahedral coordination environment formed by nitrogen atoms of pyridine and the amino group, oxygen atoms of the sulfo group, and water molecules located in the equatorial plane. On the axial axis, there are oxygen atoms of the sulfo groups of the neighboring ligands forming a 1D coordination polymer. [ABSTRACT FROM AUTHOR]

The catalytic properties of three copper complexes, [Cu(en)2](ClO4)2 (1), [Cu(amp)2](ClO4)2, (2) and [Cu(bpy)2](ClO4)2 (3) (where en = ethylenediamine, amp = 2-aminomethylpyridine and bpy = 2,2′-bipyridine), were explored upon the oxidation of benzyl alcohol (BnOH). Maximized conversions of the substrates to their respective products were obtained using a multivariate analysis approach, a powerful tool that allowed multiple variables to be optimized simultaneously, thus creating a more economical, fast and effective technique. Considering the studies in a fluid solution (homogeneous), all complexes strongly depended on the amount of the oxidizing agent (H2O2), followed by the catalyst load. In contrast, time seemed to be statistically less relevant for complexes 1 and 3 and not relevant for 2. All complexes showed high selectivity in their optimized conditions, and only benzaldehyde (BA) was obtained as a viable product. Quantitatively, the catalytic activity observed was 3 > 2 > 1, which is related to the π-acceptor character of the ligands employed in the study. Density functional theory (DFT) studies could corroborate this feature by correlating the geometric index for square pyramid Cu(II)-OOH species, which should be generated in the solution during the catalytic process. Complex 3 was successfully immobilized in silica-coated magnetic nanoparticles (Fe3O4@SiO2), and its oxidative activity was evaluated through heterogenous catalysis assays. Substrate conversion promoted by 3-Fe3O4@SiO2 generated only BA as a viable product, and the supported catalyst's recyclability was proven. Reduced catalytic conversions in the presence of the radical scavenger (2,2,6,6-tetrametil-piperidi-1-nil)oxil (TEMPO) indicate that radical and non-radical mechanisms are involved. [ABSTRACT FROM AUTHOR]

Abstract In this study five different complexes of Cu(II) were synthesized for the purpose of environmentally notorious mercury sensing and preliminary biological screening. Pyridine‐2,6‐dicarboxylic acid (also known as dipicolinic acid, and abbreviated as H2DPA), 3‐phenyl pyrazole (3‐ppz), 4‐iodo‐1H‐pyrazole (4‐ipz), 4‐nitropyrazole (4‐npz), 4‐bromopyrazole (4‐bpz), and 4‐chloropyrazole (4‐cpz) were chosen as potential ligands. The synthesized complexes labelled as 1–5, namely [Cu(DPA)(3‐ppz)], [Cu(DPA)(4‐ipz)], [Cu(DPA)(4‐npz)], [Cu(DPA)(4‐bpz)], [Cu(DPA)(4‐cpz)], were proposed based on spectroscopic data (FTIR, TGA, and UV‐visible spectroscopy). These complexes feature C=O functionalities that are not involved in coordination and may be used for further applications. The isolated complexes were utilized for detecting Hg(II) ions in water samples. Various concentrations of Hg(II) ions were prepared for detection purposes, and changes in absorption concerning complexes 1–5 were determined using UV‐Visible spectroscopy. It was found that complexes 3 and 4 exhibit efficient sensing abilities towards Hg(II) ions. The antibacterial activities of complexes 1–5 were assessed against S. typhi and E. coli. The complexes 1 and 3 displayed good antibacterial activities against S. typhi (13.67, and 13.56 mm, respectively) while complexes 1, 2 and 4 were found to be efficient against E. coli (11.6, 12.66, 11.31 mm, respectively). The absorption maxima of 2,2‐diphenyl‐1‐picryhydrazyl (DPPH) at 517 nm, considerably shifted upon addition of complexes 1–5. The results reveal that the complexes possess potential free radical scavenging abilities.

Metal complexes, which, under physiologic conditions, show redox properties and are able to bind to DNA, are great tools to cleave the DNA chain. This aspect is of great importance for their use as antineoplastic drugs. We synthesized ligands derived from short-chain amino acids and from salicylaldehyde. The prepared ligands of the type of reduced Schiff bases were subsequently used for the preparation of copper(II) complexes. The aim of the study was in vitro testing of copper(II) complexes, where it was confirmed that they are capable of cleaving DNA. Their cytotoxic activity was also confirmed by the resazurin redox method on Saccharomyces cerevisiae based on preserved healthy mitochondrial function.

Detailed electrochemical study of copper(II) complexes of cyclam bearing two phosphonate (TE2P), phenolate (TE2PhOH) or carboxylate (TE2A) pendant arms (together with one cross‐bridged‐cyclam derivative cb‐TE2A) was performed using cyclic voltammetry (CV) and polarography. The electrochemical‐heterogeneous measurements were accompanied by UV‐vis spectra describing the situation in homogeneous phase. Reduction of complexes on mercury electrode in buffered aqueous solutions (pH 2–12) occurs generally as a two‐electron process of reductive decomposition. The formed Cu‐amalgam can be (e. g. during the anodic scan of CV) reoxidized to Cu(II) cation which undergoes re‐complexation resulting in the original complex. This process of a square diagram is manifold repeatable. The results also showed presence of several isomers differing in mutual orientation of substituents on cyclam nitrogen atoms. The primary "kinetic", pentacoordinated isomers are irreversibly transformed to the stable, hexacoordinated "thermodynamic" ones upon heating. The development of isomerization process was followed electrochemically. The cross‐bridged cb‐TE2A derivative forms only one isomer which does not change even after heating. The higher stability of the complex manifests itself at pH>8 when the complex is reversibly reduced in one‐electron step, formally CuII/CuI, without decomposition. [ABSTRACT FROM AUTHOR]

