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On treatment of copper(II) acetate with aryl hydrazone ligands, four new solid derivatives of copper(II) were produced in appreciable yields. Various characterization techniques including infrared, UV-visible, NMR, electron paramagnetic resonance and mass spectroscopies, elemental analysis, scanning electron microscopy, powder X-ray diffraction and thermogravimetric analysis revealed a tetra-coordination in all the mononuclear crystalline complexes with high thermal stability. Further, significant interaction of these novel complexes with calf thymus DNA via intercalative mode of binding was revealed by electronic absorption spectroscopy. The chemical nuclease activity of the complexes on pBR322 DNA was investigated in the presence and absence of oxidizing agent (H2O2). A potent nuclease activity was observed only in the presence of H2O2. Further, antibacterial and antifungal studies of the new ligands and complexes revealed that the latter possessed comparatively better activity. [ABSTRACT FROM AUTHOR]

Sulfamethoxazolyl-azo-phenols [SMX-N=N-CH(R)(R)-OH] ( 1a, 2a) and their Cu(II) complexes, [Cu(SMX-N=N-CH(R)(R)-O)] ( 1b, 2b) (R = p-OMe, R = H, 1a/1b; R = p-Cl, R = m-CH, 2a/2b) show antibacterial sensitivity against Gram-positive bacteria, B. subtillis; IC: 281.47 ± 1.84 μM ( 1a), 126.39 ± 1.66 μM ( 1b), and 279.94 ± 3.15 μM ( 2a), 123.62 ± 1.27 μM( 2b), and Gram-negative bacteria, E. coli; IC: 204.66 ± 3.31 μM ( 1a) and 89.05 ± 1.48 μM ( 1b), 223.13 ± 2.71 μM ( 2a), and 98.26 ± 1.59 μM ( 2b). Interaction of DNA with free ligand ( 1a and 2a) is insignificant, while the complexes ( 1b and 2b) interact strongly and the binding constants are K , 8.413 × 10 M ( 1b) and 6.56 × 10 M ( 2b). Optimized structures of the compounds are docked with protein structure of DHPS ( E. coli) to propose the most favoured binding mode of the drugs in the active site. The in silico test of the compound helps to understand drug metabolism, drug-protein interactions, and toxicity (ADMET). Graphical abstract: [ABSTRACT FROM AUTHOR]

Four homoleptic copper(II) complexes, [Cu(Meophtpy)](ClO) (Meophtpy = 4′-(4-methoxylphenyl)- 2,2′:6′,2″-terpyridine) ( I), [Cu(Meophtpy)](ClO) · 2HO ( II), [Cu( m-Clphtpy)](ClO) ( m-ClPhtpy = 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine) ( III), and [Cu( m-ClPhtpy)](ClO) ( IV) have been synthesized by hydrothermal methods and characterized by IR, elemental analysis and single crystal X-ray diffraction (CIF files CCDC nos. 963375 ( I), 885457 ( II), 963377 ( III), and 963376 ( IV)). Complex II is a polymorph of I and complex IV is a polymorph of III. All these complexes are obtained with 95% ethanol solution or 50% ethanol solution and the solvent control on the crystallization are obviously found. In all complexes, the face-to-face interactions between pyridyl rings or phenyl rings facilitate the construction of 3D network in the crystal in addition to hydrogen bonds. The fluorescence properties of these complexes have been investigated. [ABSTRACT FROM AUTHOR]

Functionalized acid amides are widely used in biology, medicine, environmental chemistry and many other areas. Among them, pyridine-substituted amides, in particular N-(pyridin-2-yl)acetamide and its derivatives, play an important role due to their excellent chelating properties. The donor properties of these ligands can be effectively modified by introducing electron-donating substituents ( e.g. alkyl groups) into the heterocycle. On the other hand, substituents in the α-position of the pyridine ring can create steric hindrance, which significantly influences the coordination number and geometry. To achieve a better understanding of these effects, copper(II) complexes with sterically demanding N-(6-methylpyridin-2-yl)acetamide ligands ( L) and monoanions of different size, shape and coordination ability have been chosen as model compounds. The crystal structures of three new compounds, bromidobis[ N-(6-methylpyridin-2-yl-κ N)acetamide-κ O]copper(II) bromide, [CuBr(C8H10N2O)]Br, (I), aquabis[ N-(6-methylpyridin-2-yl-κ N)acetamide-κ O]copper(II) dinitrate, [Cu(C8H10N2O)(H2O)](NO3)2, (II), and aquabis[ N-(6-methylpyridin-2-yl-κ N)acetamide-κ O]copper(II) bis(perchlorate), [Cu(C8H10N2O)(H2O)](ClO4)2, (III), have been determined by single-crystal X-ray diffraction analysis. It has been shown that the presence of the 6-methyl group results in either a distorted square-pyramidal or a distorted trigonal-bipyramidal coordination geometry around the CuII centres instead of the typical octahedral geometry observed when the methyl substituent is absent or occupies any other position on the pyridine ring. Moreover, due to the steric hindrance provided by the L ligands, only the bromide ligand, the smallest of the series, enters into the first coordination sphere of the CuII ion in (I). In (II) and (III), the vacant coordination site of the CuII ion is occupied by a water molecule, while the nitrate and perchlorate anions are not involved in coordination to the metal centre. The structures of (I)-(III) are characterized by the presence of one-dimensional infinite chains formed by hydrogen bonds of the types N-H...Br [in (I)], N-H...O and O-H...O [in (II) and (III)] between the amide groups of the L ligands, the coordinated water molecules and the uncoordinated anions. The hydrogen-bonded chains are further interconnected through π-π stacking interactions between the pyridine rings of the L ligands, with approximate interplanar separations of 3.5-3.6 Å. [ABSTRACT FROM AUTHOR]

