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Copper(II) complexes of sulfonamides have found importance in biological and pharmaceutical systems. This study focuses on copper(II) complexes that were synthesized by precipitation method. The spectroscopic characterization was done by different techniques like FT-IR, UV–Vis, and ESI-MS. Compound 6 [Cu(L2)]2·2DMSO [HL = 4-((naphthalene-1-sulfonamido)methyl)cyclohexanecarboxylic acid] was recrystallized from DMSO, and its structure was determined by single-crystal X-ray diffraction to confirm the results of the synthesis of series of compounds. The geometry around each Cu(II) is tetrahedral bipyramidal with monodentate DMSO at the apical and bidentate carboxylates in the equatorial positions and a Cu–Cu bond. The synthetic compounds were screened for their biological applications involving antibacterial (Escherichia coli [E.C], Staphylococcus aureus [S.A], Sheigella sonnei [S.S], Bacillus subtilis [B.S], Nesseria gonorrhoeae [N.G], and Chromohalobacter israelensis [C.I]), antifungal (Aspergillus niger [A.N] and Neurospora crassa [N.C]), enzyme inhibition (acetylcholinesterase [AChE] and butyrylcholinesterase [BChE]), and antioxidant study. Furthermore, molecular docking study of all compounds was performed against enzymes and DNA using AutoDock Tools version 1.5.6. After confirmation of DNA-interaction through docking studies, nuclease activity was performed using agarose gel electrophoresis method and all compounds have been found to cleave DNA. These results concluded that copper complexes of sulfonamide may be good induction in the future for medical purposes. [ABSTRACT FROM AUTHOR]

Two water-soluble dicationic complexes, [Cu(bipy)(dipn)](BF4)2 (1) and [Cu(bipy)(dipn)](NO3)2 (2) (bipy = 2.2-bipyridine and dipn= dipropylenetriamine), were synthesized in high yields. The desired complexes were characterized by CHN-EA, UV-Vis, SEM, EDS, FTIR, TGA, and XRD. The single-crystal XRD of [Cu(bipy)(dipn)](BF4)2 reflected that Cu(II) complex is formed in a distorted square pyramid configuration. The Hirshfeld surface analysis (HSA) confirmed more powerful atom-atom interaction, the hydrogen bonding in H...F, supporting the outcome of XRD. The influences of the CTDNA/complexes were gathered by viscosity, CV, and electronic absorption measurements. The estimated binding constants (Kb) for 1 and 2 were 4.5×104 and 3.4×104 M-1, respectively. Complex 2 revealed slightly poorer DNA binding capability than 1. Eventually, the molecular docking of [Cu(bipy)(dipn)]+2 species was evaluated and demonstrated employing 1BNA-DNA segment. [ABSTRACT FROM AUTHOR]

The hydrazones of nonsteroidal anti-inflammatory drugs (NSAIDs) diclofenac and ibuprofen are synthesized with aldehydes of pyridine and imidazole and are characterized by ¹H, 13C and mass spectroscopy. Cu(II) complexes of hydrazones constructed from these ligands possess square planar geometry for bidentate diclofenac-hydrazone and tridentate ibuprofen-hydrazone conjugates with [Cu(L)2] and [Cu(L)Cl] compositions, respectively. The observed irreversible Cu(II)/Cu(I) redox couple in the range of +0.20 to +0.61 V is due to the substantial distortion in the square-planar geometry. ESR studies indicate the appreciably covalent character within M-L bonding due to extensive delocalization of electron from dx--y 2 2 orbital. The hydrazone-NSAID conjugates exhibit substantial cytotoxicity against A-549, HCT-116 and MDA-MB-231 cancer cell lines with ibuprofen-imidazolehydrazone ligand possessing the lowest IC50 (2.26 μM) amongst the synthesized NSAID-conjugates. Interestingly, its Cu(II) complex also displays excellent anticancer activity against MDA-MB-231 with IC50 value of 3.58 μM. Such a feature may be ascribed to the synergistic association of Cu(II)-NSAID-hydrazone linkage. Thus, conjugation of NSAID with hydrazone and its complexation with a bioactive metal ion may be regarded as a potential strategy for designing of non-platinum anticancer agents. [ABSTRACT FROM AUTHOR]