A series of edaravone derivatives and the corresponding Cu(II) complexes were synthesized and characterized using spectroscopic and analytical techniques such as IR, UV, NMR and elemental analysis. Antioxidant activities of all compounds were examined using free radical scavenging methods such as hydrogen peroxide scavenging activity (HPSA), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2-2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) assays. All of the tested compounds exhibited good antioxidant activity. Further, the frontier orbital energy levels, as well as various chemical properties, were determined using the density functional theory (DFT) calculations. The MEP maps of all of the derivatives were plotted to identify the nucleophilic and electrophilic reactive sites. Further, binding energies of all of the organic compounds with the protein tyrosinase was investigated to determine their potential anti-melanogenic applications. The selected ligand, L6 was subjected to molecular dynamics simulation analysis to determine the stability of the ligand–protein complex. The MD simulation was performed (150 ns) to estimate the stability of the tyrosinase–L6 complex. Other key parameters, such as, RMSD, RMSF, Rg, hydrogen bonds, SASA and MMPBSA were also analyzed to understand the interaction of L6 with the tyrosinase protein.

New Cu(II) complexes with pyridoxal-aminoguanidine (PLAG) ligands and different counterions (SO42− and NO3−) were prepared and their crystal structures were solved by the X-ray crystallography. The geometries of the obtained complexes significantly depended on the counterions, leading to the square-pyramidal structure of [Cu(PLAG)NO3H2O]NO3 (complex 1) and square-planar structure of [Cu(PLAG)H2O]SO4 (complex 2). The intermolecular interactions were examined using the Hirshfeld surface analysis. The theoretical structures of these complexes were obtained by optimization at the B3LYP/6-311++G(d,p)(H,C,N,O,S)/LanL2DZ(Cu) level of theory. The Quantum Theory of Atoms in Molecules (QTAIM) was applied to assess the strength and type of the intramolecular interactions and the overall stability of the structures. The interactions between the complexes and transport proteins (human serum albumin (HSA)) and calf thymus DNA (CT-DNA) were examined by spectrofluorometric/spectrophotometric titration and molecular docking. The binding mechanism to DNA was assessed by potassium iodide quenching experiments. The importance of counterions for binding was shown by comparing the experimental and theoretical results and the examination of binding at the molecular level.

Four copper(II) complexes, C1–4, derived from 1-(isoquinolin-3-yl)heteroalkyl-2-one ligands L1–4 were synthesized and characterized using an elemental analysis, IR spectroscopic data as well as single crystal X-ray diffraction data for complex C1. The stability of complexes C1–4 under conditions mimicking the physiological environment was estimated using UV-Vis spectrophotometry. The antiproliferative activity of both ligands L1–4 and copper(II) compounds C1–4 were evaluated using an MTT assay on four human cancer cell lines, A375 (melanoma), HepG2 (hepatoma), LS-180 (colon cancer) and T98G (glioblastoma), and a non-cancerous cell line, CCD-1059Sk (human normal skin fibroblasts). Complexes C1–4 showed greater potency against HepG2, LS180 and T98G cancer cell lines than etoposide (IC50 = 5.04–14.89 μg/mL vs. IC50 = 43.21–>100 μg/mL), while free ligands L1–4 remained inactive in all cell lines. The prominent copper(II) compound C2 appeared to be more selective towards cancer cells compared with normal cells than compounds C1, C3 and C4. The treatment of HepG2 and T98G cells with complex C2 resulted in sub-G1 and G2/M cell cycle arrest, respectively, which was accompanied by DNA degradation. Moreover, the non-cytotoxic doses of C2 synergistically enhanced the cytotoxic effects of chemotherapeutic drugs, including etoposide, 5-fluorouracil and temozolomide, in HepG2 and T98G cells. The antimicrobial activities of ligands L2–4 and their copper(II) complexes C2–4 were evaluated using different types of Gram-positive bacteria, Gram-negative bacteria and yeast species. No correlation was found between the results of the antiproliferative and antimicrobial experiments. The antioxidant activities of all compounds were determined using the DPPH and ABTS radical scavenging methods. Antiradical tests revealed that among the investigated compounds, copper(II) complex C4 possessed the strongest antioxidant properties. Finally, the ADME technique was used to determine the physicochemical and drug-likeness properties of the obtained complexes. [ABSTRACT FROM AUTHOR]