Four novel ON donor Schiff bases (E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol (HL1),(E)-3-((4-(4-biphenyloxy)phenyliminomethyl)benzene-1,2-diol (HL2), (E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol (HL3), (E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol (HL4) and their copper(II) complexes bis((E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L1)2) bis((E)-3-((4-(4-biphenyloxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L2)2), bis((E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L3)2), bis((E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L4)2) have been synthesized and characterized by spectroscopic (FTIR, NMR, UV–visible) and elemental analysis. The crystal structures of HL1, HL2, HL3,and HL4have been determined, which reveal intramolecular N-H⋯O (HL1, HL2, HL3,and HL4) hydrogen bonds in the solid state. Keto-amine and enol-imine tautomerism is exhibited by the Schiff bases in solid and solution states. The Schiff bases and their copper(II) complexes have been screened for their biological activities. In antimicrobial assays (antibacterial and antifungal), HL4showed promising results against all strains through dual inhibition property while the rest of the compounds showed activity against selective strains. On the other hand, in cytotoxic, DPPH, and inhibition of hydroxyl (OH) free radical-induced DNA damage assays, the results were found significantly correlated with each other,i.e.the ligands HL1and HL2showed moderate activity while their complexes Cu(L1)2and Cu(L2)2exhibited prominent increase in activity. As the results of these assays are supporting each other, it represents the strong positive correlation and antioxidant nature of investigated compounds. [ABSTRACT FROM AUTHOR]

The fixation and activation of molecular oxygen on copper(II) complexes with 5-hydroxy and 5-aminoorotic acids, leading to oxidation of the ligand. [ABSTRACT FROM AUTHOR]

Five new copper(II) complexes of the type [Cu(N O)(N N)(ClO 4 ) 2 ], in which N O = 4-fluorophenoxyacetic acid hydrazide (4-FH) or 4-nitrobenzoic hydrazide (4-NH) and N N = 1,10-phenanthroline (phen), 4–4′-dimethoxy-2-2′-bipyridine (dmb) or 2,2-bipyridine (bipy) were synthesized and characterized using various spectroscopic methods. The X-ray structural analysis of one representative compound indicates that the geometry around the copper ion is distorted octahedron, in which the ion is coordinated to hydrazide via the terminal nitrogen and the carbonyl oxygen, and to heterocyclic bases via their two nitrogen atoms. Two perchlorate anions occupy the apical positions, completing the coordination sphere. The cytotoxic activity of compounds was investigated in three tumor cell lines (K562, MDA-MB-231 and MCF-7). Concerning K562 cell line, the complexes with 1,10-phenanthroline exhibit high cytotoxic activity and are more active than carboplatin, free ligands and [Cu(phen) 2 ] 2 + . Considering the cytotoxicity results, further investigations for the compounds [Cu(4-FH)(phen)(ClO 4 ) 2 ] I and [Cu(4-NH)(phen)(ClO 4 ) 2 ]∙H 2 O III were performed. Flow cytometric analysis revealed that these complexes induce apoptotic cell death in MDA-MB-231 cell line and bind to DNA with K values of 4.38 × 10 4 and 2.62 × 10 4 , respectively. These compounds were also evaluated against wild type Mycobacterium tuberculosis (ATCC 27294) and exhibited antimycobacterial activity, displayed MIC values lower than those of the corresponding free ligands. [ABSTRACT FROM AUTHOR]

The small differences in synthesis condition led to formation of four new copper(II) salicylatocomplexes – two differently polymeric [Cu(4-MeOSal) 2 (μ-H 2 O) 2 ] n 1, [Cu(μ-3,5-Br 2 Sal) 2 (H 2 O) 2 ] n 2 and two dimeric [Cu(5-MeSal) 2 (MeOH)] 2 ⋅2MeOH 3 [Cu(4-MeSal) 2 (EtOH) 2 ] 2 4 compounds, where 4-MeOSal = 4-methoxysalicylate, 3,5-Br 2 Sal = 3, 5-dibromsalicylate, 5-MeSal = 5-methylsalicylate, and 4-MeSal = 4-methoxysalicylate monoanion. Complexes were characterized by elemental analysis, UV–Vis, infrared, EPR spectra and single crystal X-ray analysis. Spectral properties are in good agreement with structural information. Intermolecular interactions are responsible for building supramolecular structure. The complexes 1 and 2 build up 2D supramolecular structures by the O–H⋯O hydrogen bonds formation while the complexes 3 and 4 are forming 1D supramolecular chain of paddle wheel units and coordinated solvent molecules. [ABSTRACT FROM AUTHOR]

Copper (Cu)(II) complexes were synthesized by Ind-3-COOH combined with N-containing auxiliary ligands via a combinatorial strategy involving hydrothermal and solvent-evaporation method. The synthesized complexes had the following formulas: [Cu(Ind-3-COO)] ( 1), [Cu(PHEN)(Ind-3-COO)]·2HO ( 2), [Cu(DPP)(Ind-3-COO)(HO)]·HO, ( 3) and [Cu(BPY)(Ind-3-COO)]·4HO ( 4). Meanwhile, the symbol abbreviations were listed as follows: Ind-3-COOH = 1 H-indazole-3-carboxylic acid, 1,3-bis(4-pyridyl)propane (DPP), 1,10-phenanthroline (PHEN) and 4,4′-bipyridine (BPY). The crystalline structure and spectroscopy of each complex were characterized by single-crystal X-ray diffraction, elemental analysis, Fourier transform infrared spectroscopy and powder X-ray diffraction. The redox reactions in the complexes were then investigated by performing cyclic voltammetry under nitrogen conditions at room temperature. Two pairs of distinctive irreversible reduction potentials were identified, which could be attributed to the processes of Cu(II)-Cu(I) and Cu(I)-Cu(0). [ABSTRACT FROM AUTHOR]

