Ternary mixed-ligand complexes of copper(II) with α-aminoalkylphosphonic acids and amino acids

Formation of ternary mixed-ligand complexes of copper (II) with 16 -amino acids and -aminophosphonic acids (APA) with a 111 ratio of initial concentrations has been studied by potentiometric titration at 25C and 0.1 M KC1 in aqueous solution. The complexes Cu_pA_nB_sH_q are formed in solution, where A and B are the deprotonated ligands. The stability of the mixed-ligand complexes (log ) increases and the equilibrium is displaced more towards their formation (log K) as the hydrophobic nature of the ligands increases.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 570–575, March, 1991.     

Enantio- and chemoselective differentiation of protected α-amino acids and β-homoamino acids with a single copper(II) host

The association between an achiral copper(II)-containing host 1 and chiral carboxylates has been expanded beyond previous studies to new chiral carboxylate guests, both α-amino acids and β-homoamino acids. The observed exciton-coupled circular dichroism (ECCD) signals for the enantiomers of each carboxylate were equal and opposite, and these signals differed in size and shape between the individual amino acids. Linear discriminant analysis (LDA) was applied as a statistical analysis technique to differentiate the amino acids, both enantioselectively and chemoselectively, giving the absolute configuration and identity of the amino acid. The identity of each of the α-amino acids and β-homoamino acids were determined independently by LDA, and then the two were considered together. Each of these analyses showed good differentiation of the amino acid guests with the use of only one host molecule.     

Extraction of copper(II) ions from ammonia solutions with a β-diketone extractant

The extraction of copper(II) ions from ammonia solutions with a new β-diketone extractant, DX-510A, has been studied. Kinetic features of the copper(II) extraction and back extraction have been established: the reaction orders have been determined, and extraction and stripping rate constants have been calculated to be k_e1 = 4.14 × 10^–2 s^–1 and k_be1 = 3.20 × 10^–2 s^–1, respectively. It has been demonstrated that the extraction of copper(II) ions is not accompanied by the coextraction of ammonia. The type of extracted complex has been determined and its formula has been suggested.     

Transesterification of copper(II) β-ketoesterates and acylpyruvates with borneol

Transesterification of copper(II) acetoacetates, copper(II) trifluoroacetoacetate, and copper(II) acylpyruvates with borneol gives the copper(II) chelates of the corresponding bornyl esters in 92–95 % yields. Bornyl acetyl- and perfluoroacylpyruvates were synthesized for the first time by decomposing the respective chelates with hydrogen chloride. Bornyl acylpyruvates react with hydrazine hydrate to give 5-alkyl-3-bornyloxycarbonylpyrazoles.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 902–904, May, 1993.     

Complexes of Cu(II) with 2,2′-dipyridyl and some malonic acids

The stability constants of ternary complexes containing copper(II), 2,2′-dipyridyl and a set of mono- and di-substituted malonic acids, were obtained by potentiometric titrations. The results are discussed in terms of substituent influences upon the chelation of the malonic dianions to the system Cu(dip). It is suggested that the electronic and geometric characteristics of the strongest ligand, govern the coordination of the second one.     

Synthesis,characterization and biological activity of copper(II) complexes with ligands derived from β-amino acids

Transition Metal Chemistry - Two copper(II) complexes with ligands derived from β-amino acids, 2-(1-aminocyclohexyl)acetic acid L1 and 2-(1-amino-4-(tert-butyl)cyclohexyl)acetic acid L2, were...     

Complexes of copper(II) with the β-blocker atenolol

Mono- and binuclear copper(II) complexes with atenolol (HAt) can be obtained, depending on the reaction conditions. The mononuclear violet complex cation has the general formula Cu(HAt)₄ ²⁺ with an elongated octahedral geometry. The two ligands in the equatorial plane are bound in a bidentate fashion through the hydroxyl oxygen and amino nitrogen, while the other two atenolol molecules in axial position are coordinated in a monodentate way. The binuclear green complex Cu₂At₂Cl₂, is neutral, where atenolol acts as a bidentate (O^–, NH) bridging ligand. The bridge between the two Cu atoms is realized by the deprotonated oxygen of the alcohol group.     

