The dissociation constants for N-(l-naphthyl)ethylenediamine (NEN) and the formation constants for binary (ML) and ternary
metal complexes (MLA), where M = Cu(II), L = alanine, phenylalanine, tryptophan, lysine, arginine, serine, threonine, aspartic
acid or histidine and A = NEN or ethylenediamine (EN) have been determined by pH titrations and are reported at 35°C (gm = 0.2 M KNO3). The relative stability of the ternary complexes are discussed in terms of statistical effects and the nature of ligands
in the coordination sphere of the metal ion. 相似文献
Employing a phenomenological mean field theory, we analyse the effect of high pressure on the B2I phase transition properties of a bent-core liquid crystal. The basic idea of the work is to explain the phase transition behaviour of system by assuming that certain Landau coefficients associated with the order parameters coupling terms of the free-energy density expansion are pressure dependent. We observe excellent agreement between the theoretical and experimental results of mesogen PHDBB and that the B2I transition remains first order even at the elevated pressures. 相似文献
General equations governing the stability of stratified fluid in a stratified porous medium in the presence of suspended particles and variable horizontal magnetic field, separately, have been derived. Assuming stratifications in density, viscosity, suspended particles number density, medium porosity, medium permeability and a magnetic field of exponential form the dispersion relations have been obtained. Systems have been found to be stable for stable stratifications and unstable for unstable stratifications. A system which was unstable in the absence of magnetic field can be completely stabilized by a magnetic field for a certain wave-number range. The behaviour of growth rates with respect to fluid viscosity, medium permeability, suspended particles number density and magnetic field has been examined analytically. 相似文献
Mixed-ligand complexes of Pt(II) and Pt(IV) with 2,6-diaminopurine and 6-thioguanine were synthesized and characterised. The complexes were prepared in acidic and basic media. The binding of the ligands to the metal ion varies according to the pH of the medium. Thus, in the complexes of 6-thioguanine, the ligand acts as a monodentate ligand coordinating through the neutral C6-SH group in the acidic medium and in the basic medium as a bidentate ligand binding to the metal ion through C6S? and N7, forming a five-membered chelate ring. In an acidic medium 2,6-diaminopurine forms mononuclear complexes with Pt(II) and Pt(IV) binding through N7. In a basic medium binuclear hydroxobridged complexes are formed with Pt(IV) and the ligand is monodentate, coordinating through N7. 相似文献
The kinetics of adsorption of chromate ions has been investigated radiometrically over a wide range of concentration of chromate ions (10–6–10–2M) and temperature (303–323 K). The kinetics of the process follows essentially a first order rate law with respect to adsorptive concentration and obeys the Freundlich adsorption isotherm in the concentration range studied. In addition, the kinetics of desorption of the preadsorbed species also follows a first order rate law and the activation energy for desorption is greater than that of the adsorption process. On the basis of an adsorption kinetic study, the thermodynamic parameters have been calculated. Infrared spectroscopy has shown the chemical interaction of chromate ions on the surface of MnO2. 相似文献
Benzene and maleic anhydride react over solid acids, viz. CrO3/Magnesol and SO42-/ZrO2 catalysts to form phthalic anhydride and olefins, which in turn produce phthalate esters as end products. Based on the product distribution, a reaction pathway is proposed. 相似文献
Heterocyclic chemistry has fascinated the researchers owing to its wide range of applications in various chemical fields. With this perspective, herein we present an environmentally benign procedure for the synthesis of pyrazole and its derivatives through multicomponent reaction by using SPVA as a heterogeneous acid catalyst. The synthesis protocol of SPVA catalyst includes functionalization of polyvinyl alcohol by sulfonic acid groups. The synthesized SPVA catalyst was then subjected to several characterization techniques to confirm its formation and study its physicochemical properties. The SPVA catalyst was then tested for its activity toward a multicomponent reaction of aromatic aldehyde, malononitrile and phenyl hydrazine. The SPVA catalyst with sufficient acidic sites displayed appreciable catalytic performance yielding 89% of the desired pyrazole product under ambient reaction conditions. The SPVA catalyst showed recyclability up to the sixth cycle without considerable loss in its activity. Furthermore, we made an effort to demonstrate the plausible mechanistic pathway for the SPVA-catalyzed pyrazole synthesis reaction. Interestingly, the present synthetic approach could effectively produce pyrazole products with high yields in the absence of base and solvent and in short reaction time making it a green and sustainable process.
Sorption of51Cr(VI) by MnO2 has been studied as a function of pH and ionic concentration in the presence of certain added cations and anions. The findings are explained in the light of deprotonation/hydroxyl ion association reaction on oxide surface and its subsequent interaction with the tracer. Infrared spectroscopy has shown the chemical interaction of Cr(VI) on the surface of MnO2. The influence of certain interfering ions has been shown on the sorption of51Cr(VI) on MnO2 surface. An attempt has been made to concentrate traces of51Cr under optimum experimental conditions. The experimental observation shows that the activity sorbed under specified conditions can be recovered appreciably by leaching the pre-adsorbed carrier. 相似文献
AbstractOne of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review. 相似文献