Structure and properties of anthranilato- andN-phenylanthranilatorhodium(I) complexes withcis,cis-cycloocta-1,5-diene

Summary Reaction products of [{RhCl(-COD)}₂] (COD=cycloocta-1,5-diene) with sodium salts of anthranilic andN-phenylanthranilic acid have been isolated and their structures and catalytic activities investigated. A monomeric square-planar structure with O-Rh-N bonds is postulated for the anthranilate complex, and a dimeric structure, with carboxylate bridges and without binding of the -amine nitrogen to rhodium, is postulated for theN-phenylanthranilate. Catalytic activities in hydrogenation of some alkenes, dienes, aromatic and heteroaromatic compounds have been investigated at ambient temperature and pressure. The stability of the complexes under hydrogenation conditions is low and complete saturation has been achieved only forn-alkenes and dienes.     

Counterion binding by surfactant/β-cyclodextrin inclusion complexes

Sodium ion activities were determined potentiometrically in sodium dodecylsulfate and sodium dodecanoate solutions containing-cyclodextrin. Whereas sodium ion did not bind with-cyclodextrin, its activity decreased noticeably when the 1:1-cyclodextrin/surfactant inclusion complex was formed in solution. When the anionic guest was methyl red or methyl orange, no sodium ion binding occurred. When the guest was the cationic dodecylammonium ion in chloride solutions containing-cyclodextrin, pronounced chloride ion binding to the 1:1 inclusion complex occurred.     

Solvent extraction of sodium picrate with 15-crown-5 into carbon tetrachloride. The determination of the dimer-formation constant of a crown ether-univalent metal salt 1∶1∶1 complex

The theory is derived to determine the dimer-formation constant,K ₂, of a crown ethermetal salt 111 complex in organic solvents of low dielectric constant by solvent extraction. The theoretical predictions are verified experimentally by extraction of sodium picrate (NaA) with 15-crown-5 (15C5) into carbon tetrachloride. All the experiments were conducted at 25°C. The logK ₂ value of the Na(15C5)A complex in carbon tetrachloride has been determined to be 4.05±0.11. Moreover, the partition constant of the complex is calculated.     

Complex Formation of Crown Ethers with Cations in the Water–Organic Solvent Mixtures. Part VII. Thermodynamic of Interactions of Na+ Ion with 15-Crown-5 Ether in the Mixture of Water with N,N-Dimethylacetamide at 298.15 K

The thermodynamic functions of the complex formation of 15-crown-5 ether with sodium cation in mixtures of water with N,N-dimethylacetamide at 298.15K are calculated. The equilibrium constants of complex formation of 15-crown-5 ether with sodium cation have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured by a calorimetric method at 298.15K. The complexes are enthalpy-stabilized but entropy-destabilized in this mixed solvent. A quantitative dependence of the excess molar enthalpy and entropy of complex formation on the structural and energetic properties of interactions between water and organic solvent molecules in the mixtures of water with N,N-dimethylacetamide, N,N-dimethylformamide and dimethylsulfoxide has been found. The linear entropy–enthalpy relationship for complex formation is also presented. The solvation enthalpy of the complex in the water–N,N-dimethylacetamide mixtures is discussed.     

Interaction of 5-fluorouracil with sodium poly-α,L-glutamate

The purpose of our research is to obtain an understanding of the binding mechanism and its correlations in terms of chemical structure and the potentiactive drug activity. The interaction of 5-fluorouracil (5-fluorouracil is used as an anticancer drug) with sodium poly-,L-glutamate in aqueous solution was studied with a spectral method and viscosity measurement. From the binding data, the molar change in enthalpy, entropy and the number of binding sites on the polymer were calculated. It is very interesting that the value ofH⁰ of the binding of 5-fluorouracil with sodium poly-,L-glutamate is smaller than that of 5-trifluoromethyluracil (although 5-trifluoromethyluracil is not used as an anticancer drug, the compound has a similar structure to 5-fluorouracil).     

Enantioseparation of Three β-Agonists Using Di-n-butyl d-Tartrate-Boric Acid Complex as Chiral Selector by Means of MEEKC