The reactions of N -arylalkyl derivatives of iminodiacetamide (Bnimda, Peimda, Ppimda; Bn = benzyl, Pe = 2-phenylethyl; Pp = 3-phenylprop-1-yl) with copper(II) sulfate and sodium perchlorate in aqueous solutions were investigated. Three new copper(II) complexes [Cu(Bnimda) 2 ](ClO 4 ) 2 ( 1 ), [Cu(Peimda) 2 ](ClO 4 ) 2 ( 2 ) and [Cu(Ppimda) 2 ](ClO 4 ) 2 ·2H 2 O ( 3 ) were prepared and characterized by infrared spectroscopy and thermal analysis (TG/DTA). Complex 2 was found to be explosive upon heating. The octahedral coordination environments around the copper(II) ions in complexes 1 and 3 consist of two O , N , O ′-tridentate N -arylalkyliminodiacetamide ligands, with imino N atoms in trans -position. Molecules are interconnected by extensive hydrogen bonding between the amide moieties and perchlorate ions or water molecules, forming 3D networks in both structures. However, the difference in the hydrophobic chain lengths leads to significant differences in the hydrogen bonding motifs in the two structures. The molecular geometry and infrared spectra of these complexes were also studied by DFT calculations using B3LYP/6-311G(d,p) computational model. The calculated spectra and molecular geometry agree very well with the experimental results despite the extensive hydrogen bonding frameworks which are present in the crystal structures of these compounds. [ABSTRACT FROM AUTHOR]

To develop selective ligands for the separation of copper(II), nickel(II) and cobalt(II), the solvent extraction and coordination chemistry of a bidentate chelating ligand, N , N -dioctyl-2-aminomethylpyridine (AMPO), and a tridentate chelating ligand, tert-butyl 2-( N -octyl-2-picolyamino)acetate (AMPA), were investigated. The ligands exhibit excellent extraction ability and high selectivity towards copper(II) over nickel(II) and cobalt(II) in the simulated electrolysis anolytes. Two novel copper(II) complexes, [Cu 2 (AMPO) 2 Cl 4 ] ( 1 ) and [Cu(AMPA)Cl 2 ] ( 2 ), were synthesized and fully characterized. The solid-state structures of the complexes 1 and 2 were established by single crystal X-ray diffraction. The results show that the complex 1 consists of isolated dinuclear molecules unit with two bridging chloro ligands and the geometry around Cu(II) displays a slightly distorted square pyramid, and the complex 2 is also best described as a slightly distorted square pyramid in reasonable approximation distance. The stoichiometric ratios and association constants of the copper(II) complexes with AMPO and AMPA were also determined in CH 3 OH/H 2 O mixtures by UV−Vis spectrometry, respectively. The interactions between the ligands and the metal ions (Cu 2+ , Ni 2+ and Co 2+ ) were correspondingly evaluated by X-ray photoelectron spectroscopy (XPS) and electrospray ionization-mass spectrometry (ESI-MS), and the results reveal that AMPO can be correspondingly coordinated through tertiary amine N atom and pyridine N atom with the three metal ions of copper(II), nickel(II) and cobalt(II), and AMPA can be coordinated through tertiary amine N atom, pyridine N atom and the carbonyl O atom only with copper(II) not with nickel(II) or cobalt(II). All the results indicate that AMPA could be a better candidate for the deep removal of copper(II) from the nickel or cobalt electrolysis anolyte. [ABSTRACT FROM AUTHOR]

The coordination chemistry and antimicrobial profiles of three copper(II) complexes with 2-(imidazole-2-yl)heteroaryl ligands, named impy, impz and impm, have been investigated. Based on X-ray structure determination the complexes present square planar geometry with coordination formulas [CuCl 2 (imp x )], where x = y, z or m. Elemental analysis and mass spectrometric results are in agreement with the proposed compositions. Vibrational spectroscopy and molecular modeling provided further evidences that the [CuCl 2 (impz)] complex, which did not have its structure solved by X-ray diffraction, adopts a similar geometry of the other two complexes. Electronic spectroscopic data indicated that all three ligands led to a hypsochromic shift of the d-d band when compared to CuCl 2 ·2H 2 O and that the electronic structure of the ligands are significantly altered upon coordination to Cu(II). Electronic paramagnetic resonance studies in solution showed that the compounds present similar coordination environments. The MIC values of the complexes over E. coli and S. aureus was 17.8 μmol·mL −1 , thus no distinction was found between the complexes and the tested strain. The complexes were inactive over three tested fungal strains under the considered experimental conditions. [ABSTRACT FROM AUTHOR]

