Heteroligand Complexes Research Articles

Studies on Ni(II), Cu(II) and Zn(II) complexes with 2-aminobenzamide and some bioactive imidazole enzyme constituents

A series of Ni(II), Cu(II), and Zn(II) complexes of 2-aminobenzamide(2AB : L) and some imidazole enzyme constituents(B) viz., imidazole(him), benzimidazole(bim), histamine(hist), and L-histidine(his) have been synthesized and characterized using analytical and various spectral studies. Vibrational spectral data of the synthesized complexes reveal that the ligands bind with metal(II) ions through nitrogen and oxygen. The calculated g-tensor values of Cu(II) complexes suggest that the unpaired electron is localized in the orbital. The results obtained from the spectral studies confirm the distorted octahedral environment around the metal(II) ions. Their powder XRD indicates microcrystalline nature and SEM pictographs identify their uniform surface morphology. Cu(II) and Ni(II) complexes show biological, antioxidant, and DNA activities when compared to free 2-aminobenzamide. Equilibrium studies have been carried out pH-metrically in 50% (v/v) water–ethanol mixture at 37 °C and I = 0.15 mol dm−3 NaClO4. Analysis reveals the presence of certain heteroligand species viz., MLBH/MLB/MLB2, in addition to various primary species. In MLB/MLB2 species, 2AB(L) binds with M(II) ions via N-amino and O-amido, whereas the ligands(B) him and bim are monodentate, hist and his are bi and tridentate, respectively. The stabilization parameters Δ log K, log X, log X′, and % RS clearly indicate all the heteroligand complexes have higher stabilities than their primary.

Synthesis of lanthanide complexes of phthalocyanines containing both naphthoxy and benzotriazole fragments

Interaction of 4-(1-benzotriazolyl)-5-(2-naphthoxy)phthalonitrile with erbium or ytterbium chloride has afforded the lanthanide complexes of tetra-4-(1-benzotriazolyl)tetra-5-(2-naphthoxy)phthalocyanine. Fusion of erbium tetra-4-(1-benzotriazolyl)tetra-5-(2-naphthoxy)phthalocyaninate with phthalonitrile has yielded the corresponding sandwich-type heteroligand complex. The prepared compounds have been characterized by data of elemental analysis as well as IR and electronic spectroscopy; their thermal stability has been studied.

Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea

Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV–vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV–visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu–Crn–urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations.

Oxovanadium(iv) cations in heterometallic and heteroligand complex formation

The formation of heterometallic oxovanadium(iv) diethylenetriaminepentaacetates with titanium(iii), chromium(iii), cobalt(ii), nickel(ii), and manganese(ii) cations in aqueous solutions was studied by spectrophotometry and pH-metry. The stabilizing influence of heterometallic chelation on an unstable oxidation state of Ti iii and the labilizing effect of oxovanadium(iv) cations on the coordination of Cr iii cations by the carboxylate ligand anions in the heterometallic complex were shown. The optimum conditions for the formation of the heterometallic dtpa complexes were selected and their thermodynamic stability was estimated. The states of the oxovanadium(iv) cations in the monoand heteroligand systems involving polyamine, polyaminopolycarboxylate, and alkylpolyphosphonate ligands were studied. Specific features of ligand coordination and formation of the mixed-ligand chelates were investigated. A variety of molecular compositions of complex oxovanadium(iv) oxyethylenediphosphonate particles formed in ranges of pH 2.2—3.0, 4.5—5.5, and 6.3—6.4 was found. The preferability of formation of polynuclear oxovanadium(iv) oxyethylidenediphosphonates, viz., binuclear particles with oxovanadium(iv) cation to ligand molar ratios of 2 : 1 and 2 : 5 and trinuclear particles with a molar ratio of components of 3 : 2, was shown.

Stability and Solution Structure of Binary and Ternary Cu(II) Complexes with l-Glutamic Acid and Diamines as Well as Adducts in Metal-Free Systems in Aqueous Solution.