In this study, a self-prepared complex chiral selector, di-n-butyl d-tartrate-boric acid complex, by the reaction of di-n-butyl d-tartrate with boric acid in a running buffer was used as a chiral selector for the enantioseparation of three β-agonists including clenbuterol, cycloclenbuterol and tulobuterol by means of microemulsion electrokinetic chromatography (MEEKC). Three β-agonists were successfully enantioseparated using the chiral system, indicating that the di-n-butyl d-tartrate-boric acid complex was a useful chiral selector. The effects of di-n-butyl d-tartrate and sodium tetraborate concentration, surfactant concentration, cosurfactant, phosphate, buffer pH and composition, as well as applied voltage were extensively investigated to achieve a good enantioseparation. The di-n-butyl d-tartrate and sodium tetraborate concentration in the running buffer had great influence on the chiral resolution (R _s). Three β-agonists which could not be separated with only di-n-butyl d-tartrate, obtained good chiral separation using the complex chiral selector; among them, two pairs including clenbuterol and cycloclenbuterol could be baseline resolved in 7 min under optimized experimental conditions of 0.8% (w/v) di-n-butyl d-tartrate, 40 mM sodium tetraborate, 3.0% (w/v) Tween-20 and 60 mM sodium dihydrogen phosphate with 25 kV as running voltage. The results indicated that the method could be used for the enantioseparation of three β-agonists.

     

Hydrolysis of Chitin-Glucan Complex of Aspergillus niger Fungus with Phosphoric Acid

The kinetic parameters of hydrolysis of chitin-glucan complex of Aspergillus niger fungus with 85% phosphoric acid were studied at three temperatures. The activation energies of hydrolysis of chitin and glucan components of the complex were determined.     

Interaction of 1-(2-tetrahydrofuryl)-5-fluorouracil with sodium poly-α,L-glutamate

Summary The interaction of an anticancer drug, 1-(2-tetrahydrofuryl)-5-fluorouracil with sodium poly-,L-glutamate in aqueous solution was studied with a spectral method and viscosity measurement. From the binding data, the molar change in enthalpy, entropy and the number of binding sites on polymer were calculated. The standard affinity of 1-(2-tetrahydrofuryl)-5-fluorouracil is about –10 kcal/ol with sodium poly-,L-glutamate. The affinity is also very high.With 6 figures and 2 tables     

Two-Dimensional Supramolecular from the Self-Assembly of Dissymmetrical Oxamidato-Bridged Heterometallic Trinuclear Building Blocks: Synthesis, Crystal Structure, and Magnetic Properties

Two heterometallic trinuclear complexes {[Cu(oxbp)]₂Co(H₂O)₂}1.5DMF0.5H₂O (complex 1) and {[Cu(oxbm)]₂Co(H₂O)₂}2DMF (complex 2) were obtained from the self-organization of two new dissymmetrical oxamidato-bridged copper(II) building blocks [Cu(oxbp)]^– and [Cu(oxbm)]^–[H₃oxbp=N-benzoato-N'-(3-aminopropyl)oxamido, H₃oxbm=N-benzoato-N'-(2-amino-2-methylethyl)oxamido, DMF=dimethylformamide]. The crystal structure of complex 1 has been determined. Complex 1 crystallize in triclinic system, space group P-1, a=8.0609(16) Å, b=10.661(2) Å, c=22.279(5) Å, =85.32(3), =86.64(3), =70.90(3), and Z=1. The crystal structure of complex 1 consists of neutral trinuclear complex units, and hydrogen bond involved DMF and water molecules. Through the hydrogen bonds, weak coordination and CuCu weak interactions, complex 1 features a 2-D supramolecular structure. Magnetic susceptibility measurements (5–100 K) indicate that the central Co(II) and terminal copper metal ions are antiferromagnetically coupled with J=–28.09 and J=–29.70 cm^–1 for complex 1 and 2, respectively.     

Thermodynamics of surfactant-dye complex formation in aqueous solutions II. Sodium dodecyl sulfate and some azo oil dye systems

Spectrophotometric and thermodynamic investigations are reported of the interactions between anionic surfactant (sodium dodecyl sulfate) and six azo oil dyes (benzene azo naphthalene type) which have an amino group at 4-position of naphthalene. A pronounced spectral change in the dye solution occurs on addition of surfactant. For increasingly surfactant concentrations (below the CMC), the interaction between dye and surfactant is so sharp that the systems may be said to exhibit an isosbestic point; then a new absorption band appears at longer wavelengths. The spectral data can be quantitatively interpreted in terms of a complex formation. The equilibrium coefficients of the complex formation are determined at different temperatures. The thermodynamic parameters of the complex formations (the free energy change (G), enthalpy change (H) and change in entropy (S) are also calculated. The reaction of complex formation is exothermic (H negative).G is dependent on the hydrophobic nature andpKa of the dye. These complexes will form due to hydrophilic-hydrophilic interaction and will become more stable due to hydrophobic-hydrophobic interaction.With increasing amounts of complex, the infinite adsorption, the exhaustion and the rate constant of dyeing for nylon decrease.     