Release control of fragrances by complexation with β-cyclodextrin and its derivatives

The release control of fragrances, benzyl acetate (BA), citral (CR), linalool (LL), citronellol (CL) and linalyl acetate (LA), was conducted using β-cyclodextrin (β-CyD), 2-hydroxypropyl-β-CyD (HP-β-CyD) and 2,6-di-O-methyl β-CyD (DM-β-CyD). The release rate of the fragrances from 30% ethanol/water solution was significantly suppressed by the complexation with these CyDs, and the suppressing effect increased in the order of β-CyD?<?HP-β-CyD?<?DM-β-CyD. The concentration-dependent change of the release rate was quantitatively analyzed to obtain the stability constant (Kc) of the fragrance-CyD complexes. These Kc values were in good agreement with those determined by the solubility method. The results suggest that the release of fragrances can be prolonged by the complexation with β-CyDs and their effects can be controlled by choosing appropriate CyD derivatives with higher Kc values and by setting proper concentrations of the host molecules.     

Extraction and complexation of copper(II) with para-tert-butylbenzhydrazide and its N′,N′-dimethyl derivative

The extraction of copper(II) with the para-tert-butylbenzoic acid hydrazide and related N??,N??-dimethyl derivative was studied. The composition and structure of the extracted complexes were determined, the mechanism of extraction of copper(II) in different media was suggested, the extraction constant was calculated. The copper(II) complex compounds with these reagents were isolated.     

Complex formation of nitrobenzoic acids and some naphthalene derivatives withβ-cyclodextrin

Host-guest complexation of benzoic acid, its nitro-derivatives, 1- and 2-naphthols and 1- and 2-naphthylamines with-cyclodextrin have been investigated by a spectrophotometric method. Formation constants for both the conjugate acid and base forms have been determined. Only in the case of 4-nitrobenzoic acid, is a more stable complex formed with the ionic species, compared with the undissociated one, supporting the assumption that resonance charge delocalisation and London dispersion interactions are responsible for their stability. With naphthalene derivatives, the 2-isomers give more stable complexes indicating deeper penetration into the cyclodextrin cavity.     

Complexes of copper(II) with sugar α-amino acids as ligands

Summary Complexes of Cu^II with 2-(benzylamino)-2-deoxy-d-glycero-d-talo heptonic acid (BnMa) and 2-(benzylamino)-2-deoxy-d-glycero-l-gluco heptonic acid (BnGa) were prepared and characterized by elemental analysis, thermal data, i.r., electronic and e.s.r. spectra, magnetic susceptibility measurements, and X-ray powder diffraction. The metal:ligand stoichiometry of these complexes is 12 and coordination around Cu^II seems to be octahedral, with the ligands bound through the N atom of the amino group and O atoms of the bridging carboxylate group.     

Potentiometric investigation of ternary complexes of nickel(II), zinc(II) and cadmium(II) ions with β-alaninehydroxamic acid and ethylenediamine

Summary The formation constants of mixed ligand complexes of M^II (M = Ni, Zn or Cd) with -alaninehydroxamic acid (-Alaha) as primary ligand (A) and ethylenediamine (en) as secondary ligand (B) have been determined potentiometrically [298 K, = 0.2 (KCl)]. The formation constants for binary systems of -alaninehydroxamic acid and ethylenediamine were determined under identical experimental conditions. The pH-titration data were analysed using the SUPERQUAD computer program. The relative stability of each ternary complex was compared to that of its corresponding binary complex in terms of log X values.     