In present study, we have synthesized two homologous series of some new Schiff base of 4-n-alkoxy-2-hydroxy benzaldehyde (n = 2–8, 10, 12, 14, 16, 18) with 4-amino acetanilide and their corresponding Cu(II) complexes. A series of new Schiff base containing two aromatic rings have been synthesized and characterized by various spectroanalytical techniques including FT-IR and 1H NMR. The mesomorphic properties of these compounds were observed by optical polarized light microscopy (POM) and confirmed by differential scanning calorimetry (DSC) study. It has been observed that all the newly synthesized compounds exhibit wide range SmA phase. [ABSTRACT FROM AUTHOR]

Comprehensive mole-ratio, kinetic, EPR and X-ray studies were performed to investigate substitution reactions between square-planar [CuCl2(en)] (en = ethylenediamine) and square-pyramidal [CuCl2(terpy)] (terpy = 2,2':6',2"-terpyridine) complexes with bio-relevant nucleophiles at 295 K in 0.010 M Tris-HCl buffer (pH = 7.4) in the presence of 0.010 M NaCl. According to mole-ratio and EPR studies, Tris buffer reacts with [CuCl2(en)], and likely the complex geometry remains square-planar. Kinetic results have shown that the order of reactivity of nucleophiles towards [CuCl2(en)] in solution for both reaction steps is 1,2,4-triazole > imidazole > pyrazine. The order of reactivity of the azole and diazine ligands toward [CuCl2(terpy)] for the first reaction step is imidazole > 1,2,4-triazole > pyrazine, while for the second one is pyrazine > 1,2,4-triazole > imidazole. X-ray studies indicate great affinity of ethylenediamine toward Cu(II), which results in crystal structures of [Cu(en)2]Cl2·H2O and [Cu(en)2][ZnCl4], instead of dinuclear or heteronuclear complexes with a bridging pyrazine ligand. The recorded EPR spectra demonstrate that all ligands interact with Cu(II) complexes, except in the case of the [CuCl2(en)] complex, where the competition between ligand and Tris molecules might be observed. [ABSTRACT FROM AUTHOR]

Interactions of copper(II) complexes which contain S-alkyl derivatives of thiosalicylic acid (alkyl = methyl, ethyl, propyl and butyl; aryl = benzyl), marked as 1–5, with guanosine-5′-monophosphate (5′-GMP) and calf thymus DNA (CT-DNA) were studied. Kinetics of substitution reactions of 1–5 with 5′-GMP and CT-DNA were investigated under pseudo-first-order conditions at 310 K and pH = 7.2 in 25 mM Hepes buffer using stopped-flow method. All complexes have high affinity toward studied bio-molecules. Additionally, interactions with CT-DNA were followed by absorption spectroscopy and fluorescence quenching measurements. The results indicate that complexes bind to DNA exhibiting high binding constants (Kb = 104 M−1). During the examination of competitive reactions with ethidium bromide (EB), results showed that complexes can replace EB-bound DNA. In addition, a new crystal structure of the binuclear Cu(II) complex with S-substituted thiosalicylate derivative has been reported. In the present series of Cu(II) complexes the crystal structure is the first example of a complex comprising an S-aryl derivative of thiosalicylate ligand. Through comparative study of structural properties of six molecules from four crystal structures we examined the structural variations, potentially important for biological activity of these complexes. [ABSTRACT FROM AUTHOR]

Four new mononuclear copper(II) complexes with methyl acetoacetate and benzoylacetone in the presence of 1,10-phenanthroline and 2,2′-bipyridine were synthesized and characterized by elemental analyses, FT-IR, and UV-Vis spectroscopy. The molecular structures of complexes [Cu(MAA)(bpy)(ClO4)] (1a), [Cu(bzac)(bpy)]ClO4 (2a), [Cu(MAA)(phen)(ClO4)] (1b) and [Cu(bzac)(phen)(ClO4)] (2b) were determined by single crystal X-ray diffraction technique. 1a, 1b, and 2b are five coordinate with a distorted square pyramidal geometry and the structure of 2a consists of isolated [Cu(bzac)(bpy)]+ cations and perchlorate counter anions. The electrochemical studies of copper complexes in acetonitrile solution showed that CuII/CuI reduction processes are electrochemically irreversible. Cytotoxic activity of complexes was screened, including an MTT assay against gastric cancer cell line (MKN-45). The four Cu(II) complexes exhibited lethal effects against MKN-45 cell lines and the half maximal inhibitory concentration (IC50) values obtained were much lower in comparison with 5-fluorouracil. In addition, MTT and migration studies revealed that benzoylacetone complexes are more active than complexes of methyl acetoacetate against the MKN-45 cancer cell lines. Docking simulations of Cu(II) complexes on DNA revealed that the most stable adducts with DNA bind in the minor groove. All complexes display a binding specificity to the A/T rich regions. [ABSTRACT FROM AUTHOR]