Binary and ternary complexes of copper(II) with l-glutamic acid (Glu) and diamines 1,3-diaminopropane and 1,4-diaminobutane, putrescine (tn, Put), as well as adducts formed in the metal-free systems, have been investigated in aqueous solutions. The types of complexes formed and their overall stability constants were established on the basis of computer analysis of potentiometric results. The reaction centers and the modes of interaction were identified on the basis of spectroscopic studies (NMR, Vis and EPR). In the ligands studied the interaction centers are the oxygen atoms from carboxyl groups, nitrogen atom from the amine group of glutamic acid and the nitrogen atoms from amine groups of the diamines. The centers of noncovalent interaction in the adducts that formed in the metal-free systems are also potential sites of metal ion coordination, which is important in biological systems. In the Glu–diamine systems, molecular complexes of the (Glu)Hx(diamine) type are formed. In the (Glu)H2(tn) adduct, in contrast to the corresponding complex with Put, an inversion effect was observed in which the first deprotonated amine group of tn became a negative reaction center and interacted with the protonated amine groups from Glu. Depending on the pH, the amine groups from the diamine can be either a positive or a negative center of interaction. In the Cu(Glu)2 species the first molecule of Glu takes part in metallation through all functional groups, whereas the second molecule makes a “glycine-like” coordination with the Cu(II) ions that is only through two functional groups. According to the results, introduction of Cu(II) ions into metal-free systems (Glu–diamine) changes the character of interactions between the bioligands in the complexes that form in Cu(II)–Glu–diamine systems and no ML…L′ type complexes are formed. However, in the ternary systems only the heteroligand complexes Cu(Glu)(diamine) and Cu(Glu)(diamine)(OH) are observed.

Mixed-ligand complexes of copper(II) ions with L-glutamic acid in the systems with triamines and non-covalent interaction between bioligands in aqueous solution

Abstract The interactions between L-glutamic acid (Glu) and 1,7-diamino-4-azaheptan (3,3-tri) and 1,8-diamino-4-azaoktan (Spd) in metal-free systems and in the appropriate Cu(II) ions complexes were studied by potentiometric and spectral methods. The composition and overall stability constants of complexes forming in the systems studied were determined and the reactions centres were identified. In the complex formation conditions, the ligands have positive and negative reaction centres, which are also the potential sites of metal coordination. Below pH 7 in metal-free systems, the terminal amine groups from both triamines and the oxygen atoms from –C(5)OO- group as well as the amine group from Glu do not take part in the weak noncovalent interactions between the ligands, but at higher pH all available active centres of the ligands are involved in the interactions in the adducts formed and the inversion effect is observed. In the Cu(II)/Glu/triamine systems, in the species MLHL’, both 3,3-tri and Spd were found to coordinate Cu(II) ions in the same way, while only in the Cu(Glu)H(Spd) complex the oxygen atoms from –C(5)OO- group of the amino acid do not take part in metallation. In the species MLL’ and MLL’OH with 3,3-tri, the chromophore formed was of different type than that formed in the corresponding species with Spd. This is related to the fact that the nitrogen atom from the amine group of Glu is inactive in the coordination. Thus, not only the length of the polyamine carbon chain but also the length of the amino acid carbon chain influence the interactions between the bioligands. The introduction of metal ions to Glu-Spd metal-free system excludes the interaction between the bioligands, and the ligands centres that do not take part in the weak interactions in the adduct (Glu)H(Spd) are involved in the metallation, but the centres that took part in the weak interactions are not involved in the coordination in a heteroligand complex.

ChemInform Abstract: The Supramolecular Nanostructures as Effective Catalysts for the Oxidation of Hydrocarbons and Functional Models of Dioxygenases

AbstractReview: 22 refs.

Modeling of equilibriums of formation of polynuclear chelates of nickel(ii) with histidine

Electronic absorption spectroscopy has been applied to study of protolytic and complex formation equilibriums in binary and tertiary systems containing nickel(II) salt, ethylenediaminetetraacetic acid and 2-amino-3-(imidazol-2-yl)propionic acid (ionic strength 0.1 mol/L aqueous NaClO4, 20±2°C). Fitting of experimental spectral properties as function of pH and the components concentration requires dissociation constants of the ligands as well as stability constants of homoligand, heteroligand, and polynuclear complexes as parameters. These parameters have been estimated from the best fit model, and possible complexes structures have been suggested.