Structure and thermal properties of volatile copper(II) complexes with β-diimine derivatives of acetylacetone and the structure of 2-(methylamino)-4-(methylimino)-pentene-2 crystals

Copper(II) chelates with β-diimine derivatives of acetylacetone that have a general formula of Cu(R¹C(NR²)CHC(NR²)R¹)₂, where R¹, R² are alkyl substituents, are synthesized. The complexes were identified using elemental analysis, melting point measurements, and high-temperature mass spectrometry data. Knudsen technique is employed to determine the vapor pressure temperature dependence, and standard thermodynamic parameters of sublimation ΔH _T ⁰ and ΔS _T ⁰ are derived. A single crystal X-ray diffraction study is carried out for copper(II) complexes of Cu(CH₃-C(NCH₃)-CH-C(NCH³)-CH₃)₂ (a = 10.363(1) Å, b = 11.978(1) Å, c = 12.653(1) Å, V = 1570.6(3) ų, space group Pnc2, Z = 4, d _calc = 1.328 g/cm³, R = 0.027), Cu(CH₃-C(NC₂H₅)-CH-C(NC₂H₅)-CH₃)₂ (a = 11.782(4) Å, b = 13.951(8) Å, c = 25.591(8) Å, V = 4206(3) ų, space group C222¹, Z = 8, d _calc = 1.169 g/cm³, R = 0.10), and also 2-(methylamino)-4-(methylimino)-pentene-2 CH₃-(C=(NCH₃))-CH=(C-(NHCH₃))-CH₃ (a = 12.129(2) Å, b = 12.034(2) Å, c = 5.692(1) Å, β = 107.05(3)°, V = 794.3(3) ų, space group Cc, Z = 4, d _calc = 1.055 g/cm³, R = 0.06). Van der Waals lattice energy E _cryst is calculated for the cooper(II) complexes by the atom-atom potential technique. The calculated values are compared to experimental sublimation enthalpies Δ H _T ⁰ .     

Ligating properties of model bioheterocyclics—I: Complexes of copper(II) and cobalt(II) halides with 3,6-disubstituted-2,7-dihydro-1,4,5-thiadiazepine derivatives

Copper(II) and cobalt(II) halides react with 3,6-disubstituted-2,7-dihydro-1,4,5-thiadiazepine derivatives(L) to form highly hygroscopic complexes of the general formulae, [(CuCl₂)₂L]₂nH₂O; [(CuBr₂)₃L₂]nH₂O and [CoX₂L]₂nH₂O respectively. On the basis of analytical, reflectance, paramagnetic susceptibility and molar conductance measurements, Cu(II) chloride and bromide complexes have been assigned dimeric and monomeric structures in which bridging through halogens and thiadiazepine ring takes place. These complexes are mixtures of stereoisomeric forms of square planar and distorted tetrahedral geometries. Co(II) complexes have been shown to possess tetrahedral geometry with dimeric structure in which bridging through only thiadiazepine ring occurs. Thermal stabilities, IR and PMR data is also reported. Here L acts as a bridging bidentate ligand by coordinating through two adjacently placed nitrogen atoms.     

Complexes of tris(o-phenanthroline)nickel(II) and copper(II) bromide with dithiocarbamates derived from α-amino acids

Complexes of 1,10-o-phenanthroline (o-phen)-Ni^II and Cu^II with dithiocarbamates derived from -amino acids (glycine, phenylalanine, alanine, methionine and tryptophan) were synthesized and characterized by chemical analysis, spectral and thermal studies and by biological screening; the complexes are non-electrolytes. The empirical formula are [Ni(o-phen)₂(aadtc)] and [Cu₂(o-phen)₂(phaladtc)(H₂O)₂Br₂] where, aadtc = glycinyl-, phenylalaninyl-, alaninyl-, methioninyl- and tryptophanyldithiocarbamate and phaladtc = phenylalaninyldithiocarbamate. The structure of these complexes is probably octahedral. Molecular association through hydrogen bonding between the —NH and the carboxylate groups is proposed for the Ni^II complexes. The Cu^II complex is dimeric with the phenylalaninyldithiocarbamate acting as a bridge.     

Synthesis and liquid-crystalline properties of substituted β-aminovinyl ketones and their complexes with copper(ii)

Mesogenic complexes were synthesized by the reaction of -aminovinyl ketones with copper(ii) acetate. On going from the ligands to complexes, the temperature of phase transitions increases and the nematic phase disappears. The initial members of the homological 1-(4-nonyloxyphenyl)-3-(4-methoxyphenylamino)-1-propen-1-one series demonstrate the alternation of clearing temperatures, which is absent for the corresponding copper(ii) complexes.     