CuII ternary systems with aromatic N‐donors (1,10‐phenanthroline, dipyrido‐[3,2‐f:2',3'‐h]‐quinoxaline, and 2‐methyldipyrido‐[3,2‐f:2',3'‐h]‐quinoxaline) and amino acids have been extensively studied in water solution under closely physiological conditions using several techniques, including potentiometric pH titration, mathematical modeling, nuclear magnetic relaxation, EPR, and DFT calculations. Based on the distribution diagrams of the complex species, single crystal syntheses of the ternary systems CuII‐aromatic N‐donor‐L‐amino acid were carried out. As a result, several crystal structures of the complexes with the desired copper‐to‐ligand ratio were established by X‐ray diffraction analysis. The most successful synthetic attempts were with L‐proline and L‐serine, resulting in the crystals with the desired copper(II) to ligand ratio. The developed approach made it possible to thoroughly describe systems with major proteinogenic amino acids in the L‐configuration. Numerous non‐covalent interactions such as H‐bonds, π‐π stacking, d‐π interactions, lone electron pair‐π interactions between CuII atom, conjugated aromatic ligand system, counterions, and water molecules were found to affect the stability and structure of the resulting complex particles. It has been found that in the CuII–N‐donor–amino acid systems there is an acceleration of ligand exchange by a factor of 2–25 compared to CuII‐amino acid systems, which is explained by taking into account steric effects, d‐π interactions, and the pseudo Jahn‐Teller effect. The investigated systems were tested for antitumor activity against MCF‐7, PC‐3, OVCAR‐4, SNB‐19, and M‐14 cell lines, and most samples, in particular, CuII–Phen–L‐His, CuII–MeDPQ−L‐Val and CuII–MeDPQ−L‐Ser, showed a therapeutic activity index greater than 2 for all selected cell types, which opens up prospects for their medical application. [ABSTRACT FROM AUTHOR]

Metal complexes, which, under physiologic conditions, show redox properties and are able to bind to DNA, are great tools to cleave the DNA chain. This aspect is of great importance for their use as antineoplastic drugs. We synthesized ligands derived from short-chain amino acids and from salicylaldehyde. The prepared ligands of the type of reduced Schiff bases were subsequently used for the preparation of copper(II) complexes. The aim of the study was in vitro testing of copper(II) complexes, where it was confirmed that they are capable of cleaving DNA. Their cytotoxic activity was also confirmed by the resazurin redox method on Saccharomyces cerevisiae based on preserved healthy mitochondrial function. [ABSTRACT FROM AUTHOR]

The aim of the present study is to synthesize new metal complexes of 6-methyl-2-thiouracil and 6-propyl-2-thiouracil, elucidate their structures, and investigate their biological properties. All metal complexes were obtained after mixing water solutions of the corresponding metal salts and the ligand dissolved in DMSO and water solutions of NaOH in a metal-to-ligand ratio of 1:4:2. The structures of the new compounds are discussed based on melting point analysis (MP-AES) for Cu and Pd, UV-Vis, IR, ATR, 1H NMR, 13C NMR, and Raman spectroscopy. The interpretation of complex spectra is assisted by the data for 6-methyl-2-thiouracil and 6-propyl-2-thiouracil obtained from 1H-1H COSY, DEPT-135, HMBC and HMQC spectra. In addition, the antimicrobial activity of these complexes and the free ligands are assessed against both Gram-positive and Gram-negative bacteria, as well as yeasts. In general, the addition of metal ions improved the antimicrobial activity of both 6-methyl-2-thiouracil and 6-propyl-2-thiouracil. The Cu(II) complex with 6-methyl-2-thiouracil and the Pd(II) complex with 6-propyl-2-thiouracil exhibited the highest activity against the test microorganisms. [ABSTRACT FROM AUTHOR]

Syntheses, characterization, and physical properties of two complexes of copper(II) having the general molecular formula [Cu(Ln)2] (1 and 2) with benzyl-N′-(4-R-benzoyl)-N-(2,6-diisopropylphenyl)carbamimidothioates (HLn, where n = 1 and 2 for R = H and Cl, respectively) are reported. Both complexes were characterized by mass spectrometric, magnetic susceptibility, and various spectroscopic (IR, UV–Vis, and EPR) measurements. The molecular structures of 1 and 2 were established by single crystal X-ray crystallographic studies. In each complex, the bivalent metal center is in a near perfect square-planar trans-N2O2 coordination environment assembled by two bidentate six-membered chelate rings forming iminolate-O and azomethine-N donor (Ln)− ligands. In the crystal lattice, the packing of 1 is according to the symmetry operations, while intermolecular π⋯π and C–H⋯π interactions assisted self-assembly of 2 leads to a two-dimensional sheet-like structure. Mass spectrometric and infrared and electronic spectroscopic data are in agreement with their molecular formulas and similar structures. The room temperature magnetic moments and EPR spectra of both complexes are consistent with the S = ½ ground state and the square-planar coordination geometry of the metal ion in each complex. [ABSTRACT FROM AUTHOR]

Abstract Detailed electrochemical study of copper(II) complexes of cyclam bearing two phosphonate (TE2P), phenolate (TE2PhOH) or carboxylate (TE2A) pendant arms (together with one cross‐bridged‐cyclam derivative cb‐TE2A) was performed using cyclic voltammetry (CV) and polarography. The electrochemical‐heterogeneous measurements were accompanied by UV‐vis spectra describing the situation in homogeneous phase. Reduction of complexes on mercury electrode in buffered aqueous solutions (pH 2–12) occurs generally as a two‐electron process of reductive decomposition. The formed Cu‐amalgam can be (e. g. during the anodic scan of CV) reoxidized to Cu(II) cation which undergoes re‐complexation resulting in the original complex. This process of a square diagram is manifold repeatable. The results also showed presence of several isomers differing in mutual orientation of substituents on cyclam nitrogen atoms. The primary “kinetic”, pentacoordinated isomers are irreversibly transformed to the stable, hexacoordinated “thermodynamic” ones upon heating. The development of isomerization process was followed electrochemically. The cross‐bridged cb‐TE2A derivative forms only one isomer which does not change even after heating. The higher stability of the complex manifests itself at pH>8 when the complex is reversibly reduced in one‐electron step, formally CuII/CuI, without decomposition.