The title compound, [Cu(Imz-H)(Imz)(N)] ( 1) (Imz-H = imidazole) was prepared by the reaction of CuCl·2HO with imidazole and sodium azide, and its structure was determined by X-ray crystallography. The crystal structure shows that the complex exists in the form of a two dimensional polymer consisting of dimeric [Cu(Imz-H)(Imz)(N)] and monomeric [Cu(Imz-H)(Imz)(N)] units. In the dimeric part each Cu(II) ion is bound to two nitrogen atoms of Imz-H or Imz and three nitrogen atoms of azide adopting a distorted square pyramidal geometry. In the monomeric part, the copper atom is disordered over two positions and is coordinated to two imidazole molecules (Imz-H), two bridging imidazolate (Imz-) groups, and two weakly bound azide ions. In order to validate the obtained structure, the structures of two complexes; [Cu(Imz-H)(Imz)(HN)(N)] containing one monomer and one dimeric unit as a model of 1 and a hypothetical complex, [Cu(Imz-H)(Imz)(HN)(N)] containing only dimeric units were fully optimized at the B3LYP-D3 level of theory. The interaction energy between the dimeric and monomeric units in the former complex was found to be almost twice larger that calculated between the dimeric units in the later complex. Therefore, the theoretical results support that the experimentally determined structure ( 1) is energetically more preferred than that containing only the dimeric units. The natural bond orbital (NBO) analysis of the model complexes of ( 1) was performed and the distribution of spin density at the atoms of [Cu(Imz-H)(Imz)(HN)(N)] and [Cu(Imz-H)(Imz)(HN)(N)] was discussed. The NBO charge on copper cation in the dimeric unit is 0.90 e and is smaller than that on the Cu(II) ion in the monomeric unit by 0.09 e. Antimicrobial properties of the complex were evaluated by minimum inhibitory concentration and the results showed that the complex exhibited no significant activities against the selected microorganisms. [ABSTRACT FROM AUTHOR]

New copper complexes of 2-hydroxy-5-methoxyacetophenone thiosemicarbazone and its N(4)- substituted derivatives were synthesized and characterized by theoretical DFT studies and experimental UV–Vis, FT-IR, EPR spectral analysis, cyclic voltammetry, magnetic susceptibility and conductivity measurements. The DFT calculation results have been used to predict and interpret the experimental results. The geometric parameter G within the range of 7.61–7.86 for all complexes confirms the mononuclear nature of the complexes. The EPR, UV-Vis, DFT studies and obtained bonding parameters show that all the complexes have square planar geometry and their M-L bonds have strong ionic and some in-plane σ -bond character. In addition, the experimental and DFT studies showed that HOMO and LUMO energy levels of the complexes may present good electron transporting properties. Also, the investigated Cu(II) complexes were tested for biological activity, proving both in vitro antibacterial and anticancer activity. The complexes exhibited antibacterial activity against Gram positive bacteria S. aureus while exhibiting no activities against gram negative bacteria E. coli and S. gallinarum . The f parameters obtained experimentally by EPR support the antimicrobial activity properties results of the complexes. The evaluations of potential anticancer activity of these complexes were carried out against highly metastatic MDA-MB-231 breast adenocarcinoma cell line by MTT assay. Our results suggest that all tested copper complexes have high cytotoxic effects with the range of 1.76–3.53 μM IC 50 values in vitro . These copper complexes could be considered as potential anticancer agents to counteract drug resistance of metastatic cancer cells. [ABSTRACT FROM AUTHOR]

Four mononuclear copper(II) complexes, [Cu(LFQM-115)2] (1), [Cu(LFQM-116)2] (2), [Cu(LFQM-117)2] (3) and [Cu(octyloxy)2] (4) [LFQM-115 = 2-hydroxy-4-O-methylbenzophenone (C14H11O3), LFQM-116 = 2-hydroxy-4-O-butylbenzophenone (C17H18O3), LFQM-117 = 2-hydroxy-4-O-(33-dimethylallyl)benzophenone (C18H18O3) and octyloxy = 2-hydroxy-4-O-octylbenzophenone (C21H25O3)], have been prepared and investigated by infrared spectroscopy, thermal analysis, and powder and single crystal X-ray diffraction. Even though the synthesis and infrared analysis of1,2, and4have been reported previously, their crystal structures were elucidated for the first time here. In addition, the crystal structures of LFQM-116 and LFQM-117 were also determined by single crystal X-ray diffraction. The pseudo-translational symmetry found in LFQM-116 and the isomorphism between LFQM-115 and LFQM-117 are discussed. The complexes were prepared from a reaction of copper(II) nitrate trihydrate and the respective ligand in a (1:2) molar ratio in methanol (for1and2) or THF (for3and4) with addition of NaOH. Furthermore, crystallographic studies show that each copper(II) exhibits a square planar geometry, coordinated by four oxygens of two ligands. The nature and crystal packing of the intermolecular interactions are discussed. Compounds2and3are isomorphic crystals and all structures have the same supramolecular synthon. [ABSTRACT FROM PUBLISHER]

Binary and ternary complexes of copper(II) with the 2-(benzo[d]oxazol-2-yl)nicotinic acid (Ligand HL) and the amino acids Glycine (HGly, HB), Proline (HPro, HB), α-Alanine (Hα-Ala, HB), β-Alanine (Hβ-Ala, HB) were studied in aqueous solution at 25 °C, using 1.0 mol · dm − 3 KNO 3 as the ionic medium. The types of complexes formed and their overall stability constants were established on the basis of the computer analysis of the potentiometric data, using a version of the program LETAGROP. It was inferred that the aromatic oxazol Ligand L − 1 acts as a primary ligand in the ternary complexes, while the oxygen and nitrogen donor-containing amino acids are the secondary ligands. The analysis showed the formation of five complexes: [Cu(L)(HB)] + , Cu(L)(B), [Cu(L)(B)(OH)] − , [Cu(L) 2 (B)] − and [Cu(L)(B) 2 ] − in the Cu(II)-L − -Gly and Cu(II)-L − -βAla systems, for the Cu(II)-L − -Pro system, the complexes [Cu(L)(HB)] + , Cu(L)(B), [Cu(L)(B)(OH)] − and [Cu(L)(B) 2 ] − were detected and, finally, in the Cu(II)- L − - αAla system, only the complexes [Cu(L)(HB)] + , Cu(L)(B) and [Cu(L)(B)(OH)] − were observed. The concentration distributions of various species formed in aqueous solution were also evaluated as a function of pH. [ABSTRACT FROM AUTHOR]