The advantage of capillary electrophoresis was demonstrated for studying a complicated system owing to the dependence of direction and velocity of the electrophoretic movement on the charge of complex species. The stability constants of copper(II) complexes with ions of succinic acid were determined by capillary electrophoresis, including the 1 : 2 metal to ligand complexes which are rarely mentioned. The measurements were carried out at 25 °C and ionic strength of 0.1, obtained by mixing the solutions of succinic acid and lithium hydroxide up to pH 4.2–6.2. It was shown that while pH was more than 4.5 the zone of copper(II) complexes with succinate moves as an anion. It is impossible to treat this fact using only the complexes with a metal-ligand ratio of 1 : 1 (CuL0, CuHL+). The following values of stability constants were obtained: logβ(CuL) = 2.89 ± 0.02, logβ(CuHL+) = 5.4 ± 0.5, logβ(CuL22−) = 3.88 ± 0.05, logβ(CuHL2−) = 7.2 ± 0.3. [ABSTRACT FROM AUTHOR]

This article reports the detailed study concerning the mode of binding of three forms of vitamin B6, pyridoxamine (pm), pyridoxine (pn), and pyridoxal (pl), with Cu(II) in aqueous solutions using three independent methods: potentiometry, conductometry, and UV–vis spectroscopy. The stability constants of complexes formed between copper(II) and vitamin B6were investigated by potentiometric titration in 0.1 M KNO3ionic medium at 25 °C. While drawing the relations between molar conductance and the ratio of metal to ligand concentrations, different types of lines were obtained indicating the formation of 1 : 1 and 1 : 2 stoichiometric compounds. The stability constants have been determined using EQUID and CVEQUID computer programs and the obtained results were in agreement. The relatively high values of stability constants of Cu(II)-vitamin B6complexes obtained from three independent methods in comparison to those with other competing cations suggest that the complexes studied are relatively stable in aqueous solutions. [ABSTRACT FROM PUBLISHER]

Two series of new Cu(II) complexes derived from the reaction of copper acetate with the non-linear 1,2,3-triazole-based Schiff bases have successfully been synthesised. The structures of the ligands and its complexes were elucidated by elemental analysis, FT-IR,1H-NMR and UV–visible spectroscopic techniques. The differential scanning calorimetry and polarizing optical microscopy supported the anisotropic properties of uncoordinated ligands in which the focal conic fan-shaped texture and/or broken fan-shaped texture characteristics of respective SmA and SmC phases were recorded. However, not all of their corresponding Cu(II) complexes are mesogenic. Although the iodo-substituted ligands with even parity C10H29to C14H33are non-stable and exhibit SmA phase which is not reproducible, the ultimate Cu(II) complexes show exclusively stable SmA phase. This observation can be ascribed to the enhanced colinearity and molecular anisotropic by the presence of Cu-N and Cu-O coordination modes. On the other hand, the comparison studies show that different positions ofortho-hydroxyl group affect the mesomorphic and thermal behaviour of ligands and Cu(II) complexes. [ABSTRACT FROM AUTHOR]

Some new Cu(II) complexes containing [1,2,3]-triazole-based bidentate salicylaldimine and its analogues with terminal substituent (F, Cl, Br and I) have been synthesieed. All the target complexes and their uncoordinated ligands were elucidated by elemental analysis and spectroscopic techniques (UV-visible, FT-IR, 1D, 2D1H and13C-NMR). The polarising optical microscope and differential scanning calorimetry (DSC) have disclosed all complexes and ligands are mesomorphic except the complex without any terminal substituent. The fluoro-substituted complexes with even parity C14H29and C16H33exhibit new enantiotropic nematic phase which was absent in their corresponding ligands, whereas the suppression of SmC phase occurred for all complexes with longer C16H33and C18H37. X-ray diffraction confirmed the existence of SmA, SmC and N phases for complexes and ligands. The other notable feature is that the self-ordering of terminal alkyl chain occurred in SmA and SmC phases of complexes with even terminal alkyl chain ranging from C14H29to C18H33. Their corresponding ligands exhibit intercalated structure of SmA and SmC phases. The thermal behaviour studies show that the fluoro-substituted triazole-based complexes possess lowest phase transition temperature and more stable as compared to other substituent which decomposed during the isotropisation. [ABSTRACT FROM PUBLISHER]

