Thermodynamics of Copper(II) Complexes of Diamino Diamides in Aqueous Solution

The equilibria occurring in aqueous solutions of N,N′-bis(β-carbamoylethyl)ethylenediamine, N,N′-bis(β-carbamoylethyl)trimethylenediamine, N,N′-bis(β-carbamoylethyl)-1,2-propylenediamine, and N,N′-bis(β-carbamoylethyl)-2-hydroxytrimethylenediamine with protons and copper(II) ions as well as the deprotonation reactions of the copper (II) complexes of these four ligands have been studied by calorimetry at T=25.0°C and I=0.10 mol dm^?3 (NaClO₄). The enthalpy changes and the entropy changes for these reactions are reported and discussed.     

Effects of Ring Size on Spectral Properties of Copper(II)-Diaminodiamide Complexes in Aqueous Solution

The electronic absorption spectra of aqueous solutions containing copper(II) ion and N, N′-bis(carbamoylmethyl)trimethylenediamine(L-1, 3, 1) at 25.0 ± 0.1°C and 0.10 mol L^?1 NaClO₄, were measured as a function of pH. The absorption maxima and the molar absorptivities of [Cu(L-l, 3, l)]²⁺, [Cu(H.₁L-1, 3, 1)]⁺, and [Cu(H_-2L-l, 3, l)] were calculated from these spectra. A comparison of the spectral parameters of these complexes with those of the copper(lI)-diaminodiamide complexes containing 6, 5, 6-and 6, 6, 6-membered ring systems indicates that the chelate ring size has significant effects on these spectral parameters.     

Transition metal complexes of furfural and benzil schiff bases derived from S-benzyldithiocarbazate

New nickel(II), copper(II), cobalt(III) and rohdium(III) complexes of two Schiff base ligands formed by condensation of furfural and benzil with S-benzyldithiocarbazate have been synthesized and characterized by elemental analysis and magnetic and spectroscopic measurements. The nickel(II) complexes, Ni(NS)₂ and Ni(ONS)₂ (NS and ONS stand for the uninegatively charged furfural and benzil Schiff bases, respectively) are square-planar and octahedral, respectively. The Cu(NS)Cl complex is paramagnetic with a magnetic moment fo 1.73 B.M. A halogen-bridged dimeric structure is proposed for this complex. The copper(II) complex, Cu(ONS)Cl is diamagnetic, suggesting strong antiferromagnetic interactions between a pair of copper(II) ions in a thiolo sulphur-bridged dimeric or polymeric structure. Cobalt(II) ions are oxidized in the presence of the Schiff bases with the concomitant formation of cobalt(III) complexes of empirical formulae, Co(NS)₃, Co(ONS)₂ClO₄ and Co(ONS)₂Cl, respectively, which are spin-paired and octahedral. The rhodium(III) complex of the furfural Schiff base, Rh(NS)₂Cl is tentatively assigned a halogen-bridged dimeric structre.     

Magnetic Properties and Mössbauer Spectra of Binuclear Copper(II) and Tetranuclear Diiron(III)-porphyrin-dicopper(II) Complexes with Schiff-Base Ligands of 2-lmidazolealdehyde and Acetylpyrazine

The binuclear copper(II) and tetranuclear diiron(III)-porphyrin-dicopper(II) complexes with the Schiff-base ligands of N,N′-bis(2-imidazolaldehyde)ethylenediimine, N,N′-bis(2-imidazolaldehyde)-p-phenyldiimine, N,N-bis(acetylpyrazine)-ethylenediimine and N,N′-bis(acetylpyrazine)-p-phenyldiimine have been prepared and characterized. The magnetic data indicated that the spin ground states and the magneic interaction between Cu(II)-Cu(II) or Fe(III)-Cu(II) are dependent on the nature of the bridging ligands. A weak antiferromagnetic interaction between Fe(III) and Cu(II) is evident from the temperature-dependent magnetic measurements. The Mössbauer spectra of iron(III) -porphyrin sites showed an asymmetric quadrupole doublet consistent with high-spin iron(III) S = 5/2.     

The copper(II) complexes with tetradentate Schiff base ligands: Synthesis, crystal structures, and computational studies

Mononuclear copper(II) Schiff base complexes, Cu(BrSal₂Pn) (I) and Cu(BrSal₂MePn) (II), where BrSal₂Pn = N,N′-bis(5-bromo-2-hydroxybenzylidene)propane-1,3-diamine and BrSal₂MePn = N,N′-bis(5-bromo-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine, have been synthesized and characterized by elemental analyses and single-crystal X-ray diffraction. Also, the optimized geometries of them have been calculated using density functional theory method (B3LYP/6–31g). Obtained structural parameters are in agreement with the experimental data. The geometry around the copper atoms display a distorted square-planner structure by coordinating with two oxygen atoms from the phenols moieties and two nitrogen atoms from the imino groups of ligands and thus established three 6-membered rings.     

