Search results for "Solution"
showing 10 items of 5638 documents
Kinetic and Mechanistic Aspects of a Poly(o-Toluidine)-Modified Gold Electrode. 2. Alternating Current Electrogravimetry Study in H2SO4 Solutions
2012
International audience; Electrodeposited poly(o-toluidine) (POT) on gold electrodes was investigated in 0.5 M H2SO4 aqueous solutions using alternating current electrogravimetry (simultaneous electrochemical impedance and mass transfer functions). The kinetic aspects of the three different redox transitions proposed for this polymer (leucoemeraldine-polaron transition, polaron-bipolaron transition, and bipolaron-pernigraniline transition) and the species involved, cation (hydrated proton), anion (bisulfate ion), and free solvent (water), are studied by means of the mass impedance technique. An ionic transfer model is proposed with coherent results where anion transfer is the fastest process…
Complex formation of copper( ), nickel( ) and zinc( ) with ethylophosphonoacetohydroxamic acid: solution speciation, synthesis and structural charac…
2019
We present herein the thermodynamic and X-ray characterisation of a novel ethyl phosphonohydroxamic acid-based Cu( ) metallacrown, predominating in solution in a broad pH range.
Complexation of the potassium ion by diaza crown compounds in aqueous solutions
1988
The conductance behavior of potassium nitrate in water with and without 1,7,10,16-tetraoxa-4,13-diazacyclooctandecane[2.2] and 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo-8.8.8-exacosane[2.2.2] macrocyclic ligands have been studied in order to analyze the complexation behavior of potassium cations in water. The absence of the complexation found in the [2.2] system is discussed in terms of the ligand structural features (presence of hydrogen bond donor and acceptor sites). The ion pair association constant of potassium cryptate as obtained from conductance measurements is also reported and discussed.
Lateral organization of G M1 in phase-separated monolayers visualized by scanning force microscopy
2002
Phase separation of glycolipids in lipid mono- and bilayers is of great interest for the understanding of membrane function. The distribution of the ganglioside GM1 in sphingomyelin (SM)/1-palmitoyl-2-oleoyl- sn-glycero-3-phosphocholine (POPC), SM/1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DOPC) and SM/cholesterol/POPC Langmuir-Blodgett (LB) monolayers transferred at 36 mN/m has been studied by scanning force microscopy. Besides lateral organization of the glycolipid in LB monolayers as deduced from topography, material properties have been investigated by phase imaging, pulsed force mode and force modulation microscopy. It was shown that GM1 preferentially clusters in an ordered lipid m…
Calculation of the pH and the titratable acidity in clinically used infusion solutions.
2006
Clinically used infusion solutions are complex aqueous mixtures composed of a variety of different salts, acids, and non-electrolytes, and are characterized by composition, initial pH, and titratable acidity (TA). By rigorous treatment as a multi-composed acid-base system, pH and TA were calculated from proton dissociation equilibria, mass balance equations and electroneutrality condition. Nine were arbitrarily chosen as model solutions in which pH and TA were experimentally determined. From composition, and based on a set of apparent acidity constants (pK values) at 37 degrees C and total ionic strength 0.155 mol/l, pH was calculated by iteration. In the model solutions, measured pH was in…
Mößbauer- und ESCA-Untersuchungen zur Bildung oxidischer Eisenphasen in wäßrigen Medien unter der Einwirkung organischer Korrosionsinhibitoren
1982
Korrosionsschichten auf Stahl nach Exposition in Wasser mit bestimmter Harte und Chloridgehalt wurden hinsichtlich der Wirksamkeit beigefugter organischer Inhibitoren mittels Mosbauer- und ESCA-Spektroskopie untersucht. Es entstehen relativ dicke Schichten mit einem unerwartet niedrigen Eisengehalt in Form von FeOOH. Die Schichten enthalten merkliche Mengen von Ionen aus der Testlosung und auch Abbauprodukte der Inhibitormolekule. Letztere werden anscheinend in dem korrosiven Medium zersetzt. Es ist anzunehmen, das das Gesamtmolekul zwar den Transport des Inhibitors zum Metall beeinflust, die eigentliche Inhibierung aber allein durch funktionelle Gruppen erfolgt. Mossbauer and ESCA investig…
A biocompatible ZnNa2-based metal–organic framework with high ibuprofen, nitric oxide and metal uptake capacity
2020
Metal organic frameworks (MOFs) have received significant attention in recent years in the areas of biomedical and environmental applications. Among them, mixed metal MOFs, although promising, are relatively few in number in comparison with their homometallic analogues. The employment of benzophenone-4,4′-dicarboxylic acid (bphdcH2) in mixed metal MOF chemistry provided access to a 3D MOF, [Na2Zn(bphdc)2(DMF)2]n (NUIG1). NUIG1 displays a new topology and is a rare example of a mixed metal MOF based on 1D rod secondary building units. UV-vis, HPLC, TGA, XRPD, solid state NMR and computational studies indicated that NUIG1 exhibits an exceptionally high Ibuprofen (Ibu) and nitric oxide adsorpt…
Synthesis and characterization of acetazolamide complexes of Ni(II), Cd(II), Hg(II), and Ag(I)
1989
The preparation and characterization of K2Ni2(Acm)3·5H2O, Cd(Acm)·32 H2O, Hg(Acm)·12H2O, Ag2(Acm), and Ag2(Acm)(NH3) complexes are described. The spectral properties suggest that Acm interacts with the metal ions through the doubly deprotonated form as observed in the [Cu(Acm)(NH3)2(OH2)]2·2H2O complex, whose crystalline structure has been previously reported. The crystal field parameters of the Ni(II) complex indicate an octahedral environment for the metal ion in the solid and its aqueous, DMSO, and DMF solutions. UV spectra of all the Acm complexes until now synthesized are discussed.
Electrochemical molecular recognition of silver cation by electropolymerised thieno[3′,4′:5,6][1,4]dithiino[2,3-b]quinoxaline: a joint experimental a…
2000
The novel annelated monomer thieno[3′,4′:5,6][1,4]dithiino[2,3-b]quinoxaline 1 has been electropolymerised on a variety of electrodes, resulting in films which are electroactive in non-aqueous and aqueous solution. The polymer films exhibit a transformation in voltammetric response corresponding to a positive shift in redox potential in the presence of silver cation, the maximum shift being ca. 150 mV in acetonitrile and ca. 400 mV in aqueous LiClO4 solution. Mercury dication demonstrates a similar, but smaller (ca. 130 mV) shift in aqueous solution. Theoretical calculations clearly show the potential of poly(1) as a metal complexation agent. The Ag+ ion coordinates with 1 in two ways: (i) …
Molecular simulation studies of water physisorption in zeolites
2006
We report a series of Grand Canonical Monte Carlo simulations of water adsorption in NaY and NaX faujasite, as well as in silicalite-1. Computed adsorption isotherms and heats of adsorption were in good agreement with the available experiments. The existence of cyclic water hexamers in NaX located in the 12-ring windows, recently disclosed by neutron diffraction experiments (Hunger et al., J. Phys. Chem. B, 2006, 110, 342-353) was reproduced in our simulations. Interestingly enough, such cyclic hexamer clusters were also observed in the case of NaY, in which no stabilizing cation is present in the 12-ring window. We also report cation redistribution upon water adsorption for sodium faujasit…