Complexes based on different halogen-substituted nitronyl nitroxide radicals and Cu(II), Cu3(hfac)6(NIT-Ph-F)2(1) and Cu3(hfac)6(NIT-Ph-Cl)2(2) (hfac = hexafluoroacetylacetonate; NIT-Ph-F = 2-(4′-fluorophenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; NIT-Ph-Cl = 2-(4′-chlorphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), were synthesized and characterized structurally and magnetically. X-ray crystal structure analyses show that1and2have similar centrosymmetric five-spin structures consisting of three Cu(II) ions bridged by two nitroxide ligands. The Cu(II) is coordinated by six oxygens to form an octahedron, while the five coordination of the terminal Cu(II) ion is square pyramidal. Magnetic measurements reveal strong antiferromagnetic interactions between Cu(II) ions and radicals in1(J = −38.9 cm−1) and weak antiferromagnetic interactions between Cu(II) ions and radicals in2(J = −1.23 cm−1), which may be explained by the bond length of the Cu–Orad(2.468(2) Å) in1, which is shorter than that (2.514(2) Å) in2, and the dihedral angle (73.17(1)°) of the plane O7–O8–Cu(2)–O7A–O8A with the moiety O5–N1–C11–N2–O6 in1is smaller than (77.82(1)°) in2. [ABSTRACT FROM AUTHOR]

A series of four new copper(II) heteroleptic complexes, [Cu(2‴-pytpy) (L)] (NO 3 ) 2 ·2H 2 O ( 1–4 ), where 2‴-pytpy = 4′-(2′′′-Pyridyl)-2, 2′:6′, 2′′-terpyridine, L = bipyridyl (bpy), 1, 10 phenanthroline(phen), dipyridoquinoxaline(dpq) and dipyridophenazine (dppz) were synthesized and characterized by spectroscopic techniques. Further, the molecular structure of the complex (2) was confirmed by single crystal X-ray diffraction technique and the data revealed a penta coordinated, distorted square-pyramidal geometry with triclinic system. The interactions of four complexes with calf thymus DNA and bovine serum albumin (BSA) were investigated by electronic absorption, fluorescence and circular dichroism spectroscopy techniques. Spectral studies substantiated an intercalative binding mode of metal complexes with ct-DNA. Significant binding interactions of the complexes with protein have been further revealed from fluorescence studies. Furthermore, all the four complexes show potential cytotoxicity towards the human liver carcinoma cell line (HepG-2). [ABSTRACT FROM AUTHOR]

Hydrazides and their solid complexes demonstrate biological and pharmacological activity. The present study determines the hitherto undescribed coordinating properties of three hydrazides (acethydrazide, formic hydrazide and oxalodihydrazide) towards copper(II) in aqueous solutions by means of various potentiometric (ISE, pH-metric) and spectroscopic (UV–Vis, EPR) methods. The speciation models are than confirmed by ESI-MS. Due to metal-promoted deprotonation, the complexes are formed below pH 2 and coordination occurs with one, two or three ligand molecules. EPR spectroscopy revealed bidentate {N,O} coordination, leading to a five-membered chelate ring. Dissociation of the amide protons occurs only for acethydrazide by enolization which allows the formation of a complex with a twice-deprotonated ligand molecule. For the copper(II) systems with oxalodihydrazide and formic hydrazide, the amide groups of the ligands remain protonated, as the appearance of a precipitate at low pH limits further measurements. [ABSTRACT FROM AUTHOR]

Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H2O, [Cu(phen)(L-leu)Cl]·4½H2O, and [Cu(phen)(L-tyr)Cl]·3H2O, and four binary copper(II) complexes, [Cu(phen)Cl2],Cu(L-phe)2·½H2O, Cu(L-leu)2·½H2O, and Cu(L-tyr)2·H2O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl2, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin. [ABSTRACT FROM AUTHOR]

Three new water-soluble copper(II) complexes [Cu(HL)(H 2 O){(CH 3 ) 2 NCHO}] ( 1 ), [Cu(H 2 L) 2 (im) 4 ]·CH 3 OH ( 2 ) and [Cu(HL)(CH 3 OH)] 2 ( μ 2 -py) ( 3 ) were synthesized from copper(II) nitrate and sodium ( Z )-2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazinyl)benzene-sulfonate (NaH 2 L), in the absence (for 1 ) and presence of imidazole (im) (for 2 ) or pyrazine (py) (for 3 ), and fully characterized. The complexes 1–3 have been tested as stereoselective C H activating catalysts for the model nitroaldol (Henry) condensation of nitroethane with various aldehydes in water. 1 was the most active catalyst affording 64−87% yields with syn/anti diasteroselectivities up to 77:23. [ABSTRACT FROM AUTHOR]

A series of catenanes was synthesized via self-assembly of dibenzo-24-crown-8, ethylenediamine, and either three, four, or five cyclidene units coordinating nickel(II) or copper(II) ions. A number of molecular necklaces were successfully isolated and characterized. ESI mass spectrometry proved to be the most useful analytical tool to establish the exact composition of synthesized catenanes. Additionally, single crystal of a grand macrocycle composed of four tetraazamacrocyclic units complexing copper(II) ions was obtained and its X-ray structure has been successfully determined. [ABSTRACT FROM AUTHOR]