Self-assemblies of the 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) and Cu(OH)2in the presence of dicarboxylate ligands yielded four new complexes, [Cu4(bpca)4(L1)2(H2O)2]·5H2O (1), [Cu2(bpca)2(L2)(H2O)2]·2H2O (2), [Cu2(bpca)2(L3)(H2O)2]·H2O (3), and [Cu2(bpca)2(L4)(H2O)2]·3H2O (4) (bpca = bis(2-pyridylcarbonyl)amide anion, H2L1 = phthalic acid, H2L2 = succinic acid, H2L3 = maleic acid, H2L4 = acetylenedicarboxylic acid). Their structures were determined by single-crystal X-ray diffraction analyzes and further characterized by IR spectra and thermogravimetric analyzes. The five-coordinate Cu ions in1are bridged by phthalate to form 1-D chains, which are assembled into 3-D frameworks by extensive hydrogen bonds. Compounds2–4possess similar structures, built up of [Cu2(bpca)2(L)(H2O)2] (L = L2 for2, L3 for3, L4 for4) and lattice molecules. The 3-D frameworks of2–4are completed by hydrogen bond interactions. [ABSTRACT FROM PUBLISHER]

Series of symmetrical liquid crystal dimers wherein the spacer connected to two mesogenic units of salicylideneimines consists of the aliphatic chain -(CH2)n- where n adopts even parity numbers from 2 to 10 have been synthesized and characterized. These dimers function as tetradentate ligands which possess strong affinity toward the Cu(II) ion leading to the formation of four-coordinated complexes with Cu-N and Cu-O modes. The uncoordinated dimers exhibit enantiotropic nematic as well as smectic C phases. However, the Cu(II) complexes behave predominantly as nematogens. Correlation study between the effect of variable spacer length and the mesomophic behaviors of these dimers along with their related Cu(II) complexes are reported. The Cu(II) complexes in which the ligands possess shorter spacers were seemed to exhibit higher thermal stability. [ABSTRACT FROM AUTHOR]

Cu(II) complexes having distorted square pyramidal geometry with N2SO donor azo–thioether ligand, [Cu(L)X] (X = Cl (1) and Br (2)), have been synthesized and characterized. The geometries of the complexes are confirmed by single crystal X-ray analysis. The complexes form supramolecular 1D chains by intermolecular H-bonding and?–?interaction between the pyridines. Spectral and electrochemical properties have been studied. Electronic structure and spectral properties are explained by DFT and TDDFT analysis. [ABSTRACT FROM PUBLISHER]

In aqueous methanolic solution, reactions of CuCl2,m-hydroxybenzoic acid (HL), and NaOH with 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) at room temperature afforded {[Cu(bpy)L](µ2?Cl)(µ2?L)[Cu(bpy)L]}?1.2H2O (1) and {[Cu(phen)Cl](µ2?Cl)(µ2?L)[Cu(phen)L]} (2) with chloro- and carboxylato-bridged dinuclear [Cu(µ2?Cl)(µ2?COO)Cu] cores. The Cu2dimers in1are pairwise aggregated to form H-bonded tetranuclear motifs, which are extended by H2O into 1-D H-bonded chains and further assembled into 2-D supramolecular networks. The Cu2dimers in2are also linked into 1-D H-bonded chains and further assembled into 2-D supramolecular layers. Magnetic measurements indicate that significant antiferromagnetic interactions (J = ?15.9, ?12.2 cm?1) between Cu2+ions are dominant in these dinuclear [Cu(µ2?Cl)(µ2?COO)Cu] cores. To the best of our knowledge,2, crystallizing in the acentric polar orthorhombic space groupPna21, represents the first example of metalm-hydroxybenzoato complexes with ferroelectric properties with a remnant polarization (Pr) of ca. 0.04?µC cm?2, coercive field (Ec) of ca. 2.52 kV cm?1, and saturation of the spontaneous polarization (Ps) at ca. 0.195?µC cm?2. [ABSTRACT FROM PUBLISHER]