Multiply charged ions of ruthenium(II), rhodium(III) and cobalt(III) complexes in electrospray ionization mass spectrometry

Multiply charged ions from electrospray ionization (ESI) were observed for ruthenium-bidentate ligand complexes, such as [RuL₂B]X₂ and [(RuL₂)₂B]X₄, where L is 2,2′-bipyridine, B are tetradentate ligands of 2,2′-bis(2′-pyridyl)bibenzimidazole and 2,6-bis(2′-pyridyl)benzodiimidazole, bidentate ligand of 2-(2′-pyridyl)benzimidazole and related compounds and X is CIO₄^- or CI^-. ESI mass spectra showed a simple mass pattern for easy structural assignment and detecting impurities. The mass spectra for binuclear complexes provide a charge state distribution ranging from 4+ to 2+ for Ru(II)—Ru(II) compounds and 5+ to 2+ for Ru(II)—Rh(III) compounds. It was found that different multiply charged ions are generated by loss of counterions and by protonation/deprotonation at the proton site of ligands B. The abundances of these ions are qualitatively explained in terms of the acidity of metal complexes depending on the bridging ligand structures and the charge of the metal ions. Ions produced by removal of ligands were hardly observed.     

Studies on novel unsymmetrical azomethines—III : Copper(II) complexes of unsymmetrical tetradentate azomethines

Copper(II) complexes of unsymmetrical bifunctional tetradentate azomethines having the general formulae, (OC₁₀H₆CH:NXN:C(R)C₆H₄O)Cu, (OC₁₀H₆CH:NXN:C(CH₃)CHC(CH₃)OCu, (OC₆H₄CH:NXN:C(CH₃)C₆H₄O)Cu, (OC₆H₄C(R);NXN:C(CH₃)CHC(CH₃)O)Cu (where R = H or CH₃, X = (CH₂)₃, (CH₂)₄, (CH₂)₆ or -oC₆H₄) have been synthesized by the reactions of preformed mixed imine complexes of the type, CuLL′ (where L and L′ are two different imines such as 2-hydroxy-1-naphthaldimine, salicylaldimine, o-hydroxyacetophenonimine or acetylacetonimine) with diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane or o-phenylenediamine. These complexes have been characterized by elemental analyses, TLC, conductance, magnetic measurements, IR and electronic spectra.     

Two copper(II) complexes of curcumin derivatives: synthesis,crystal structure and in vitro antitumor activity

Two Cu(II) complexes of curcumin derivatives, formulated as CuL ₂ ^a (1) and CuL ₂ ^b (2) [HL^a = 1,7-bis(4-ethyloxy-3-methoxy-phenyl)-1,6-heptadiene-3,5-dione and HL^b = 1,7-bis(4-butyloxy-3-methoxy-phenyl)-1,6-heptadiene-3,5-dione], have been synthesized and characterized by single-crystal X-ray diffraction, along with physicochemical and spectroscopic methods. In both complexes, each Cu(II) center is surrounded by four oxygen atoms from two β-diketone ligands in a square planar geometry. Complex 1 forms a 2D layer structure through intermolecular π–π stacking interactions, as well as weak coordination interactions between the Cu and O atoms of the solvent 1,4-dioxane molecules. Complex 2 displays a 1D column structure stabilized by intermolecular π–π stacking interactions. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays were used to evaluate the cytotoxicities of these complexes against three human cancer cell lines. The results show that the Cu(II) complexes exhibit more potent inhibition tumor growth in comparison with the free ligands.     

Binuclear Copper(II) Complexes in which other copper(II) complexes are coordinated as bidentate ligands

Twelve new copper(II) complexes in which N,N′-bis-(2-pyridylmethyl)-oxamidatocopper(II) or N,N′-bis(2-pyridylethyl)-oxamidatocopper(II) coordinates as a bidentate ligand have been isolated and characterized. These complexes have a structure bridged by the oxamide group (including two tetranuclear complexes formed by olation of two binuclear complexes, of. Fig. 1), and possess Cu? Cu interaction resulting in a sub-normal magnetic moment at room temperature. In one of them, [Cu₂(PMoxd) (bipy)₂] (NO₃)₂ (cf. Fig. 2), each copper(II) ion has a five-coordinated environment.     

