Local Raman tensors in adenosine triphosphoric acid

A polarized laser (488.0 nm) Raman spectroscopic measurement has been made on a single crystal of a disodium salt of adenosine triphosphoric acid (Na₂ATP·3H₂O) by the use of a Raman microscope. The crystal belongs to an orthorhombic system of the space group P2₁2₁2₁, and has dimensions of 10, 100 and 100 μm along the crystallographic axes a, b and c, respectively. For each Raman band in the 300–1800 cm⁻¹ range, the scattering intensity ratio I _bb/I _cc of the bb and cc polarization components has been determined. For a few bands, the relative intensities of the bc components were also estimated. To augment the data, the depolarization ratio of each Raman band of ATP has also been determined for its acidic (pH = 2.42) H₂O and D₂O solutions. From these experimental results, the shapes and orientations of the Raman scattering tensors which are considered to be localized in the adenine-H⁺ portion and in the phosphate portion of the molecule have been derived.     

Kinetic regularities and reaction products of adenosine triphosphoric acid with the thiosulfate-nitrosyl iron complex

The kinetic characteristics of the reaction of adenosine triphosphoric acid (ATP) with the thiosulfate-nitrosyl iron complex (TNCI, donor of nitrogen monoxide) were obtained by the spectrofluorimetric method. The shape of the kinetic curves indicate a complicated mechanism of interaction between ATP and TNCI. The kinetic model for this process was proposed that satisfactorily describes the experimental data. The compositions and structures of the reaction products were determined. Iron in the reaction products is presented by two forms: Fe^II and Fe^III. The structures for the [ATP-Fe²⁺S] and [ATP-Fe³⁺S] complexes were proposed.     

A spectroscopic study of the reaction of the iron thiosulfate-nitrosyl complex with adenosine triphosphoric acid

The reaction of the nitric oxide donor, viz., iron tetranitrosyl complex bearing the thiosulfate ligand (TNIC), with adenosine triphosphoric acid (ATP) was studied. By spectrofluorometry and electronic microscopy, the formation of the reaction products of ATP both with TNIC and with Na₂S₂O₃ and FeSO₄ was shown and the complexation constants of ATP with these compounds were calculated.     

Complex formation equilibria of some aromatic beta-amino-alcohols

Complex formation equilibria of some aromatic beta-amino-alcohols with zinc(II), cadmium(II) and silver(I) have been investigated. The structure of the considered ligands (2-amino-1-phenyl-1-propanol, 2-amino-3-phenyl-1-propanol and 2-amino-1,3-propanediol) are similar to some hormones and alcaloids, like adrenaline, noradrenaline and ephedrine, and differ each other for the number and the relative position of alcoholic and phenyl groups. Equilibria constants at 25 degrees C and micro = 0.5 M (KNO3) have been determined by potentiometric titrations. The comparison of the obtained values with those previously determined for some aliphatic beta-amino-alcohols with the same polar heads has allowed to evidence the influence of aromatic ring on the coordinating properties of ligands, which is different depending on the considered metal ion. In particular, two contrasting effects have been evidenced. The electron withdrawing effect of the aromatic ring causes a decrease of amine basicity, more relevant when phenyl and hydroxylic groups are in 1-3 position, which reflects in a reduction of metal-NH2 coordination bond. This effect is predominant in the case of zinc(II) complexes and causes a reduction of complex stability which results directly proportional to the amine group basicity. On the other hand, in the case of silver(I) and cadmium(II) complexes, phenyl group seems to contribute directly to the coordination of the metal ion causing a stabilization of complexes.     

Complex formation of copper(II) with triethylenetetraminehexaacetic acid

The interaction between copper (II) and triethylenetetraminehexaacetic acid (TTHA) was investigated by polarographic, spectrophotometric and potentiometric methods. The existence of chelates with the formulae CuH-TTHA, Cu-TTHA and Cu₂-TTHA was shown. The polarographic behaviour and absorption curves of the chelates are described and the equilibrium constants defining the formation of the various species, are reported.     

Complex formation of trivalent americium with salicylic acid at very low concentrations

For the first time, the complexation of americium(III) with salicylic acid was studied at trace metal concentrations using a 2.0 m Long Path Flow Cell for UV–vis spectroscopy. The detection limit of Am(III) in aqueous solution at pH 3.0 was found to be 5 × 10⁻⁹ M. Two Am(III)-salicylate complexes were formed at pH 5.0 in 0.1 M NaClO₄, indicated by a clear red shift of the absorption maximum. The absorption spectra obtained from spectrophotometric titration were analyzed by means of factor analysis and complex stabilities were calculated to be log β₁₁₀ = 2.56 ± 0.08 and log β₁₂₀ = 3.93 ± 0.19.     