• A series of mixed-ligand Cu(II) complexes were synthesized and characterized. • The anti-lung cancer activity of these Cu complexes were evaluated in vitro. • We revealed the anticancer mechanism of the Cu(II) complex. • The ability of complex 4 to inhibit the growth of A549 tumor spheroids was assessed. [Display omitted] Here we synthesized five mixed-ligand copper(II) Schiff-base complexes, including [Cu(HL1)(pyridine) NO 3 ] 1 , [Cu(HL2)(pyridine)Cl] 2 , [Cu(HL3)(pyridine)Br] 3 , [Cu(HL4)(pyridine)Br] 4 , and [Cu(L5)(pyridine)] 5 , and performed a series of assays to investigate their anti-lung cancer activities in vitro. The structures of these copper(II) complexes were confirmed by X-ray crystallography and elemental analysis. MTT assay showed that complex 4 exhibited stronger cytotoxicity than other complexes. The wound healing assay showed that complex 4 had the well potential to display anti-metastatic activity. Flow cytometry and fluorescence imaging analysis showed that complex 4 led to cell cycle arrest at the S phase and induced mitochondria-mediated apoptotic. Furthermore, in the 3D A549 spherical model, complex 4 clearly exerts an inhibitory effect. [ABSTRACT FROM AUTHOR]

[Display omitted] Reaction of copper(II) acetate with cyclohexanoneselenosemicarbazone (Hcysesc), 5-chloro isatinselenosemicarbazone (5-ClHIstsesc), 1-methyl isatinselenosemicarbazone (1-MeHIstsesc), 3-indole selenosemicarbazone (3-HInsesc), 3-acetylindole selenosemicarbazone (3-AcHInsesc and 2-naphthaldehyde selenosemicarbazone (2-Hnaphsesc) in 1:2 (M: L) molar ratio yielded complexes of stiochiometry, [Cu(L) 2 ] 1 – 6 (L = cysesc 1 ; 5-ClIstsesc 2 ; 1-MeIstsesc 3 ; 3-Insesc 4 ; 3-AcInsesc 5 ; 2-naphsesc 6). All the complexes are characterized by IR, Mass and ESR spectroscopy. Two well defined g values (g ‖ and g ⊥) in ESR spectrum of complexes 1 – 4 , 6 indicate axial symmetry, whereas symmetry around copper(II) metal in complex 5 is confirmed by three different g values (g 1 , 2.095; g 2 , 2.15; g 3 , 2.26), which supports rhombic distortion. The value of g ‖ obtained is greater than g ⊥, which is greater than g e, in 1 – 4 , 6 is in well agreement in d x2-y2 ground term of square planar geometry. The value of empirical factor f for complexes 1 – 4, 6 lies in the range, 102–135 cm indicating a square planar geometry with small distortion, where as in complex 5 value (f = 146 cm) is in conformity of tetrahedral geometry with larger distortion. All the compounds (selenosemicabazones and their complexes) are tested for DPPH radical scavenging, ABTS radical scavenging, FRAP ferric reducing and CUPRAC cupric reducing antioxidant capacity assay and all the compounds have shown good antioxidant capacity in general. Best results are obtained for H1L with FRAP, 6.75 ± 0.01 μg TE/ml and CUPRAC, 9.52 ± 0.07 μg TE/ml. All the compounds are also tested for their anti-tubercular activity against M. tuberculosis H37RV strain ATCC27294. Ligands, H1L , H3L , H6L and complex 6 have shown highest anti-TB activity (MIC = 1.6 µg/ml) which is similar to the standard drugs (Isoniazid, Ethambutol). anti-TB activity of H2L and H5L (MIC = 12.5 µg/ml and 25 µg/ml) increased on complexation with copper(II) (MIC = 1.6 µg/ml, 2 ; 12.5 µg/ml, 6). Experimental results are supported by molecular modeling studies, where a considerable intermolecular interaction of these compounds with the active site of amino acid of enoyl reductase from M. tuberculosis has been observed with minimum binding energy −6.2, −7.3, −7.7, −7.4, −7.2, −8.7 Kcal/mol for H1L , H2L , H3L , H4L , H5L , and H6L and −7.2, −9.4, −8.6, −9.3, −9.9, and −10.6 Kcal/mol for copper complexes 1, 2, 3, 4, 5 and 6 exhibited respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • New Cu(II) and Zn(II) complexes with polynitrogen Schiff bases were synthesized. • Mutual arrangement of N atoms in the ligand affects the structure of the complex. • Complexes showed better antibacterial and antifungal activities than the ligands. • The strongest activity was observed against E. coli for complexes with L2. Reactions of copper(II) and zinc(II) acetates with polynitrogen Schiff bases, namely 4-(pyridin-2-yl)methyleneamino-1,2,4-triazole (L1), 4-(pyridin-3-yl)methyleneamino-1,2,4-triazole (L2) and 4-(pyridin-4-yl)methyleneamino-1,2,4-triazole (L3), were studied. The reaction of Zn(OAc) 2 ·2H 2 O and L1 gave crystals of trinuclear complex [Zn 3 (OAc) 6 (L1) 2 ] (1). A similar reaction of Zn(OAc) 2 ·2H 2 O and L2 resulted in 1D coordination polymer [Zn(OAc) 2 (L2)] n (2). The reactions of Cu(OAc) 2 ·H 2 O with L2 or L3 gave crystals of 1D coordination polymer {[Cu 2 (OAc) 4 (L2)]·2MeCN} n (3) and binuclear complex [Cu 2 (OAc) 2 (L3) 2 ]·2MeCN (4), respectively. The structures of the coordination compounds thus obtained were determined by single-crystal X-ray diffraction analysis. Complexes 1 – 4 demonstrated better antibacterial and antifungal activities in comparison with free L1, L2, and L3 ligands: the strongest antimicrobial activity was observed against E. coli for 2 and 3 , and the highest antifungal activity was found for 1 and 2. [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., (© 2023. The Author(s).)