An N2O2 Tetradentate Ligand 6,6′-Bis(Acylamino)-2,2′-Bipyridine. Oxidation-Reduction Properties of Cobalt Complexes

Abstract

Recently, we reported the syntheses and the properties of a new type of N₂O₂ tetradentate ligands, 6,6′-bis(acylamino)-2,2′-bipyridines and their copper(II) complexes. ¹. These ligands form two different types of square-planar complexes, i.e., Type 1 and Type 2, depending on the pH of the solution. ^1,2 In addition, the deprotonated complexes (Type 2) are suggested to have strong ligand field, and are regarded as analogues of salen complexes. In this paper, we report syntheses and properties of cobalt complexes of 6,6′-bis(benzoylamino)-2,2′-bipyridine (babpH₂), and the interaction of the Type 2 complex with molecular oxygen.     

Studies on Co(II) and Cu(II) complexes of a ligand derived from 1,3-phenylenediamine and 5-bromosalicylaldehyde synthesis, characterisation, thermal properties and use as new precursors for preparation cobalt and copper oxide nano-particles

A symmetric tetradentate Schiff base ligand, N,N′-bis(5-bromosalicylaldehyde)-1,3-phenylenediamine [(Brsal)₂-1,3-phen) and its Cu(II) and Co(II) complexes with general formula M₂((Brsal)₂-1,3-phen)₂, where M=Co (1) and Cu (2)], have been synthesized and characterized by elemental analyses and FTIR spectroscopy. In addition, Schiff base ligand has been characterized by ¹HNMR spectroscopy. Thermogravimetric analysis of the ligand and its metal complexes reveals their thermal stability and decomposition pattern.     

Synthesis,characterization, and histological activity of novel polydentate azo ligands and their cobalt(II), copper(II) and nickel(II) complexes

We describe the synthesis and characterization of two novel azo ligands, 4,5-dihydroxy-3,6-bis(2-hydroxyphenylazo)-2,7 naphthalene disulfonic acid (H₂L) and 4,5-dihydroxy-3,6-bis(2-hydroxy-4-sulfophenylazo)-2,7-naphthalenedisulfonic acid (H₂L¹). The Cu(II), Ni(II), and Co(II) complexes of these ligands were prepared and characterized by infrared, UV–Vis, ¹H- and ¹³C-NMR spectra, atomic absorption spectroscopy, mass spectrometry, elemental analyses, thermogravimetric analysis, conductivity, cyclic voltammetry, and magnetic measurements. The results suggest that the complexes have a 2:1 (metal:ligand) molar ratio, involving binuclear azo ligands with an ONO donor set. Metal ion uptake studies were conducted with a batch technique. Preliminary histological studies were also made. The results indicate that the azo ligands have high thermal stability, good metal extraction capacity, and favorable dying properties with certain tissues.     

Dinuclear Nickel(II) and Zinc(II) Complexes of 2,6-[N,N′-bis(2-hydroxyphenylmethyl)-N,N′-bis(2-pyridylmethyl)aminomethyl]-4-methylphenol

Abstract

The symmetric 'end-off' compartmental proligand 2,6-[N,N′-bis(2-hydroxy-phenylmethyl)-N,N′-bis(2-pyridylmethyl)aminomethyl]-4-methylphenol (H₃L) has been used to generate homodinuclear nickel(II) and zinc(II) complexes. The crystal structures of the complexes reveal that the di-nickel(II) complex is donor asymmetric and the di-zinc(II) complex is coordination number asymmetric. In both complexes non-coordinated acetic acid molecules are tightly hydrogen-bonded to the pendant phenols of the ligand generating a double acid salt of the type[CH₃COO…H…L…H…OOCCH₃]^3? in the dinickel complex and a single acid salt of the type [CH₃COO…H…L]^3? in the dizinc complex. In both cases the ligand periphery has been extended to provide a supraligand in which the donor potential of the original ligand has been enhanced.     

Synthesis of Substituted 4,4′-Oxy-bis(aminophenylglyoximes) and Their Polymeric Metal Complexes with Cu(II), Ni(II), and Co(II) Salts

4,4′-Bis(chloroacetyl)diphenyl ether (HL) was synthesized from chloroacetyl chloride and diphenyl ether in the presence of AlCl₃ as catalyst by Friedel-Crafts reaction. Subsequently, its keto oxime (H₂L) and glyoxime (H₄L) derivatives were also prepared. Then, five new substituted 4,4′-oxy-bis(aminophenyl-glyoximes) (H₄L_1–5) were synthesized from 4,4′-oxy-bis(chlorophenylglyoxime) and the corresponding amines. The Ni(II), Cu(II), and Co(II) complexes of these ligands were prepared. The structures of these ligands and their complexes were identified by FT-IR, ¹H NMR, and ICP-AES spectral data, elemental analyses, and magnetic measurements.     