A mononuclear square-planar CuII complex of (5-methyl-1H-pyrazol-3-yl)carbamate, [Cu(C5H6N3O2)2]·4H2O, was synthesized using a one-pot reaction from 5-methyl-3-pyrazolamine and copper(II) acetate in water under ambient conditions. The adsorption of carbon dioxide from air was facilitated by the addition of diethanolamine to the reaction mixture. While diethanolamine is not a component of the final product, it plays a pivotal role in the reaction by creating an alkaline environment, thereby enabling the adsorption of atmospheric carbon dioxide. The central copper(II) atom is in an (N2O2) square-planar coordination environment formed by two N atoms and two O atoms of two equivalent (5-methyl-1H-pyrazol-3-yl)carbamate ligands. Additionally, there are co-crystallized water molecules within the crystal structure of this compound. These co-crystallized water molecules are linked to the CuII mononuclear complex by O—H...O hydrogen bonds. According to Hirshfeld surface analysis, the most frequently observed weak intermolecular interactions are H...O/O...H (33.6%), H...C/C...H (11.3%) and H...N/N...H (9.0%) contacts.

The goal of this study is to synthesize, determine the structure, and examine the antimicrobial properties of novel Cu(II) and Au(III) complexes of 2,4-dithiouracil and its derivatives. These complexes were obtained by mixing aqueous solutions of the corresponding metal salts with the ligand dissolved in DMSO and aqueous NaOH, using a metal-to-ligand ratio of 1:4:2. The structures of the new compounds were analyzed by melting point determination, microwave plasma atomic emission spectrometry (MP-AES) for Cu and Au, inductively coupled plasma optical emission spectrometry (ICP-OES) for S, attenuated total reflection (ATR), solution and solid-state NMR, and Raman spectroscopy. The data for 2,4-dithiouracil obtained from the 1H NMR, 13C NMR, distortionless enhancement by polarization transfer spectrum (DEPT-135), proton–proton homonuclear correlation spectrum (1H-1H COSY), long-range 1H-13C heteronuclear multiple bond correlation experiment (HMBC), and heteronuclear single quantum coherence spectra (HSQC) aided the interpretation of the NMR data for the gold and copper complexes. Furthermore, the antimicrobial effect of the free ligands and their complexes was assessed against Gram-positive and Gram-negative bacteria, as well as yeasts.

The catalytic properties of three copper complexes, [Cu(en)2](ClO4)2 (1), [Cu(amp)2](ClO4)2, (2) and [Cu(bpy)2](ClO4)2 (3) (where en = ethylenediamine, amp = 2-aminomethylpyridine and bpy = 2,2′-bipyridine), were explored upon the oxidation of benzyl alcohol (BnOH). Maximized conversions of the substrates to their respective products were obtained using a multivariate analysis approach, a powerful tool that allowed multiple variables to be optimized simultaneously, thus creating a more economical, fast and effective technique. Considering the studies in a fluid solution (homogeneous), all complexes strongly depended on the amount of the oxidizing agent (H2O2), followed by the catalyst load. In contrast, time seemed to be statistically less relevant for complexes 1 and 3 and not relevant for 2. All complexes showed high selectivity in their optimized conditions, and only benzaldehyde (BA) was obtained as a viable product. Quantitatively, the catalytic activity observed was 3 > 2 > 1, which is related to the π-acceptor character of the ligands employed in the study. Density functional theory (DFT) studies could corroborate this feature by correlating the geometric index for square pyramid Cu(II)-OOH species, which should be generated in the solution during the catalytic process. Complex 3 was successfully immobilized in silica-coated magnetic nanoparticles (Fe3O4@SiO2), and its oxidative activity was evaluated through heterogenous catalysis assays. Substrate conversion promoted by 3-Fe3O4@SiO2 generated only BA as a viable product, and the supported catalyst’s recyclability was proven. Reduced catalytic conversions in the presence of the radical scavenger (2,2,6,6-tetrametil-piperidi-1-nil)oxil (TEMPO) indicate that radical and non-radical mechanisms are involved.

Abstract Ensuring healthy lives and promoting well-being for all at all ages is the third goal of the sustainable development plan, so it was necessary to identify the most important problems that threaten health in our world. The World Health Organization declared that antibiotic resistance is one of the uppermost global public health threats facing humanity and searching for new antibiotics is slow. This problem can be approached by improving available drugs to combat various bacterial threats. To circumvent bacterial resistance, three copper(II) complexes based on the pefloxacin drug were prepared and characterized using analytical, spectroscopic, and thermal techniques. The resulting data suggested the formation of one octahedral binary and two distorted square pyramidal ternary complexes. Fluorescence spectra results revealed the formation of a turn-on fluorophore for amino acid detection. Computational calculations investigated quantum and reactivity parameters. Molecular electrostatic potential profiles and noncovalent bond interaction-reduced density gradient analysis indicated the active sites on the complex surface. The complexes were subjected to six microbial species, where the octahedral binary complex provoked its antimicrobial potency in comparison with ternary complexes. The enhanced antimicrobial activity against gram-negative bacterium E-coli compared to gentamicin was exhibited by the three complexes. Docking simulation was performed based on the crystal structure of E. coli and S. pneumoniae receptors using 5I2D and 6O15 codes. The binary complex exhibited a potent fitness score with 5I2D (TBE = − 107 kcal/mol) while ternary complexes displayed the highest docked score of fitness with 6O15.