The synthesis and characterization of three new bis (1,4,7-triazacyclononane) ligands, L 1 , L 2 and L 3 , featuring a bridging guanidinium group between two macrocyclic units, is reported. The corresponding binuclear copper(II) complexes have been studied as agents to accelerate the cleavage of P–O bonds within two model phosphodiesters, namely bis ( p -nitrophenyl)phosphate (BNPP) and 2-hydroxypropyl- p -nitrophenylphosphate (HPNPP). The results of a comparative study of cleavage rates, using the mononuclear copper(II)–tacn complexes bearing single alkylguanidinium groups as a reference, revealed that the binuclear copper(II) complexes are generally less effective cleavage agents, which may be related to a tendency to form hydrolytically inactive hydroxo-bridged species at near-neutral pH and above. However, at pH 7, these complexes produced 4–18-fold increases in the rate of BNPP hydrolysis compared to the parent complex, [Cu(tacn)(OH 2 ) 2 ] 2+ . Likewise, at pH 6, the complexes cleaved HPNP 5–130-fold faster than [Cu(tacn)(OH 2 ) 2 ] 2+ , suggesting some degree of cooperative interplay between the two proximal copper(II) centers and the protonated guanidinium bridging group in promoting phosphodiester hydrolysis under these conditions. [ABSTRACT FROM AUTHOR]

In order to evaluate the influence of substitution on biological properties of Schiff bases and their metal complexes, a series of differently substituted fluorine-containing Schiff bases starting from the drug isoniazid (isonicotinylhydrazide) were prepared and their structures were established by single-crystal X-ray diffraction. Also, four copper(II) complexes of these Schiff bases were synthesized. The prepared compounds were evaluated for their antimicrobial activity and urease inhibition. Two of the Schiff bases exerted activity against C. albicans. All copper(II) complexes showed excellent inhibitory properties against jack bean urease, considerably better than that of the standard inhibitor acetohydroxamic acid. [ABSTRACT FROM AUTHOR]

In this work we present the speciation of the ternary complexes formed between the copper(II)-salicylate (Sal 2 − ) system and the small blood serum bioligands, such as lactate (Lac − ), oxalate (Ox 2 − ), citrate (Cit 3 − ) and phosphate (PO 4 3 − ). The speciation of the ternary systems were studied by pH-potentiometry at 25 °C and using an ionic strength I = 1.0 mol·dm − 3 KNO 3 . In the Cu(II)-Sal 2 − − Lac − system the complexes [Cu(Sal)(Lac)(OH)] 2 − , [Cu(Sal)(Lac)(OH) 2 ] 3 − and [Cu(Sal) 2 (Lac)] 3 − were detected. In the case of the Cu(II)-Sal 2 − –Ox 2 − system the complexes [Cu(Sal)(Ox)] 2 − , [Cu(Sal)(Ox)(OH)] 3 − and [Cu(Sal)(Ox)(OH) 2 ] 4 − were observed. In the Cu(II)-Sal 2 − − Cit 3 − system the species [Cu(Sal)(H 2 Cit)] − , [Cu(Sal)(HCit)] 2 − , [Cu(Sal)(Cit)] 3 − and [Cu(Sal)(Cit)(OH)] 4 − were detected and in the Cu(II)-Sal 2 − –PO 4 3 − system the complexes [Cu(Sal)(H 2 PO 4 )] − , [Cu(Sal)(HPO 4 )] 2 − and [Cu(Sal)(PO 4 )] 3 − were observed. [ABSTRACT FROM AUTHOR]

In this study, the N, N, O metal chelator 2-pyridinecarboxaldehydeisonicotinoyl hydrazone (HPCIH, 1) and its derivatives 2-acetylpyridine-(HAPIH 2), 2-pyridineformamide-(HPAmIH, 3) and pyrazineformamide-(HPzAmIH, 4) were employed in the synthesis of four copper(II) complexes, [Cu(HPCIH)Cl]·0.4HO ( 5), [Cu(HAPIH)Cl]·1.25HO ( 6), [Cu(HPAmIH)Cl]·HO ( 7) and [Cu(HPzAmIH)Cl]·1.25HO ( 8). The compounds were assayed for their action toward Mycobacterium tuberculosis H37Rv ATCC 27294 strain and the human tumor cell lines OVCAR-8 (ovarian cancer), SF-295 (glioblastoma multiforme) and HCT-116 (colon adenocarcinoma). All copper(II) complexes were more effective in reducing growth of HCT-116 and SF-295 cells than the respective free hydrazones at 5 µg/mL, whereas only complex 7 was more cytotoxic toward OVCAR-8 lines than its ligand HPAmIH. 6 proved to be cytotoxic at submicromolar doses, whose IC values (0.39-0.86 µM) are similar to those ones found for doxorubicin (0.23-0.43 µM). Complexes 5 and 6 displayed high activity against M. tuberculosis (MIC = 0.85 and 1.58 µM, respectively), as compared with isoniazid (MIC = 2.27 µM), which suggests the compounds are attractive candidates as antitubercular drugs. [ABSTRACT FROM AUTHOR]

The infrared and electronic absorption spectra of a series of new heteroleptic chelated copper (II) complexes [Cu(diamine)(acac)]X that encompass N,N′-1,6-bis(2-bromophenyl)-2,5-diazahexane (diamine), acetylacetonate (acac) and ClO4-, BPh4-, PF6- and BF4-(X) were studied. The IR, electronic absorption spectra and the molar conductivity of the newly prepared complexes were presented and discussed. The molar conductivity in dichloromethane reveals a predominance of electrostatic interactions between [Cu(diamine)(acac)]+ entity and anions, X- that counterbalance the positive charge. The resulting complexes with local symmetry of CuO2N2 attain a square-coplanar structure and exhibit the tendency for axial ligation, which is enhanced when an electron-attracting substituent is attached to the phenyl ring of diamine moiety. The tendency for axial ligation is particularly fulfilled when suitable nucleophiles (solvents) with different donor abilities exist, leading to solvatochromism. The solute-solvent interactions are revealed by shifts in the ligand field absorption spectra that are enhanced as the donor power of the solvent increases. Linear dependence of the ligand field absorption maximum on solvent donor number is generally observed.