Synthesis, structure, and antimicrobial activity of copper(II) chelates containing imidazole and condensation products of α-amino acids with salicylaldehyde and its derivatives

Salicylaldehyde, 5-bromo- and 5-nitrosalicylaldehydes, 2-hydroxynaphthalene-1-carbaldehyde, and 2,3-, 2,4-, and 2,5-dihydroxybenzaldehydes reacted with glycine, alanine, and phenylalanine in ethanol in the presence of imidazole (Im) and copper(II) acetate hydrate to give copper(II) chelates with the composition Cu(Im)(L) · nH₂O (H₂L is the condensation product of the above aldehydes with α-amino acids; n = 0–2). The structure of the complex Cu(Im)(L¹) [H₂L¹ = 2-(2-hydroxybenzylideneamino)acetic acid] was determined by X-ray analysis. The crystalline structure of [2-(2-hydroxybenzylideneamino)acetato](imidazole)copper is formed by polymeric chains of the Cu(Im)(L¹) molecules linked through bridging oxygen atoms in the carboxy groups of the Schiff base ligand. The coordination unit has a distorted tetragonal pyramid configuration, where the pyramid base is composed of the phenol and carboxy oxygen atoms, CH=N nitrogen atom in the ligand H₂L¹ and imidazole nitrogen atom. The oxygen atom in the carboxy group in the neighboring molecule occupies the apical position of the coordination pyramid. The other coordination compounds also have polynuclear structure with the Schiff base H₂L acting as doubly deprotonated tridentate O,N,O-ligand and bridging carboxy groups. Thermal decomposition of the complexes includes their dehydration (70–95°C), while complete thermal decomposition occurs at 360–530°C. The synthesized complexes showed selective antimicrobial activity in the concentration range from 75 to 300 μg/ml against a number of standard strains of Staphylococcus aureus and Escherichia coli.     

Synthesis and characterization of β-diketonato- and phenoxoderivatives of mono(dizirconium-ennea-isopropoxy)copper(II)

Summary -Diketonato- and phenoxo-derivatives of mono(dizirconium-ennea-isopropoxy) copper(II), [Cu{Zr₂(OPr-i)₉}-(RCOCHCOR)] and [Cu{Zr₂(OPr-i)₉}(-OAr)], have been prepared by the interaction of K(RCOCHCOR) or KOAr (1 mol) [R = R = Me (1a); R = R = CF₃ (1b); R = Me, R = CF₃ (1c); OAr = 2,6-Me₂C₆H₃O (2a), 3,5-Me₂C₆H₃O (2b), p-ClC₆H₄O (2c)] with [Cu{Zr₂-(OPr-i) ₉}(-Cl)] (1 mol) in PhH. Alcohol interchanges of the derivative [Cu{Zr₂(OPr-i)₉}(-Cl)] have also been studied. These new compounds have been characterized by elemental analyses, i.r., electronic and e.s.r. spectra, and magnetic susceptibility measurements. The studies indicate a distorted octahedral geometry around Cu^II.     

The structure and EPR spectra of binuclear copper(II) complexes with acyldihydrazones of β-diketones

The synthesis and structure of binuclear copper(II) complexes with acyldihydrazones of some β-diketones are described. The molecular structure of the copper(II) complex [Cu₂L·4Py] with trifluoroacetylacetone succinyldihydrazone (H₄L) was determined by the single-crystal X-ray analysis. Central atoms are bridged by a chain of seven σ-bonds with a Cu...Cu distance of 8.750 Å. EPR spectra of copper(II) complexes with acyldihydrazones of trifluoroacetylacetone and lower dicarboxylic acids containing from one to four methylene groups in the aliphatic spacer show the seven-line HFS due to spin-spin coupling of unpaired electrons with the two equivalent copper nuclei (g = 2.110, a = (38.5–40.5)⊙10^?4 cm^?1). By extending polymethylene spacer, as well as by modifying starting β-diketone, an exchange interaction between paramagnetic centers is suppressed.