Two new ligands were synthesized with the goal of copper stabilization, N,N′-(2-methylpyridine)-2,11-diaza[3,3](2,6)pyridinophane (PicN4) and N-(methyl),N′-(2-methylpyridine)-2,11-diaza[3,3](2,6)pyridinophane (PicMeN4), by selective functionalization of HN4 and TsHN4. These two ligands, when reacted with various copper salts, generated both Cu(II) and Cu(I) complexes. These ligands and Cu complexes were characterized by various methods, such as NMR, UV-Vis, MS, and EA. Each compound was also examined electrochemically, and each revealed reversible Cu(II)/Cu(I) redox couples. Additionally, stability constants were determined via spectrophotometric titrations, and radiolabeling and cytotoxicity experiments were performed to assess the chelators relevance to their potential use in vivo as 64Cu PET imaging agents. [ABSTRACT FROM AUTHOR]

A mononuclear square-planar CuII complex of (5-methyl-1H-pyrazol-3-yl) carbamate, [Cu(C5H6N3O2)2]⋅4H2O, was synthesized using a one-pot reaction from 5-methyl-3-pyrazolamine and copper(II) acetate in water under ambient conditions. The adsorption of carbon dioxide from air was facilitated by the addition of diethanolamine to the reaction mixture. While diethanolamine is not a component of the final product, it plays a pivotal role in the reaction by creating an alkaline environment, thereby enabling the adsorption of atmospheric carbon dioxide. The central copper(II) atom is in an (N2O2) squareplanar coordination environment formed by two N atoms and two O atoms of two equivalent (5-methyl-1H-pyrazol-3-yl)carbamate ligands. Additionally, there are co-crystallized water molecules within the crystal structure of this compound. These co-crystallized water molecules are linked to the CuII mononuclear complex by O--H⋯O hydrogen bonds. According to Hirshfeld surface analysis, the most frequently observed weak intermolecular interactions are H⋯O/O⋯H (33.6%), H⋯C/C⋯H (11.3%) and H⋯N/N⋯H (9.0%) contacts. [ABSTRACT FROM AUTHOR]

Five coordination compounds [Cu2(Bipy)2L4]·C2H5OH (Iа, Ib), [Cu2(Dmbipy)2L4] (II), [Cu2(Phen)2L4]·H2O (IIIa), [Cu2(Dmphen)2L4] (IVa), and [Cu2(Phendione')2L4]·2C2H5OH·2H2O (V) are synthesized from 5-(4-chlorophenyl)-1H-tetrazole (HL), where Bipy is 2,2'-bipyridine, Dmbipy is 4,4'-dimethyl-2,2'-bipyridine, Phen is 1,10-phenanthroline, Dmphen is 4,7-dimethyl-1,10-phenanthroline, and Phendione' is 6-ethoxy-6-hydroxy-1,10-phenanthrolin-5-one. The crystal structures of the complexes are determined by X-ray diffraction (XRD) of single crystals (CIF files CCDC nos. 2225368 (Ia), 2225369 (Ib), 2225370 (II), 2225372 (IIIa), 2225373 (IVa), and 2225371 (V)). The compounds are binuclear due to the bridging function of the tetrazolate anion, and the coordination number of copper is five in all synthesized complexes. The cytotoxic activity of the complexes against the Hep2 and HepG2 cancer cell lines and non-cancerous human fibroblasts MRC-5 is studied. The complexes exhibit pronounced cytotoxic properties, and compound V has the maximum selectivity index with respect to the cancer cells. [ABSTRACT FROM AUTHOR]

Three new ligands viz, benzylacetone-benzoylhydrazone [babh (L)], para-hydroxy-benzylacetone-2 3 benzoylhydrazone [p-OH-babh (L)] and para-nitrobenzylacetone-benzoylhydrazone [p-NO -babh (L)], were 2 synthesised by condensation of hydrazides with benzylacetone. The ligands were each reacted with copper(II) - - salts (chloride, nitrate, acetate and sulphate) to form complexes with the general formulae ML X (X = Cl, NO, 2 2 3 - - 1 AcO and SO). The compounds were characterised using H NMR, Infrared and UV-Visible spectroscopy, as 4 well as CHN elemental analyser and magnetic susceptibility measurements. Antibacterial activity of the ligands and synthesised complexes were investigated using the agar diffusion method against two Gram-positive (Staphylococcus aureus NCTC 6571 and Bacillus cereus ATCC 11778) and three Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 10145, Klebsiella pneumonia ATCC 13048) bacterial strains. However, the observed antimicrobial strength of the synthesized compounds was rather low. [ABSTRACT FROM AUTHOR]

Two coordination compounds of copper(II) with N′-(3-tert-butyl-5-nitro-2-hydroxybenzylidene) isonicotinohydrazide (H2L) are synthesized in MeOH in the presence of Et3N and with the addition of 1,10-phenanthroline (phen). It is shown the formation of these compounds is accompanied by the transformation of the starting N′-(3,5-di-tert-butyl-2-hydroxybenzylidene)isonicotinohydrazide acylhydrazone (H2L′) into N′-(3-tert-butyl-5-nitro-2-hydroxybenzylidene) isonicotinohydrazide (H2L) to form the [Cu(L)(MeOH)]n (1) 1D coordination polymer and the [Cu(L)(phen)] (2) molecular complex. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and catalytic activity of copper(II)‐bis(imino)pyridine pincer complexes were described. The copper(II) complexes (2 a and 2 b) were synthesized by the reaction of 2,6‐bis(imino)pyridine ligands with CuCl2 ⋅ 2H2O in methanol as a solvent. The copper(II) complexes were fully characterized by IR, UV‐Visible, Mass spectroscopy and elemental analysis. The copper(II) complexes 2 a and 2 b showed excellent catalytic activity towards azide‐alkyne cycloaddition (Click reaction) in water and produced regioselective product of 1,4‐disubstituted‐1,2,3‐triazoles. The copper(II) complex (2 b) with electron withdrawing CF3 group exhibited comparatively higher catalytic activity in azide‐alkyne cycloaddition reactions and produced up to 93 % of yield with 0.05 mol % of the catalyst loading. [ABSTRACT FROM AUTHOR]