Synthesis, characterization, crystal structure and antimicrobial activities of new transN,N-substituted macrocyclic dioxocyclam and their copper(II) and nickel(II) complexes

New trans-disubstituted macrocyclic ligands, 1,8-[N,N-bis(3-formyl-12-hydroxy-5-methyl)benzyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L¹), 1,8-[N,N-bis(3-formyl-12-hydroxy-5-bromo)benzyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L²), N,N-bis[1,8-dibenzoyl]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L³), N,N-bis[1,8-(2-nitrobenzoyl)]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L⁴), and N,N-bis[1,8-(4-nitrobenzoyl)]-5,12-dioxo-1,4,8,11-tetraazacyclotetradecane (L⁵) were synthesized. The ligands were characterized by elemental analysis, FT IR, ¹H NMR and mass spectrometry studies. The crystal structure of L¹ is also reported. The copper(II) and nickel(II) complexes of these ligands were prepared and characterized by elemental analysis, FT IR, UV-Vis and mass spectral studies. The cyclic voltammogram of the complexes of ligand L^1-3 show one-electron quasi-reversible reduction wave in the region −0.65 to −1.13 V, whereas that of L⁴ and L⁵ show two quasi-reversible reduction peaks. Nickel(II) complexes show one electron quasi-reversible oxidation wave at a positive potential in the range +0.95 to +1.06 V. The ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry with nuclear hyperfine spin 3/2. All copper(II) complexes show a normal room temperature magnetic moment value μ_eff 1.70-1.73 BM which is close to the spin only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalysts were carried out. The ligands and their complexes were also screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi.     

Synthesis, characterization, electrochemical studies, and antibacterial activities of cobalt(III) complexes with Salpn-Tipe Schiff base ligands. Crystal structure of trans-[CoIII(L1)(Py)2]ClO4

The synthesis, characterization, spectroscopic and electrochemical properties of trans-[Co^III(L¹)(Py)₂]ClO₄ (I) and trans-[Co^III(L²)(Py)₂]ClO₄ (II) complexes, where H₂L¹ = N,N′-bis(5-chloro-2-hydroxybenzylidene)-1,3-propylenediamine and H₂L² = N,N′-bis(5-bromo-2-hydroxybenzylidene)-1,3-propylenediamine, have been investigated. Both complexes have been characterized by elemental analysis, FT-IR, UV-Vis, and ¹H NMR spectroscopy. The crystal structure of I has been determined by X-ray diffraction. The coordination geometry around cobalt(III) ion is best described as a distorted octahedron. The electrochemical studies of these complexes revealed that the first reduction process corresponding to Co(III/II) is electrochemically irreversible accompanied by dissociation of the axial Co-N(Py) bonds. The in vitro antimicrobial activity of the Schiff bse ligands and their corrsponding complexes have been tested against human pathogenic bacterias such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli. The cobalt(III) complexes showed lower antimicrobial activity than the free Schiff base ligands.     

Synthesis,spectral characterization,anticancer and antibacterial studies of cyclodiphosph(V)azane derivatives and their copper(II) complexes

The new cyclodiphosph(V)azane derivatives (1,3-dimethyl-2,4-dioxo-2',4'-bis(2,4-bis(dimethylaminopropylimino)cyclodiphosph(V)azane (H₂L¹) (1,3-dimethyl-2,4-dioxo-2',4'-bis(2,4-bis(dimethylaminoethylimino)cyclodiphosph(V)azane (H₂L²) and (1,3-dimethyl-2,4-dioxo-2'-(dimethylaminoethylimino)-4'-(dimethylaminopropyl-imino)cyclodiphosph(V)azane (H₂L³) containing four active coordination centers (NNNN) and their Cu(II) complexes have been synthesized and characterized by elemental analyses, spectroscopic methods, molar conductance as well as thermal and magnetic measurements. The UV–Vis and mass spectra of the ligands and their Cu(II) complexes were also recorded. The copper(II) complexes were found to have magnetic moments of 1.58–1.69 B. M. corresponding to one unpaired electron. The possible geometries of the complexes were assigned on the basis of EPR, electronic, and infrared spectral studies. The absence of water molecules in all complexes was supported by thermal studies. All the thermal decomposition processes ended with the formation of CuO. The kinetic and thermodynamic parameters have been calculated. The ligand (H₂L³) and its Cu(II) complexes were screened for their anticancer studies against human breast cancer cell lines MCF-7 and minimum inhibitory concentration was calculated. The screening was extended to the antibacterial activity using Kirby–Bauer single disk susceptibility test for all compounds.     