Pyrazolone derivatives (Z)-4-((2-hydroxyethylimino)(p-tolyl)methyl)-3-methyl-1 -phenyl-1 H-pyrazol-5(4H)-one [PMP-EA] (1), (Z)-L-(3-chlorophenyl)-4-((2-hydroxyethylimino)(p-tolyl)methyl)-3-methy 1-1 H-pyrazol-5(4H)-one [MCPMP-EA] (2), and (Z)-4-((2-hydroxyethylimino)P-tolyl)methyl)-3-methyl-l-p-tolyl-l W-pyrazol-5(4H)-one [PTPMP-EA] (3) have been synthesized and character-ized. The molecular geometry of 2 has been determined by single-crystal X-ray study. These ligands exist in amine-one tautomeric form in the solid state. Three copper(II) complexes, [Cu (PMP-EA)(H20)2] (4), [Cu(MCPMP-EA)(H20)2] (5), and [CU(PTPMP-EA)(H20)2] (6), respec-tively, have been synthesized using these ligands and characterized by microanalytical data, molar conductivity, IR, UV-Visible, FAB-Mass, magnetic measurement, TG-DTA studies, and ESR spec-tral studies; Cu(II) is five-coordinated with [ML(H20)2] composition. The interaction of the com-plexes with CT-DNA (calfthymus) was investigated using different methods. The results suggest that the copper complexes bind to DNA via intercalation and can quench the fluorescence intensity of EB bound to DNA. [ABSTRACT FROM AUTHOR]

Cu(II) complexes with Schiff bases DMIIMP, DMIIMBD, DMIIMBP, DMIIMCP, DMIIMMP, and DMIIMNP (see Introduction for definitions) are derived from condensation of 3,4-dimethyl 5-amino-isoxazole with salicylaldehyde and substituted salicylaldehydes. The newly synthesized ligands were characterized by IR, UV-Vis,1H NMR,13C NMR, mass spectra, and elemental analysis. The Cu(II) complexes were characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, thermogram, DTA, and single crystal analysis. The complexes have general formula [M(L)2]. The Schiff bases are bidentate coordinating through the azomethine nitrogen and phenolic oxygen of salicylaldehydes. Based on the analytical and spectral data, four-coordinate geometry is assigned for all the complexes. ESR and single crystal analysis suggests square planar geometry for all complexes. [Cu(DMIIMP)2] crystallizes in the orthorhombic system. Antimicrobial studies of Schiff bases and their metal complexes show significant activity with the metal complexes showing more activity than corresponding Schiff bases. Cytotoxicity of the copper complexes on human cervical carcinoma cells (HeLa) was measured using the Methyl Thiazole Tetrazolium assay. [ABSTRACT FROM AUTHOR]

A new homologous series of bidentate Schiff bases 5-alkoxy-2-((4-(phenyldiazenyl) phenylimino)methyl)phenol and their Cu(II) complexes have been synthesized and characterized by spectroscopic techniques along with studies on the mesomorphic properties. Phase transitions of all the Schiff bases and Cu(II) complexes in this series are enantiotropic. The ligands with n-octyloxy and n-decyloxy flexible chains exhibit the nematic (N) and smectic A (SmA) phases, the latter of which is characterized by focal conic fan-shaped texture. In contrast, the Cu(II) complexes show exclusively the SmA phase, which is ascribed to the presence of Cu‒O and Cu‒N coordination modes. For the same reason, the thermal stabilities of the complexes have also been improved. [ABSTRACT FROM PUBLISHER]

The C-pivot tripodal ligands 1,1,1-tris(4-(2-benzimidazole)-2-oxa-butyl)propane(L1), 1,1,1-tris(4-(2-benzimidazole)-2-oxa-butyl)ethane(L2) and their picrate Copper (II) complexes, with the composition [CuL1](pic)2·H2O(1) and [CuL2](pic)2·H2O (2) (pic = picrate), were synthesized and characterized by elemental analysis, conductivity measurements, IR spectra, UV spectra, and electrochemical. The interaction of these complexes with calf thymus DNA were investigated by UV absorption spectroscopy, fluorescence spectroscopy, and viscosity measurements. The experimental results suggest that the two complexes bind to DNA via an intercalation binding mode. [ABSTRACT FROM AUTHOR]