Based on physicochemical, mass, UV-visible IR, and ESR spectrum analyses, copper complexes of HANH, MBINH, and MAINH are characterized. The typical formula for the copper complexes of HANH is M L2 (where L = HANH). The tridentate HANH ligand functions as a mono-negative ligand. The typical formula for copper complexes of MBINH & MAINH is [ML2]CL2 (M=Cu, L=MBINH & MAINH), and these ligands behave as neutral tridentate ligands. The octahedral geometry for the complexes is represented by UV-VIS spectral data. ESR spectra are used to examine the copper complexes at liquid nitrogen temperature (LNT). Redox potentials of all complexes are shifted towards + or - values in the CV data when compared with the ligands. In the current work, the antibacterial activity of ligands and metal complexes is also studied. [ABSTRACT FROM AUTHOR]

Ensuring healthy lives and promoting well-being for all at all ages is the third goal of the sustainable development plan, so it was necessary to identify the most important problems that threaten health in our world. The World Health Organization declared that antibiotic resistance is one of the uppermost global public health threats facing humanity and searching for new antibiotics is slow. This problem can be approached by improving available drugs to combat various bacterial threats. To circumvent bacterial resistance, three copper(II) complexes based on the pefloxacin drug were prepared and characterized using analytical, spectroscopic, and thermal techniques. The resulting data suggested the formation of one octahedral binary and two distorted square pyramidal ternary complexes. Fluorescence spectra results revealed the formation of a turn-on fluorophore for amino acid detection. Computational calculations investigated quantum and reactivity parameters. Molecular electrostatic potential profiles and noncovalent bond interaction-reduced density gradient analysis indicated the active sites on the complex surface. The complexes were subjected to six microbial species, where the octahedral binary complex provoked its antimicrobial potency in comparison with ternary complexes. The enhanced antimicrobial activity against gram-negative bacterium E-coli compared to gentamicin was exhibited by the three complexes. Docking simulation was performed based on the crystal structure of E. coli and S. pneumoniae receptors using 5I2D and 6O15 codes. The binary complex exhibited a potent fitness score with 5I2D (TBE = − 107 kcal/mol) while ternary complexes displayed the highest docked score of fitness with 6O15. [ABSTRACT FROM AUTHOR]

In order to study the physicochemical and biological properties of the coordination compounds of bioactive metal ions with 2-hydroxyphenylphosphonic acid derivatives, the reactions of 2-hydroxy-5-ethylphenylphosphonic acid (Н3L1) with copper(II) perchlorate, sulfate, nitrate, and acetate in water was studied for the first time. It has been found that, regardless of the ratio of reagents, in the case of copper(II) perchlorate, sulfate, and nitrate, a complex of the composition [Cu(H2L1)2(Н2О)2] is formed in high yields, whereas in the case copper(II) acetate a complex [Cu(HL1)(H2O)2] is formed, the composition of which was determined by elemental analysis and IR and electronic spectroscopy. The quantum-chemical calculations for the [Cu(H2L1)2(Н2О)2] and [Cu(HL1)(H2O)2] complexes by the density functional theory (DFT) method were carried out for the first time. The cytotoxic properties of the Н3L1 acid and the [Cu(HL1)(H2O)2] and [Cu(H2L1)2(Н2О)2] complexes with respect to HeLa tumor cells of human cervical adenocarcinoma were studied. The accumulation of the above complexes in HeLa cells was proved by laser confocal microscopy. [ABSTRACT FROM AUTHOR]

The geometrical structure of CuL2 (I), where L = R1N(O)–(O)CR2, R1 = Me, R2 = Ph, was studied by X-ray diffraction in the crystalline state and by stationary ESR spectroscopy in solution. In the crystalline state, I is a chain polynuclear complex. According to ESR data, in frozen solutions, complex I exists as three species, two being mononuclear and one being binuclear. The magnetic resonance parameters and concentrations of the species in frozen solutions were determined. The electronic structure of the complex with full geometry optimization of all systems was calculated in terms of the unrestricted density functional theory (DFT) method. [ABSTRACT FROM AUTHOR]

In this work, we present the results from a study of the speciation of the ternary systems formed by copper(II),2-(benzo(d)oxazol-2-yl)nicotinic acid (Oxa, HL) as the main ligand, and the amino acids Serine (Ser, A–), Threonine (Thr, A–), Methionine (Met, A–), Phenylalanine (Phe, A–), Aspartate (Asp, A2–), Glutamate (Glu, A2–), and Histidine (His, A–) as secondary ones. The potentiometric data was analyzed using the computational program LETAGROP for systems in aqueous solution at 25 °C and 1.0 M KNO3 as the ionic medium. The ternary complexes [Cu(L)(HA)]+, [Cu(L)(A)], [Cu(L)2(A)]–, [Cu(L)(A)2]–, [Cu(L)(A)(OH)]– and [Cu(L)(A)(OH)2]2– were detected. The relative stability of the ternary complexes was compared to the binary ones considering the values of ΔlogK and logχ (defined in text of results and analysis). Subsequently using the formation constants, the species distribution diagrams were generated and are briefly discussed. The UV–visible spectra of the ternary complexes show a maximum at 610–654 nm indicating that the Cu2+ is penta-coordinated. [ABSTRACT FROM AUTHOR]