Protolytic dissociation mechanisms and comparative acid stabilities of palladium(II), zinc(II), copper(II), and nickel(II) complexes of alkylated dipyrrins

Complexes of Pd(II), Cu(II), Ni(II), and Zn(II) with alkylated dipyrrins (Hdpm) were synthesized and characterized by physicochemical and spectroscopic methods. Protolytic dissociation kinetics of these complexes in benzene in the presence of acetic and trichloroacetic acid was studied. A protonated dipyrrin is the reaction product of protolytic dissociation of the complexes in acid solutions. The observed and true dissociation rate constants, as well as activation reaction parameters, were calculated. Kinetic models of the processes are proposed, and the patterns of influence of the ligand nature on dissociation kinetics were determined. The Pd(II) complexes proved to be much more stable than other those of the other metals, according to the results of the kinetic studies. The lability of the complexes strongly depends on the length and position of the alkyl substituent of the ligand. The dissociation of the Ni(II) complex gives a heteroligand complex at low concentrations of acid, but the complex undergoes full protolytic dissociation at higher concentrations of acid. The dissociation of the complex of Cu(II) is an equilibrium process, involving formation of the protonated form of the ligand.

Heteroligand polynuclear nickel(II) complexonates in aqueous solutions of 2,2′-dipyridyl

Formation of nickel(II) complexes with ethylenediaminetetraacetic acid (Edta) and 2,2′-dipyridyl (Dipy) has been studied by electronic absorption spectroscopy. Mathematical modeling has demonstrated that the most probable mathematical models to describe the experimental dependences of absorption on the medium acidity and concentration of solution components relies on the dissociation constants of the ligands (Ki) and stability constants (β) of homoligand, heteroligand, and polynuclear complexes of general composition [NimDipynEdtar]2m − 4r (m = 1–4, n = 0–8, r = 0–1) as parameters. The reaction equilibrium constants and stability constants of the resulting complexes have been calculated. The structures of these complexes have been suggested.

Water-soluble heteroligand complexes of 2-methyl-4-oxo-4H-pyran-3-olatoneodymium(III) with amino acids

New water-soluble heteroligand complexes of 2-methyl-4-oxo-4H-pyran-3-olatoneodymium(III) with aliphatic amino acids (glycine, N-methylglycine, and alanine) have been prepared. Within the biological “transparency window” (700–900 nm) of their electronic absorption spectra, narrow bands of Nd3+ are found: 4F7/2 ← 4I9/2; 4F5/2 ← 4I9/2; 4F3/2 ← 4I9/2 (750, 810, and 880 nm). Such complexes can be used as markers for biological tissues visualization.

Coordination polymer [Sm(Biq)(iso-Bu2PS2)3] n : Synthesis, structure, and photoluminescence

A heteroligand complex [Sm(Biq)(iso-Bu2PS2)3] n (Biq = 6,6′-biquinoline) is synthesized. According to the X-ray diffraction data, the complex is one-dimensional coordination polymer. The crystal structure is built of chains consisting of fragments Sm(iso-Bu2PS2)3 and molecules of the bidentate-bridging ligand Biq. The coordination polyhedron N2S6 of the Sm atom is a distorted tetragonal antiprism. The complex exhibits red photoluminescence (λmax = 562, 598, 642, and 703 nm).

Determination of Manganese in Tap Water by a New Extractionphotometric Method

The heteroligand complex of manganese with 1,10-phenantroline and o-nitrobenzolazosalicylic acid have been investigated by spectrophotometric method. The condition of complexing and extraction, physical-chemical and analytical characteristics of this complex have been found. Complex formation is observed in the pH range 5-11. Extraction constant was found as 5.3 × 1012, stability constant was found as lgβK=9.03 ± 0.03. Molar absorptivity is e=(1.36 ± 0.08) × 104. Beer's law is obeyed in the range of 1.0-22.5 mkq manganese(II). The extraction-photometric methods of manganese determination have been worked out. The influence of diverse ions on determination of manganese(II) has been studied. The proposed method was applied successfully to determine amount of manganese in tap water.

Determination of Manganese in Tap Water by a New Extraction-Photometric Method

The heteroligand complex of manganese with 1,10-phenantroline and o-nitrobenzolazosalicylic acid has been investigated by spectrophotometric method. The condition of complexing and extraction, physical-chemical and analytical characteristics of this complex have been found. Complex formation is observed in the pH range 5 - 11. Extraction constant was found as 5.3 × 1012, stability constant was found as lgβK = 9.03 ± 0.03. Molar absorptivity is ε = (1.36 ± 0.08) × 104 l·g﹣1·cm﹣1. Beer's law is obeyed in the range of 1.0 - 22.5 μkg manganese (II). The extraction-photometric methods of manganese determination have been worked out. The influence of diverse ions on determination of manganese (II) has been studied. The proposed method was applied successfully to determine amount of manganese in tap water.