Interpolymer complex formation of some nonionogenic polymers with linear and crosslinked polyacrylic acid

The formation of interpolymer complexes on the surface of crosslinked poly (acrylic acid) with some nonionogenic polymers is compared with the complex formation in analogous linear polymer systems. The behavior of these systems is compared with that of complexes of two oppositely charged polyelectrolytes. The concentration redistribution of the linear polymer in the system polyelectrolyte network-polymer solution and the degree of swelling of this network in these solutions were determined. © 1994 John Wiley & Sons, Inc.     

Complex formation thermodynamics of some metal(II) phenyl-2-pyridylketoximates

The formation of phenyl-2-pyridylketoximates of nickel(II), zinc(II), cadmium-(II), mercury(II) and lead(II) was studied potentiometrically in a medium of 40% (w/w) acetone and 60% (w/w) water. The values of step formation constants, free energy, entropy and enthalpy of complex formation were calculated. The formation of the mercury chelate was found to be entropy driven. The formation of phenyl-2-pyridylketoximates of other metals of the first transitional series could not be studied owing to experimental difficulties.     

Voltammetric analysis of some carbamate pesticides

The electrochemical activity of 13 carbamate pesticides has been investigated in the potential range of a glassy carbon electrode, over a pH range from 2.5 and 10. Four compounds, pirimicarb, methiocarb, aminocarb and zectran, give oxidation waves; however, only those for aminocarb and zectran are suitable for analytical electrochemical detection in association with high-pressure liquid chromatography. The oxidation reaction has an ECE mechanism, proposed to involve formation of a carbamate cation radical. This hydrolyses to form a phenol which is in turn oxidized, the end product being a substituted dimethylamino-benzoquinoneimine.     

Complex formation reactions of two sterically hindered platinum(II) complexes with some N-bonding ligands

The kinetics of the complex formation reactions of two [(TL ^tBu)PtCl]⁺ and [Pt(tpdm)Cl]⁺ complexes (TL ^tBu = 2,6-bis[(1,3-di-tert-butylimidazolin-2-imino)methyl]pyridine and tpdm = terpyridinedimethane) with N-donor ligands, l-histidine (L-His), inosine (Ino), inosine-5′-monophosphate (5′-IMP) and guanosine-5′-monophosphate (5′-GMP), were studied. All reactions were studied under pseudo-first-order conditions as a function of nucleophile concentration and temperature in aqueous 0.1 M NaClO₄ solution in the presence of 10 mM NaCl using variable-temperature Uv–Vis spectrophotometry. The order of reactivity of the studied ligands is L-His > Ino > 5′-GMP > 5′-IMP. This order of reactivity is in relation to their electronic properties and structures. The mechanism of the substitution reactions is associative in nature as supported by the negative entropy of activation.     

Complex formation in concentrated sulfuric acid between boric acid and quinalizarin or alizarin

The complex formation in concentrated sulfuric acid between boric acid and quinalizarin (1,2,5,8-tetrahydroxyanthraquinone) or alizarin (1,2-dihydroxyanthraquinone) was studied by spectrophotometry. Both systems contained only one species, viz. a complex between one boric acid and one hydroxyanthraquinone molecules. The reactions of boric acid with hydroxyanthraquinones are discussed and compared with the reaction of boric acid with 1,1'-dianthrimide.     

Complex formation between poly(methylmethacrylate) and some transition metal ions

Differential scanning calorimetric and infrared spectroscopic studies revealed that poly(methylmethacrylate) interacts with Fe³⁺, Ni²⁺ and Cr³⁺ both in solution and in suspension. The tendency for these metal ions to complex with the polymer follows the sequence Fe³⁺2+3+. These observations are explained in terms of the radii of the ions and steric factors.

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Zusammenfassung DSC- und IR-Untersuchungen zeigen, daß Polymethylmethacrylat mit Fe³⁺-, Ni²⁺- und Cr³⁺-Ionen sowohl in Lösungen als auch in Suspensionen Wechselwirkungen eingeht. Die Tendenz dieser Metallionen, mit dem Polymer einen Komplex zu bilden steigt in der Reihenfolge Fe³⁺2+3+. Die Beobachtungen wurden anhand der Ionenradien und sterischer Faktoren erklärt.