The interest in the use of copper as a metal scaffold for the development of novel chemotherapeutics has considerably grown in recent years. This is mainly due to the relatively lower toxicity of copper complexes with respect to platinum drugs (i.e., cisplatin), the different mechanisms of action, and the cheaper cost. In the last decades, hundreds of copper-based complexes were developed and screened as anticancer agents, with the antesignanus of all compounds being copper bis-phenanthroline [Cu(phen)2]2+ developed by D.S. Sigman in the late 1990s. In particular, copper(phen) derivatives have been shown high interest in their capacity to interact with DNA by nucleobase intercalation. Here, we report the synthesis and chemical characterization of four novel copper(II) complexes functionalised with phenanthroline derivatives containing biotin. Biotin, also known as Vitamin B7, is involved in a series of metabolic processes, and its receptors are often overexpressed in many tumour cells. A detailed biological analysis including cytotoxicity in 2D and 3D, cellular drug uptake, DNA interaction, and morphological studies are discussed. [ABSTRACT FROM AUTHOR]

Structures of two new copper(II) chloride complexes with 2,5-bis(ethylthio)-1,3,4-thiadiazole (L), mononuclear CuL2Cl2 and tetranuclear Cu4L4Cl8, are determined by X-RAY diffractometry. The polycrystalline phase of the CuL2Cl2 complex is determined and studied by CHN analysis, IR spectroscopy, powder XRD, and static magnetic susceptibility methods. [ABSTRACT FROM AUTHOR]

The effects of two anticancer active copper(II) mixed-ligand complexes of the type [Cu(qui)(mphen)]Y·H2O, where Hqui = 2-phenyl-3-hydroxy- 1H-quinolin-4-one, mphen = bathophenanthroline, and Y = NO3 (complex 1) or BF4 (complex 2) on the activities of different isoenzymes of cytochrome P450 (CYP) have been evaluated. The screening revealed significant inhibitory effects of the complexes on CYP3A4/5 (IC50 values were 2.46 and 4.88 μM), CYP2C9 (IC50 values were 16.34 and 37.25 μM), and CYP2C19 (IC50 values were 61.21 and 77.07 μM). Further, the analysis of mechanisms of action uncovered a non-competitive type of inhibition for both the studied compounds. Consequent studies of pharmacokinetic properties proved good stability of both the complexes in phosphate buffer saline (>96% stability) and human plasma (>91% stability) after 2 h of incubation. Both compounds are moderately metabolised by human liver microsomes (<30% after 1 h of incubation), and over 90% of the complexes bind to plasma proteins. The obtained results showed the potential of complexes 1 and 2 to interact with major metabolic pathways of drugs and, as a consequence of this finding, their apparent incompatibility in combination therapy with most chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

Three new tripod tetradentate phenolate-amines (H2L1, H2L4 and H2L9), together with seven more already related published ligands, were synthesized, and characterized. With these ligands, two new dinuclear doubly-bridged-phenoxido copper(II) complexes (3, 4), and six more complexes (1, 2, 5–8), a new trinuclear complex (9) with an alternative doubly-bridged-phenoxido and –methoxido, as well as the 1D polymer (10) were synthesized, and their molecular structures were characterized by spectroscopic methods and X-ray single crystal crystallography. The Cu(II) centers in these complexes exhibit distorted square-pyramidal arrangement in 1–4, mixed square pyramidal and square planar in 5, 6, and 9, and distorted octahedral (5+1) arrangements in 7 and 8. The temperature dependence magnetic susceptibility study over the temperature range 2–300 K revealed moderate–relatively strong antiferromagnetic coupling (AF) (|J| = 289–145 cm−1) in complexes 1–6, weak-moderate AF (|J| = 59 cm−1) in the trinuclear complex 9, but weak AF interactions (|J| = 3.6 & 4.6 cm−1) were obtained in 7 and 8. No correlation was found between the exchange coupling J and the geometrical structural parameters of the four-membered Cu2O2 rings. [ABSTRACT FROM AUTHOR]

Herein, we discuss the synthesis, structural and spectroscopic characterization, and biological activity of five heteroligand copper(II) complexes with diethylnicotinamide and various fenamates, as follows: flufenamate (fluf), niflumate (nifl), tolfenamate (tolf), clonixinate (clon), mefenamate (mef) and N, N-diethylnicotinamide (dena). The complexes of composition: [Cu(fluf)2(dena)2(H2O)2] (1), [Cu(nifl)2(dena)2] (2), [Cu(tolf)2(dena)2(H2O)2] (3), [Cu(clon)2(dena)2] (4) and [Cu(mef)2(dena)2(H2O)2] (5), were synthesized, structurally (single-crystal X-ray diffraction) and spectroscopically characterized (IR, EA, UV-Vis and EPR). The studied complexes are monomeric, forming a distorted tetragonal bipyramidal stereochemistry around the central copper ion. The crystal structures of all five complexes were determined and refined with an aspheric model using the Hirshfeld atom refinement method. Hirshfeld surface analysis and fingerprint plots were used to investigate the intermolecular interactions in the crystalline state. The redox properties of the complexes were studied and evaluated via cyclic voltammetry. The complexes exhibited good superoxide scavenging activity as determined by an NBT assay along with a copper-based redox-cycling mechanism, resulting in the formation of ROS, which, in turn, predisposed the studied complexes for their anticancer activity. The ability of complexes 1–4 to interact with calf thymus DNA was investigated using absorption titrations, viscosity measurements and an ethidium-bromide-displacement-fluorescence-based method, suggesting mainly the intercalative binding of the complexes to DNA. The affinity of complexes 1–4 for bovine serum albumin was determined via fluorescence emission spectroscopy and was quantitatively characterized with the corresponding binding constants. The cytotoxic properties of complexes 1–4 were studied using the cancer cell lines A549, MCF-7 and U-118MG, as well as healthy MRC-5 cells. Complex 4 exhibited moderate anticancer activity on the MCF-7 cancer cells with IC50 = 57 μM. [ABSTRACT FROM AUTHOR]