In this work, we describe the immobilization of the dinuclear compound [Cu2(apyhist)2Cl2](ClO4)2 (1) and its derived cations complexes, obtained in water solution or by deprotonation of the imidazolate moiety in the ligand leading to a cyclic tetranuclear species, in the Nafion® membrane on glass carbon electrode surface. After that, we studied the influence of the equilibrium in the electrocatalytic activity towards the reduction of H2O2 in the development of an amperometric sensor for the analytical determination of hydrogen peroxide. This strategy proved successful, and the electrochemical behaviour of the all complexes formed within the Nafion® coatings was characterized. We also provide evidence that its related cyclic tetranuclear imidazolate-bridged complex acts as a catalysts for the intramolecular, two-electron reduction of H2O2.

Two new mixed-ligand complexes of formula [Cu(mal)(abpt)(H2O)].3/2H2O (1) and [Cu2(sq)(abpt)2].2H2O (2) [mal = malonate, abpt = 4-amino-3,5-di-2-pyridyl-4H-1,2,4 triazole and sq = squarate], have been prepared and characterized by X-ray crystal structure determination and magnetic studies. Complex 1 crystallizes in the monoclinic system, space group C2/c, with a = 14.0086(2) Å, b = 10.0980(2) Å, c = 25.630(4) Å; β = 97.5900(10) o, and Z = 8. Complex 2 crystallizes in the triclinic system, space group P-1 with a = 7.5696(15) Å, b = 8.4697(17) Å, c = 11.049(2) Å; β = 93.00(3)o, α = 96.98(3), γ = 90.111(3) and Z = 1. Complex 1 consist of a neutral mononuclear [Cu(mal)(abpt)(H2O)] unit and water molecule of crystallization in a distorted square pyramidal coordination sphere, while complex 2 is viewed as being made up of [Cu(sq)(abpt)2] units with the squarato ligand bridging the two copper(II) cations. Variable temperature magnetic behaviour of the complexes reveals the existence of weak antiferromagnetic interaction for complex 1 and weak ferromagnetic intrachain interaction for complex 2.

Mononuclear copper(II) and nickel(II) complexes of the formulae [Cu(L1)] (1), [Ni(L1)] (2), [Cu(L2)] (3) and [Cu(L3)H2O] (4) (where L1 = N,N’-ethylenebis(4,6-dimethoxysalicylidenaminato), L2 = N,N’-ethylenebis(5-bromosalicylidenaminato) and L3 = N,N’-ethylenebis(5-bromo-3-methoxysalicylidenaminato)) were synthesized as microcrystalline powders and characterized by IR spectroscopy, thermal analysis and magnetic measurements. The magnetic susceptibility of the Cu(II) complexes changed with temperature according to the Curie-Weiss law. The complexes 1, 3 and 4 exhibit magnetic moments of 2.29, 2.20 and 1.88 µB, respectively, at 303 K. These values practically do not change with lowering the temperature to 77 K. The nickel(II) complex 2 is diamagnetic.

The current study reports the synthesis of copper complexes of a tridentate Schiff base ligand. The compounds of the type [Cu(L)X]∙n(H2O) (where L = tridentate ONN Schiff base ligand, X = Cl−, Br−, SCN−, NO3−, CH3COO−), were characterized on the basis of elemental analyses, FT-IR, UV-vis, molar conductance, 1H-NMR, XRD and thermal analyses. The spectra revealed that the Schiff base ligand acts as a tridentate ligand through two azomethine nitrogen atoms and a phenolic oxygen atom. The molar conductance measurements of the complexes in DMF correspond to non-electrolytic nature. TGA and DTA studies results gave insight into the dehydration, thermal stability, and thermal decomposition. Square-planar geometry has been assigned to the prepared complexes as indicated by the electronic spectral measurements. Cu(II) compounds showed antiradical potential against DPPH and ABTS radicals. The antimicrobial potential of the Schiff base ligand and its Cu(II) complexes were evaluated by the rapid p-iodonitrotetrazolium chloride (INT) colorimetric assay against some selected bacteria strains: Staphylococcus aureus and Enterococcus faecalis (Gram +ve); Klebsiella pneumoniae and Pseudomonas aeruginosa (Gram −ve), and fungi (Candida albicans and Cryptococcus neoformans). The compounds showed a broad spectrum of antibacterial and antifungal activities, with MIC values ranging from 48.83 to 3125 μg/mL.

X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments.

In coordination compounds studies, a knowledge of the magnitude of the stability constants of complexes is necessary for preliminary quantitative treatment. Described herein is a method that involves the use of advanced ionophoretic technique for the study of the equilibria in binary complex systems in solution. This method is based upon the migration of a spot of the metal ion on a paper strip at different pH values of background electrolyte containing 0.1 M perchloric acid and 0.01 M norvaline. A graph of pH against mobility provides information about the nature of the complexation and helps in calculating stability constants. Using this method, the stability constants of binary complexes metal(II) – norvaline have been determined to be (8.11 ± 0.02, 7.03 ± 0.09); (3.77 ± 0.11, 2.39 ± 0.07) and (7.59 ± 0.05, 6.17 ± 0.04) (log K values) for Cu(II), Mn(II) and UO2(II) complexes, respectively, at 35 ºC.