The formation of Cu(II) complexes with 1-alkyl-4-methylimidazoles (where alkyl = butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl) has been studied by using the liquid-liquid partition method at 25°C and a fixed ionic strength of the aqueous phase (I = 0.5; (HL)NO3, KNO3). 2-Ethylhexanol, dichloromethane, chloroform, p-xylene, and toluene were used as a solvent. Stability constants, βn, of the complexes in aqueous solution were determined as well as their partition ratios between the organic and aqueous phase. Under the influence of the steric effect, the methyl group in position 4 as well as the length of the alkyl group in position 1 of the ligands and electron-donating properties of solvents, both the polyhedral structure and the co-ordination numbers of the Cu(II) complexes are changed, thus resulting in an increase in the solvent/water partition ratios, Pn, of the complexes and lowering of the pH1/2 of the extraction. [ABSTRACT FROM AUTHOR]

Two temperature-dependent Cu(II) compounds, [Cu(mpdaH)2(H2O)4] · 4H2O (1) and [Cu(mpdaH)2]n (2) (H2mpda = 2,6-dimethylpyridine-3,5-dicarboxylic acid), have been synthesized under hydrothermal conditions and characterized by X-ray single crystal diffraction, elemental analysis, thermogravimetric analyses, and IR spectra. The structure at room temperature confirms that 1 is mononuclear with the octahedral coordination geometry. However, on warming to 120°C the same reaction gives 2, in which copper(II) has square planar coordination and is further bridged by mpdaH- ligands to form extended 2-D layers with parallelogram-like (4,4) topology. Furthermore, in both complexes, through π-π stacking and hydrogen bonding interactions, 3-D supramolecular networks are assembled. [ABSTRACT FROM AUTHOR]

Formation of Cu(II) complexes of 1,2-dialkylmidazoles (where 1-alkyl = ethyl, propyl, butyl, pentyl, and hexyl, and 2-alkyl = propyl, butyl, and pentyl) has been studied using the liquid-liquid partition method, at 25°C and at a fixed ionic strength of the aqueous phase (I = 0.5; (HL)NO3, KNO3). The complexes were extracted with 2-ethyl-1-hexanol, and chloroform. The length of the 1-alkyl, and 2-alkyl groups, and the solvent nature have been shown to influence the extraction process. Extraction curves (log DM vs. pH) are displaced towards lower pH with increasing chain length of the 1-alkyl and 2-alkyl substituents. Stability constants of the complexes in aqueous solution as well as their partition constants between the aqueous and organic phase were determined. The stability of the Cu(II) complexes increased with increasing 1-alkyl chain length. The stability constants were comparable with βn values for the Cu(II) complexes of 1-alkyl-2-ethylimidazoles, but smaller than those of the Cu(II) - 1-alkylimidazole counterparts. The length of the 2-alkyl substituent has been found to affect both the pH1/2 values and the partition constants of the complexes. The partition constants P1 are small for all of the 1,2-dialkylimidazole complexes with Cu(II), whereas P2 and P3 are high and they increase with elongation of the 1-alkyl chain owing to a decrease in the co-ordination number of Cu(II), probably from 6 to 4 at the second and third complexation step. This change is likely to produce square coplanar species, readily extractable with organic solvent. This finding offers the possibility of extraction of the Cu(II) ions from a mixture cations. [ABSTRACT FROM AUTHOR]

The chelating behavior of some hydrazones towards Cu(II) has been investigated. The isolated complexes were characterized by elemental analysis, magnetic moment, spectra (electronic, IR and ms) and thermal measurements. The IR spectra showed that the ligands are deprotonated in the complexes as bidentate, tridentate and binegative tridentate. Protonation constants of the ligands and the stability constants of their Cu(II) complexes were calculated. Square-planar, square-pyramidal, tetrahedral and/or distorted octahedral structures are proposed. The TGA data help to confirm the chemical formula of the complexes and indicated the steps of their thermal degradations. [ABSTRACT FROM AUTHOR]