The possibility of the complex formation of three bispidines with copper(ii) chloride and acetate in a deuterated DMF solution was studied by NMR titration. For all ligands, the formation of complexes with copper(ii) chloride was clearly detected based on the changes in the signals in the proton NMR spectra. The formation of complexes with copper(ii) acetate was not observed for any of the ligands. The results of the study can be used in the design of metal complex catalysts for the Henry reaction. [ABSTRACT FROM AUTHOR]

Mononuclear copper(II) complexes based on the symmetric tridentate N3-donor ligands bis(pyridin-2-yl)methyl)amine (HBPA, L1) and its methylated counterpart, di(2-pyridylmethyl)amine (MeDPA, L2) have been prepared, characterized, and demonstrated as the functional models for lytic polysaccharide monooxygenase. These complexes disrupt the synthetic substrate, such as p-nitrophenyl-b-D-glucopyranoside (b-PNPG) into p-nitrophenol (PNP) and D-allose via oxidative cleavage as LPMOs do in nature. The observed spectroscopic and kinetic analysis have revealed that the reaction proceeds via copper(II) hydroperoxide as intermediate, whose electronic spectral signature has appeared at 350nm in the electronic absorption spectra with the formation rate of 1.61 and 9.06×10-3 s1 respectively for complexes 1 and 2. Especially the obtained product was newly appeared at 400nm, indicates the formation of p-nitrophenol with the rate of 7.52 and 5.45×10-3 s1 for complexes 1 and 2 respectively. These results affirm the ability of copper complexes as the functional models of LPMOs. [ABSTRACT FROM AUTHOR]

The aim of the present study is to synthesize new metal complexes of 6-methyl-2-thiouracil and 6-propyl-2-thiouracil, elucidate their structures, and investigate their biological properties. All metal complexes were obtained after mixing water solutions of the corresponding metal salts and the ligand dissolved in DMSO and water solutions of NaOH in a metal-to-ligand ratio of 1:4:2. The structures of the new compounds are discussed based on melting point analysis (MP-AES) for Cu and Pd, UV-Vis, IR, ATR, 1H NMR, 13C NMR, and Raman spectroscopy. The interpretation of complex spectra is assisted by the data for 6-methyl-2-thiouracil and 6-propyl-2-thiouracil obtained from 1H-1H COSY, DEPT-135, HMBC and HMQC spectra. In addition, the antimicrobial activity of these complexes and the free ligands are assessed against both Gram-positive and Gram-negative bacteria, as well as yeasts. In general, the addition of metal ions improved the antimicrobial activity of both 6-methyl-2-thiouracil and 6-propyl-2-thiouracil. The Cu(II) complex with 6-methyl-2-thiouracil and the Pd(II) complex with 6-propyl-2-thiouracil exhibited the highest activity against the test microorganisms.

Two new copper(ii) complexes [CuL1] (1) and [CuL2] (2) derived from azo-based ligands 2-hydroxy-5-p-tolylazo-benzaldehyde (HL1) and 1-(2-hydroxy-5-p-tolylazo-phenyl)-ethan-one (HL2) were synthesized. These two ligands and their metal complexes were characterized by elemental analysis, nuclear magnetic resonance (1H and 13C), infrared, and UV/Vis spectroscopic techniques. Spectroscopy and other theoretical studies reveal the geometry of copper complexes, and their binding affinity towards nucleic acids are major groove binding.

A series of six heteroleptic copper(II) complexes with 2′-hydroxy-4-(dimethylamino)chalcone (HL) with the composition [Cu(N-N)(L)]NO3 (1–6), where N-N stands for dmbpy = 5,5′-dimethyl-2,2′-bipyridine (1), bphen = 4,7-diphenyl-1,10-phenanthroline (2), dbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine (3), nphen = 5-nitro-1,10-phenanthroline (4), bpy = 2,2′-bipyridine, (5), and dpa = 2,2′-dipyridylamine (6), was prepared and thoroughly characterized. The in vitro cytotoxicity screening on eight human cancer cell lines identified complex 2, containing the bulkiest N-donor ligands (bphen) as highly cytotoxic against cancer cells, with IC50 values ranking from 1.0 to 2.3 μM, with good selectivity and low toxicity against healthy human fetal lung fibroblasts MRC-5. The cell-based assays, involving the most effective complex 2 in A2780 cancer cells, revealed its strong pro-apoptotic effects based on the effective activation of caspases 3/7, ROS overproduction, and autophagy in the A2780 cells while not impeding the cell cycle and mitochondrial membrane functions. The cellular uptake studies in A2780 and 22Rv1 cells uncovered no intracellular transport of the cationic complex 2, supporting the hypothesis that the in vitro anticancer effects of complex 2 are based on the combined extrinsic activation of apoptosis and autophagy induction. [ABSTRACT FROM AUTHOR]