     

Effect of iron and humic acid on photodegradation of some pesticides adsorbed on clay surfaces

Photochemistry studies can be helpful in assessing the environmental fate of chemicals. For this reason, the photodegradation kinetic studies of the two pesticides orthophenylphenol (OPP) and monuron, largely used in agriculture, were carried out in solid phase. The fungicide OPP and the herbicide monuron were irradiated on the clay fractions (montmorillonite and modified clays) using a suntest simulator. The phototransformation of the parent compound was followed by HPLC technique. The photodegradation process appears to follow the first order reaction. Kinetic parameters were determined and the experimental results show that the photodegradation of these substrates was enhanced in presence of K-montmorillonite, in comparison with Fe(III) exchanged montmorillonite and montmorillonite complexed with humic acid complexes. This study has shown that the iron and humic acid adsorbed on clay surfaces did not increase the degradation rate.     

Complex formation of 5-hydroxyorotic acid with copper(II) ions in water solutions

Complex formation of 5-hydroxyorotic acid with copper(II) chloride in water solution is studied by electron spectroscopy. The composition of the complex was established spectrophotometrically by molar ratio method and confirmed by elemental analysis. The constant of complex formation was calculated. By the IR spectroscopy the electron-donating centers of 5-hydroxyorotic acid taking part in coordination with metal ion were established. The structure of the obtained complex was suggested.     

Determination of carbamate pesticides and some urea pesticides after derivatization with acetic anhydride by means of GC-MSD

Summary A simple method for the determination of several thermolabile carbamate and urea pesticides as acetyl derivatives by means of capillary gas chromatography is described. 10 carbamate and 6 urea pesticides yielded thermostable derivatives which can easily be analysed by GC-MSD at the relevant residue levels as demonstrated with food samples. The method was designed to be used in addition to a popular multimethod (S19 — DFG Pesticide Commission).Part of this paper was presented at the Seventh International Congress of Pesticide Chemistry, Hamburg, August 5–10, 1990     

Character of the reaction of di- and polynucleotides with some pesticides

Lontrel, Sencor, Roundup, Kusagard, Tachigaren, Tilt, and Sethoxydim, as well as the bidentate Cu, Co, Ni, Mo, and Fe complexes of the herbicide Lontrel form molecular complexes with adenine heterocyclic compounds containing di- and polynucleotides. Sencor forms the strongest complexes, and Tilt has the lowest complexing constant. Lontrel, Sencor, Basagran, and Roundup totally destroy the cooperative character of the double helix of native DNA. The overall effect of the pesticides on nucleotides is determined both by the complexing constant with the purine base and by the capacity of the molecule of the pesticide to reach the reaction side located in the depth of the twisted double helix of DNA and RNA.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1984–1989, September, 1989.     

11B NMR study of p-carboxybenzeneboronic acid ions for complex formation with some monosaccharides.

The 11B NMR spectra of p-carboxybenzeneboronic acid (PCBA) ions demonstrated that their chemical shifts depend on the pH. At a lower pH, PCBA exists as a mixture of neutral PCBA and the monoanion with a trigonal structure, and at higher pH as the dianion with a tetrahedral structure. In the intermediate pH region, both the mono- and dianion coexist. The pKa of the monoanion of PCBA has been estimated to be 8.53. The complex formation constants of PCBA with several monosaccharides suggest that PCBA-fructose complex is most predominant.     

Complex formation and Fluorescence : Complexes of 8-hydroxyquinoline-5-sulfonic acid

The fluorescence of solutions of cation complexes with 8-hydroxyquinoline-5-sulfonic acid has been studied. The complexes formed with transition elements do not fluoresce. The additivity of the fluorescence at certain pH values has been used to indicate new generally applicable analytical method for mixtures of cations which have similar reactions. The method is especially applicable to small or very dilute samples.     

Complex formation of uranium(VI) with 4-hydroxy-3-methoxybenzoic acid and related compounds

Summary The complex formation of uranium(VI) with 4-hydroxy-3-methoxybenzoic acid as well as with benzoic acid and 4-hydroxybenzoic acid was studied. In aqueous solution weak carboxylic 1 : 1 complexes, are formed in which the carboxyl group is bidentately coordinated to the metal atom. The logarithmic stability constants of these complexes regarding the reaction of the uranyl ion with the single charged anion of the respective ligands are 2.78±0.02, 2.68±0.04, and 2.71±0.04 at an ionic strength of 0.1 mol/l (NaClO₄) and at 25 °C. Bis(4-hydroxy-3-methoxybenzoato)dioxouranium(VI) was obtained as a crystalline compound if the concentrations of the starting components for the synthesis are increased. The monoclinic compound has a reflections-rich X-ray powder diffraction pattern. The lattice constants are a = 13.662(9) ?, b = 21.293(7) ?, c = 11.213(3) ?, b = 107.49(4), and V = 3111(2) ?.³