The synthesis of the macrocyclic ligand 4,4'-(2,6,10,13,18-pentaaza26)-2,2'-bipyridylcylophane (L), which contains a penta-amine chain linking the 4,4' positions of a 2,2'-bipyridyl moiety, is reported. The heteroaromatic nitrogens of L are located outside the macrocyclic cavity. Ligand protonation, as well as Cu(II) and Ni(II) complexation by L, were studied by potentiometric and UV-Vis techniques in aqueous solution. Only mononuclear complexes are formed. In [CuL]2+, the metal is encapsulated inside the cavity, not coordinated by the bipyridyl unit. Protonation of the complex occurs on the aliphatic polyamine chain and gives rise to translocation of the metal outside the cavity, bound to the heteroaromatic nitrogens. Conversely, Ni(II) is always bound to the bipyridyl nitrogens in both protonated and unprotonated complexes. [ABSTRACT FROM AUTHOR]

A Cu(II) complex of 2-benzylmercapto-5-methyl-1,3,4-thiadiazole was synthesized and characterized. The crystal structure of the copper complex and the free ligand were determined by single-crystal X-ray diffraction at room temperature: {[Cu(C10H10N2S2)2(Cl)2], P1 triclinic, a = 8.1450(2) Å, b = 8.1690(2) Å, c = 10.8180(3) Å, α = 97.4040(12)°, β = 101.6270(11)°, γ = 116.1431(14)°; C10H10N2S2 ligand, Pbca orthorhombic, a = 8.7938(7) Å, b = 9.6491(7) Å, c = 25.3552(18) Å}. The metal complex framework consists of discrete units that provide crystalline stability through a network of van der Waals contacts. The Cu(II) is coordinated by two chloride ions and two 2-benzylmercapto-5-methyl-1,3,4-thiadiazole monodentate ligands showing a distorted square planar configuration. Both thiadiazole ligands coordinate through the N atom bonded to the benzylthio substituted C atom. The FTIR spectroscopic data are consistent with this structural model. Analysis of the magnetic susceptibility from 5 K to room temperature indicates the presence of paramagnetic Cu(II), confirmed by the EPR spectrum. [ABSTRACT FROM AUTHOR]

Dipeptides glycyl-L-serine and L-seryl-L-tyrosine are tridentate ligands in coordination with Cu(II) through their NH2-, N-(from deprotonated amide group) and O-atom (by COO- group), forming [CuII(LH-1)H2O]. The forth position of square-planar geometry of Cu2+ is occupied by H2O as terminal ligand. Solid-state linear dichroic IR-spectroscopy, UV-Vis, mass spectrometry with ESI and FAB, tandem mass spectrometry (HPLC-MS/MS), TGV and DSC methods, EPR and magnetochemistry data prove the formation of five-membered chelate rings with participation of Cu2+ both in solution and in solid state. [ABSTRACT FROM AUTHOR]

Formation of Cu(II) complexes of 1-alkyl-2-ethylimidazoles (where alkyl=propyl, butyl, pentyl, hexyl, and octyl) has been studied by using the liquid-liquid partition method, at 25°C and a fixed ionic strength of the aqueous phase (I=0.5; (HL)NO3, KNO3). The complexes were extracted with 2-pentanone, 2-butanol, isoamyl alcohol, 2-ethyl-1-hexanol, dichloromethane, trichloromethane, and toluene. The length of the 1-alkyl group and the nature of solvent have been shown to influence the extraction process. Extraction curves (log DM vs. pH) are displaced towards lower pH's with increasing chain length of the 1-alkyl substituent and donor number of the solvents. Stability constants of the complexes in aqueous solution were determined as well as their partition ratios between the aqueous and organic phase. The stability of the Cu(II) complexes increased with increasing 1-alkyl chain length. The stability constants are comparable with βn ones for the Cu(II) complexes of 1-alkyl-2-methylimidazoles, but smaller than those of the Cu(II)-1-alkylimidazole counterparts. The Pc-partition ratios of the 1-alkyl-2-ethylimidazole complexes with Cu(II) are high, and increased with increasing 1-alkyl chain length and the donor number of the solvents. Both the strong steric effect of the ethyl substituent at position 2 and the bulkiness of the 1-alkyl-2-ethylimidazole molecules as well as the strong electron-donating properties of the solvent molecules have an effect on the change of the coordination number of Cu(II) from 6 to 4. The 4-coordinate Cu(II) complexes (distorted tetrahedron) are more readily extractable by organic solvent than are the 6-coordinate ones and for this reason their partition constants, Pc, are high. This finding offers the possibility of extraction of the Cu(II) ions from a mixture cations. [ABSTRACT FROM AUTHOR]