Heteroligand complexes of lanthanides with 4-formyl-3-methyl-1-phenylpyrazol-5-one and 1,10-phenanthroline

Complexes of the general formula LnL3 · Phen (Ln = Nd, Sm, Eu, Gd, Tb, Dy, and Yb; HL = 4-formyl-3-methyl-1-phenylpyrazol-5-one, Phen = 1,10-phenanthroline) were obtained and examined by IR spectroscopy and thermogravimetry. The structure of the complex TbL3 · Phen was studied by X-ray diffraction. The coordination polyhedron of terbium is a distorted square antiprism made up of six O atoms of three 4-formylpyrazol-5-one anions and two N atoms of the 1,10-phenanthroline molecule. Polycrystalline samples of the complexes studied show emission in the spectral ranges characteristic of Ln(III).

Heteroligand copper(II) complexes with hydroxyethyleneiminodiacetic acid and bidentate nitrogen-containing ligands: Structures and properties

Procedures were proposed for the synthesis of the heteroligand copper(II) complexes with N-(2-hydroxyethyl)iminodiacetic acid (H2Heida) and 2-aminoethanol and ethylenediamine ligands. The optimal parameters of solutions for the isolation of ternary complexes were found. Heteroligand complexes Cu(Heida)En · 3H2O (I) and Cu(Heida)Mea (II) (En is ethylenediamine, and Mea is 2-aminoethanol) were examined by X-ray diffraction analysis. The thermal properties of complexes I and II and their thermodynamic stability in aqueous solutions were studied.

Synthesis and photoluminescence of complexes Tm(L)(iso-Bu2PS2)2(NO3) (L = Phen, 2,2′-Bipy). Crystal structures of compounds [Ln(2,2′-Bipy)(iso-Bu2PS2)2(NO3)] · C6H6 (Ln = Tm, Tb)

Heteroligand complexes Tm(L)(iso-Bu2PS2)2(NO3) (L = 2,2′-Bipy (II), Phen (III)) are synthesized. According to the X-ray phase analysis data, complex III is isostructural to mononuclear compound [Dy(Phen)(iso-Bu2PS2)2(NO3)] including, according to the X-ray diffraction data, a coordination polyhedron DyN2O2S4 (distorted dodecahedron). Single crystals of compounds [Ln(2,2′-Bipy)(iso-Bu2PS2)2(NO3)] · C6H6 (Ln = Tm (IV), Tb (V)) are obtained. An X-ray diffraction analysis shows that the crystal structures of these isostructural compounds are formed by molecules of mononuclear complexes [Ln(2,2′-Bipy)(iso-Bu2PS2)2(NO3) and uncoordinated C6H6 molecules. In complexes IV and V, the ligands [Ln(2,2′-Bipy)(iso-Bu2PS 2 − , and NO 3 − are bidentate-cyclic. The coordination polyhedron LnN2O2S4 is a distorted dodecahedron. Complexes II and III possess photoluminescence in the visible spectral range (λmax = 478 and 477 nm, respectively).

ChemInform Abstract: Lanthanide Acylpyrazolonates: Synthesis, Properties and Structural Features

AbstractReview: 75 refs.

Catalytic hydroformylation in the presence of rhodium complexes with homo- and heterocombination of two monodentate P-ligands

Activity of the complex containing both a phosphine and an amidophosphite ligand in the coordination sphere of rhodium was determined for the first time in the hydroformylation of styrene and oct-1-ene in supercritical carbon dioxide and benzene. The efficiency of this “mixed” heteroligand complex was compared with that of its analogs each containing the same two phosphine or two amidophosphite ligands.

Proton-lattice coupling and vibronic effects in KDP-family thermodynamics

Based on the vibronic theory of heteroligand complexes a new model Hamiltonian is proposed for the ferroelectrics of KDP (KH2PO4) family. In local representation three items of this Hamiltonian describe the H-bond protons, the potential energy of lattice's oscillators and the coupling of these two subsystems respectively. In Ising form, convenient for numerical calculations, the Hamiltonian offered includes explicitly the characteristics of the electronic structure as well as the orbital vibronic constants of the AO4 tetrahedra. The Ising version of theory is then applied to numerical studying of some questions for KDP thermodynamics.