Influence of Sodium Dodecyl Sulfate on the Protolytic Properties of N,N-Dimethyl-N′-(2-hydroxybenzyl) Ethylenediamine and Its Complexation with Copper(II)

To investigate the effect of sodium dodecyl sulfate (concentration C _s = 5 and 10 mM) on the acid–base properties of N,N-dimethyl-N-(2-hydroxybenzyl) ethylenediamine and its complexation with copper(II) (C _s = 10 mM) was studied using the methods of potentiometry, spectrophotometry (at 298 K), and mathematical simulation of equilibria in solutions. The sodium dodecyl sulfate contributes to the formation of a monomeric form of N,N-dimethyl-N-(2-hydroxybenzyl)ethylenediamine, while this compound exists in 40% isopropyl alcohol predominantly in the form of a dimer. The acidic properties of protonated monomeric and dimeric species are weaker than those in an aqueous alcohol solution. Sodium dodecyl sulfate facilitates the coordination of the deprotonated form of ligand. The region of the predominant accumulation of an uncharged complex of 1 : 2 composition is shifted to lower pH values (11.0 and 7.5, respectively), whereas the molar absorption coefficient of the complex increases by approximately 1.7 times. The apparent stability constants of complexes of the same type increase.     

Synthesis,Characterization, and an ab initio Study of a Manganese(II) Macrocyclic Schiff-Base Complex with Two 2-Aminoethyl Pendant Arms

The cyclocondensation of 2,6-diformylpyridine with N,N,N,N-tetrakis(2-aminoethyl)ethane-1,2-diamine (pentene) in the presence of Mn^II forms the [1 + 1] pendant arm Schiff-base macrocyclic complex, [MnL³]²⁺. The ligand is a 15-membered pentaaza macrocycle having two 2-aminoethyl pendant arms {L³= 6,9-bis(aminoethyl)-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18),2,12,14,16-pentene}. The complex, investigated by analytical, spectroscopic and magnetic techniques, supports the formation of a highly symmetrical pentagonal bipyramid complex with the Mn^II ion located within a pentaaza macrocycle and two pendant amines coordinating on opposite sides of a plane defined by the macrocycle and the metal ion. The structure of the complex was also verified by ab initio HF-MO calculations using a standard 3-21G basis set.     

Stoichiometry and conformation of the azacrown moiety in sodium complexes of azacrown ethers. A Raman/IR spectroscopic study. Part I: Complexes of 4,13-Diaza-18-crown-6

Three sodium complexes (bromide, iodide and thiocyanate) of 4,13-diaza-18-crown-6 were studied using Raman and IR spectroscopy and normal coordinate calculations to probe the stoichiometry of the complexes and the variation in the conformation of azacrown moiety on complex formation. complex formation is accompanied by characteristic shifts of the bands, especially of those in the 800–900 cm^–1 region. Complexes of both 11 and 21 stoichiometry were observed. Normal coordinate calculations showed the reduction of symmetry of azacrown moiety toC _i , in contrast to theC _2h symmetry known for the parent azacrown and potassium thiocyanate complex.     

Volumetric and conductometric studies on the interactions of dipeptides with sodium acetate and sodium butyrate in aqueous solutions at T = 298.15 K

Densities and conductivity data for the sodium carboxylate (sodium acetate and sodium butyrate)–dipeptides {(glycyl-l-glutamine and l-alanyl-l-glutamine) + water} systems were determined at T = 298.15 K. The apparent molar volumes of the peptides and the molar conductivity (Λ) of sodium acetate and sodium butyrate have been calculated. These data have been utilized to deduce the standard partial molar volumes (), standard partial molar volumes of transfer for dipeptide from water to aqueous sodium carboxylate solutions (Δ_tV^°), volumetric interaction coefficient, the limiting molar conductivity (Λ_°), and Walden product (Λ_°η). Both and Δ_tV^° for the dipeptides increase with increasing concentration of sodium carboxylate. The interpretation is that this result arises from the dominant interactions of the sodium carboxylate with the charged group and polar groups of peptides. The decrease in Λ_° of sodium carboxylate with increasing dipeptide concentration and nonconstant Walden product are attributed to the interactions of sodium carboxylate with peptide and friction resistance of the solvent medium.     

Complex formation of some nonionic surfactants with hydroxypropyl-β-cyclodextrin and with heptakis (2,6-di-O-methyl)-β-cyclodextrin

The interaction of six nonionic surfactants -[4-(1,1,3,3-tetra-methylbutyl)phenyl]--hydroxypoly(oxy-1,2-ethanediyl) with hydroxypropyl--cyclodextrin (HPCD) and dimethyl--cyclodextrin (DIMEB) was studied by reversed-phase thin-layer chromatography in the presence and absence of sodium chloride. Each surfactant formed complexes with both cyclodextrin derivatives; however, the strength of interaction varied considerably. DIMEB formed more stable inclusion complexes with the surfactants than did HPCD. A longer ethyleneoxide chain decreased the strength of interaction, whereas sodium chloride exerted a negligible impact. Principal component analysis indicated that both the hydrophobicity and the specific hydrophobic surface are of the surfactant influenced the complex formation indicating the hydrophobic character of the interaction.Dedicated to Professor József Szejtli.     