By using the liquid-liquid partition method, the formation of Cu(II) complexes with 1-alkyl-2-methylimidazoles (where alkyl=isobutyl, pentyl, isopentyl, hexyl, octyl, decyl, and dodecyl) has been studied at 25°C and at fixed ionic strength of the aqueous phase (I=0.5; (HL)NO3, KNO3). The complexes were extracted with 2-ethyl-1-hexanol, dichloromethane, trichloromethane and, in one system only, toluene. Stability constants of the complexes in aqueous solution as well as partition constants of the extractable species were determined. It has been shown that the stability constants are invariable and do not depend on the 1-alkyl chain length. The constants were smaller than those of the previously studied Cu(II) - 1-alkylimidazole complexes owing to the steric effect of the methyl group at position 2. The partition constants of the complexes incereased with increasing alkyl chain length. Branched 1-alkyl substituents (isobutyl, isopentyl) suppressed both stability constants and the partition constants of the complexes. [ABSTRACT FROM AUTHOR]

Two novel Cu(II) complexes, [Cu(H2tpda)(acac)](ClO4)0.5Cl0.5 · H2O, [Cu(H2tpda)(NO3)]ClO4 (2) (H2tpda = tripyridyldiamine) have been synthesized, and characterized by X-ray analyses, elemental analyses, IR, UV and ESR spectra. Single crystal X-ray diffraction revealed that the Cu atom in complex 1 is coordinated to three N atoms from H2tpda and two oxygen atoms from acac with an approximately trigonal bipyramidal geometry. The molecules are assembled through intermolecular hydrogen bonds and π-π stacking, affording a two dimensional network. In complex 2, the Cu atom is coordinated with three N atoms from H2tpda and two oxygen atoms from [image omitted] in addition to a weak coordination with one oxygen from [image omitted], resulting in an irregular octahedral environment, and the molecules are also connected by intermolecular hydrogen bonding and π-π stacking, affording a one dimensional structure. [ABSTRACT FROM AUTHOR]

The partition of Cu(II) complexes with 1-alkylimidazoles (with alkyl ranging from 1-n-butyl through 1-n-hexadecyl) between the aqueous ((0.5HL, K)NO3) and organic phase has been studied at 25°C. The organic solvents used were toluene, p-xylene, tetrahydronaphthalene, dichloromethane, 2-ethyl-1-hexanol, and others. Extraction curves have been shown to be displaced towards lower pH values with increasing alkyl chain length of the alkyl substituent. Stability constants of the Cu(II) complexes with the 1-alkylimidazoles have been determined in the aqueous phase as well as the number of compounds extractable into the organic solvent, and their partition ratios. Stability constants of the complexes did not depend on the alkyl chain length. One or two complexes were transferred to the organic phase. Partition ratios of these complexes, P1 and P2, increased rapidly with increasing alkyl chain length. They were higher in magnitude than those of their Co(II), Ni(II), and Zn(II) counterparts. [ABSTRACT FROM AUTHOR]

Heterobinuclear metal chelates of Mn 2+ , Co 2+ or Cu 2+ and some transition metal ions with o -cresolphthalein complexone have been prepared and characterized. Elemental analyses are in agreement with proposed formulae. Thermal analyses (TGA and DTA) were used to determine the degradation products; some thermodynamic parameters were calculated. IR and UV-Vis spectra identified the mode of bonding between the metal ions and the ligand as well as its geometry. Magnetic moment determination and ESR spectra of the heterobinuclear complex revealed some antiferromagnetic interaction between the metal ions, which depends mainly on the two metal ions forming the chelate. Electrochemical studies of the complexes [DC-polarography and cyclic voltammetry (CV)] confirmed the existence and the nature of the metal ions in the chelate. [ABSTRACT FROM AUTHOR]

Copper (II) complexes of the type [Cu(BMS) 2 ], [Cu(PTA) 2 ] and [Cu(BMS)L(H 2 O) x ( x =2 or 0)] where BMSH=bis(benzoylmethyl) sulfide and L=8-hydroxyquinoline (oxineH)/salicylaldehyde (salH)/salicylaldoxime (saloH)/salicylaldehydephenylhydrazone (salphH)/acetylacetone (acacH)/phenylthioacetophenone (PTAH) and also the mixed-ligand complexes of Cu(II) with PTAH and oxineH have been synthesized and characterized. [ABSTRACT FROM AUTHOR]