Metallkomplexe von Farbstoffen. VIII Übergangsmetallkomplexe des Curcumins und seiner Derivate

Metal Complexes of Dyes. IX. Transition Metal Complexes of Curcumin and Derivatives The bidentate monoanions of curcumin[CU, (1, 7-bis(4-hydroxy-3-methoxyphenyl)-hepta-1,6-diene-3,5-dione)], diacetylcurcumin[DACU, (1,7-bis(4-acetyl-3-methoxyphenyl)-hepta-1,6-diene-3,5-dione)], dihydroxycurcumin[DHCU, (1,7-bis(4-hydroxiphenyl)-hepta-1,6-diene-3,5-dione)], dimethylcurcumin [DMCU, (1,7-bis(3,4-dimethoxyphenyl)-hepta-1, 6-diene-3,5-dione)] and trimethylcurcumin[TMCU, (1,7-bis(3,4-dimethoxyphenyl)-4-methylhepta-1,6-diene-3,5-dione)] form with chloro bridged complexes [(R₃P)MCl₂]₂ (M?Pd, Pt; R?phenyl, n-butyl, ethyl, tolyl), [η⁵-C₅Me₅)MCl₂]₂ (M?Rh, Ir), [(η⁶-p-cymene)RuCl₂]₂, [(η³-C₃H₅)PdCl]₂, di-μ-chlorobis[N-(diphenylmethylene)-glycinethylester-(C,N)]-dipalladium(II) and with [(η⁵-C₅Me₅)Co(CO)I₂] monochelate dye complexes. The structure of [(η⁶-p-cymene)(Cl)Ru(DMCU)] was determined by X-ray diffraction. The dichelates (DMCU)₂M with M?Cu, Ni, (CU)₂Pd and the trichelate (CU)₃Fe were obtained. Cationic bipyridine copper(II) complexes with CU, DHCU, and DMCU were sythesized by treating the dye ligands with copper(II) acetate, 2,2′-bipyridine and ammoniumtetrafluoroborate. In comparison to the free 1.3-diketones the dye complexes show a bathochromic shift in the UV/VIS spectra.     

Copper(II)-lanthanoid(III)-copper(II) trinuclear complexes with N,N′-bis(2-aminopropyl)-oxamido ligand

Six novel μ-oxamido trinuclear complexes, namely Cu₂(oxap)₂Ln(ClO₄)₃ (Ln: La, Pr, Nd, Gd, Yb, Ho), where oxap is N,N′-bis(2-aminopropyl)oxamido, have been synthesized. The complex Cu₂(oxap)₂Gd(ClO₄)₃ was characterized with variable temperature magnetic susceptibility (4—300 K). The exchange integrals J (Cu—Gd) and J′ (Cu–Cu) were found to be 0.83 cm^?1 and ?1.62 cm^?1, indicating that very weakly ferromagnetic spin-exchange interaction operates between Cu(II) and Gd (III) ions.     

Complexation between decamethyl-3,3′-bis(dipyrrolylmethene) and zinc(II), copper(II), and cobalt(II) acetates

Decamethyl-3,3′-bis(dipyrrolylmethene) dihydrobromide H₂L · 2HBr (H₂L is bis(3,4,7,8,9-pentamethylpyrrol-3-yl)methane), which is the simplest representative of a novel class of oligo(dipyrrolylmethenes) belonging to chromophore chelating nonmacrocyclic ligands, were examined by ¹H NMR, IR, and electronic absorption spectroscopy. Complexation reactions of H₂L · 2HBr with M(AcO)₂ (M = Zn(II), Cu(II), and Co(II)) in DMF at 298.15 K were monitored by electronic absorption spectroscopy and studied by the molar ratio method. The thermodynamic constants K ⁰ of these reactions were estimated. The d metal ions coordinate H₂L to give the binuclear homoleptic complexes [M₂L₂]. The reactions proceed through the intermediate binuclear heteroleptic complex [M₂L(AcO)₂] detected by spectroscopic methods. The thermodynamic stabilities of [M₂L₂] and [M₂L(AcO)₂] increase when moving from Cu(II) to Zn(II) and Co(II). The probability of formation and stability of [M₂L₂] containing 3,3′-bis(dipyrrolylmethene) are substantially higher than those of analogous complexes with the 2,2′-isomer (decamethyl-2,2′-biladienea, c). The low K ⁰ values for the complexation between H₂L and Cu(AcO)₂ are due to slow oxidation of the biladiene ligand into a bilatriene with participation of Cu²⁺ ions.