Kinetics and mechanism of the oxidation of L-ascorbic acid by the N,N′-ethylenebis(salicylideneiminato)manganese(III) complex in aqueous solution

Summary The kinetics of oxidation of l-ascorbic acid by the N,N-ethylenebis(salicylideneiminato) manganese(III) complex have been studied over the 4.5–9.3 pH range. An intermediate ascorbate complex was formed which had an inhibiting effect on the rate of the redox reaction. The rapid formation of this intermediate was followed using the stopped-flow technique, whereas its slow decomposition was monitored using a conventional spectrophotometer. The formation of this intermediate was strongly pH dependent. Addition of sodium perchlorate and sodium dodecyl sulphate (anionic surfactant) affected the reaction rate. A probable mechanism comprising both the intermediate formation and the overall redox reaction is discussed.     

Rheological and electron microscopic characterization of aqueous carboxymethyl cellulose gels Part I: Rheological aging of aqueous gels of carboxymethyl cellulose in the free acid form (HCMC)

Aqueous gels of carboxymethylcellulose in the free acid form (HCMC) are obtained when dialyzed sodium carboxymethylcellulose (NaCMC)-gels are treated with a strongly acidic ion exchanger. These gels age rheologically. During the aging process (maximum 60 days), thixotropy and increased viscoelasticity occur. The rheological changes are measured by shear viscosity, coefficient of thixotropy H, complex dynamic shear modulus G^*, shear storage modulusG, shear loss modulusG, and tangent of the phase angle. The aging process is caused by the formation of quasi-crystalline microaggregates of HCMC which can be detected by electron microscopy (Part II).     

An improved LCAO interpolation scheme for energy band structures. Application to four compounds (ScN,ScP, TiN,ZrN) crystallizing in the sodium chloride structure

An improved version of the LCAO interpolation scheme using metal s-, p-, d-, and non metal s-, and p-basis functions is presented for transition metal compounds with sodium chloride structure. This method enables us to interpolate with reasonable accuracy occupied bands as well as unoccupied energy bands up to 0.9 Rydberg above the Fermi level for the compounds ScN, ScP, TiN and ZrN. Due to the limited basis, problems arise however with bands of predominantly transition metal f or non metal d character lying in this energy range - as is the case for ScP.Optimized parameter sets are presented for the compounds ScN, ScP, TiN and ZrN. They were used for the calculation of the imaginary part of the complex dielectric function, ₂(), as will be shown in two forthcoming papers.     

X-Ray Structural Analysis of NiII, PdII, and PtII Complexes with the Potentially Tridentate Ligand 1,3-Bis(diphenylphosphinomethyl)benzene, 1,3-C6H4(CH2PPh2)2

The ligand 1,3-bis(diphenylphosphinomethyl)benzene, 1,3-C₆H₄(CH₂PPh₂)₂ undergoes cyclometalation reactions, thus forming derivatives containing the tridentate moiety 2,6-bis(diphenylphosphinomethyl)phenyl,2,6-C₆H₃(CH₂PPh₂)₂. Complexes of the type trans-[MBr(C₆H₃CH₂PPh_{2 2})] with M = Ni^II, Pd^II, and Pt^II could be obtained and their crystal structures were here determined by X-ray diffraction (XRD) methods. The Ni complex belongs to the space group P2 ₁/c with a = 10.257(2), b = 16.234(5), c = 17.475(4) Å, = 109.34(2), and Z = 4. The Pd complex belongs to the space group P2 ₁/n with a = 10.325(3), b = 16.279(4), c = 17.303(4) Å = 105.34(3), and Z = 4. The Pt complex belongs to the space group P2 ₁/n with a = 10.127(2), b = 14.776(2), c = 19.023(3) Å, = 91.01(1), and Z = 4. Different distortions are induced by the rigid tridentate ligand on the square planar coordinations of the three metals. A significant difference between the two M-P bond distances is present in the Pt complex and can also be found in an analogous Pd complex.     

Spectroscopic effects of organized media on a cyanine dye/pyrene derivative

The absorption and fluorescence spectra of a cyanine dye/pyrene derivative are studied in the presence of-cyclodextrin, Brij 35, cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). Benesi-Hildebrand type equations are used to estimate the apparent association constant of the dye/cyclodextrin complex. In addition, an estimate of the dimerization constant for the dye is examined.