Standard ion transfer potential at the water|butyronitrile interface

Butyronitrile is an organic solvent stable enough to be used in photochemical reactions at liquid/liquid interfaces. However, it provides a rather short polarisation window making the analysis of ion transfer across the water|butyronitrile interface challenging. Here, steady-state cyclic voltammetry, at microhole-supported micro-interfaces, was used to measure Gibbs energies of transfer. A linear relationship between the standard Gibbs energies of ion partition for the water|butyronitrile interface and the water|1,2-dichloroethane and water|nitrobencene interfaces was found, making easy to extrapolate the Gibbs energy of other ions from this empiric correlation.Fil: Riva, Julieta Soledad. Swiss Federal Institute Of Technology Epfl; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Bassetto, V. C.. Swiss Federal Institute Of Technology Epfl; SuizaFil: Girault, Hubert. Swiss Federal Institute Of Technology Epfl; SuizaFil: Olaya, A. J.. Swiss Federal Institute Of Technology Epfl, Lausanne

FePd nanowires modified with cyclodextrin as improved catalysts: Effect of the alloy composition on colloidal stability and catalytic capacity

In the present work, FePd nanowires of different compositions, namely Fe85Pd15, Fe65Pd35, Fe55Pd45 and Fe0Pd100, were synthesized by electrodeposition into the nanopores of alumina membranes. The samples were characterized by XRD, SEM, EDS, XPS, and magnetometry. The surface of the nanowires was functionalized with a cyclodextrin derivative (βCDMOD14) to obtain stable aqueous dispersions. A comprehensive study on the relationship between the alloy composition and the catalytic capacity of FePd nanowires (FePdNWs) modified with βCDMOD14 was conducted through the analysis of the rate constants (kobs) of the reduction reaction of 4-nitrophenol to 4-aminophenol with sodium borohydride mediated by the FePdNWs in water. The highest value of kobs was observed for Fe55Pd45 NWs, but the catalytic performance of Fe65Pd35 NWs was similar to the previous one, in spite of its lower Pd content. The presence of Fe atoms and the synthesis method promotes the formation of an fcc phase in the alloy, which shows higher catalytic activity than pure Pd, possibly because of a synergistic effect exerted by Fe. The catalysts can be easily recovered by taking advantage of their magnetic properties, to be reused after reactivation with βCDMOD14.Fil: Herrera, Elisa Gabriela. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Instituto Nacional del Agua. Gerencia de Programas y Proyectos. Centro de la Region Semiarida.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Riva, Julieta Soledad. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aprea, María Soledad. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Silva, Oscar Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; ArgentinaFil: Bercoff, Paula Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Granados, Alejandro Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentin

A self-assembled organic/metal junction for water photo-oxidation

We report the in situ self-assembly of TTF, TTF ·+ , and BF 4 - or PF 6 - into p-type semiconductors on the surface of Pt microparticles dispersed in water/acetonitrile mixtures. The visible light photoactivation of these self-assemblies leads to water oxidation forming O 2 and H + , with an efficiency of 100% with respect to the initial concentration of TTF ·+ . TTF ·+ is then completely reduced to TTF upon photoreduction with water. The Pt microparticles act as floating microelectrodes whose Fermi level is imposed by the different redox species in solution; here predominantly TTF, TTF ·+ , and HTTF + , which furthermore showed no signs of decomposition in solution.Fil: Olaya, Astrid J.. Swiss Federal Institute Of Technology Epfl; SuizaFil: Omatsu, Terumasa. Kyoto Institute Of Technology; JapónFil: Hidalgo-Acosta, Jonnathan C.. Swiss Federal Institute Of Technology Epfl; SuizaFil: Riva, Julieta Soledad. Swiss Federal Institute Of Technology Epfl; Suiza. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bassetto, Victor Costa. Swiss Federal Institute Of Technology Epfl; SuizaFil: Gasilova, Natalia. Swiss Federal Institute Of Technology Epfl; SuizaFil: Girault, Hubert. Swiss Federal Institute Of Technology Epfl; Suiz

Very low potential electrodeposition of Sm-Co nanostructures in aqueous medium using hard templates

Arrays of SmCo nanowires (NW) and nanotubes (NT) with a diameter of 200 nm and different lengths are synthesized by electrodeposition into the nanopores of an alumina membrane. The potential applied during the synthesis largely determines the nanostructure morphology, its crystallinity and composition. Potentials investigated are between −0.8 V and −3.0 V; in the potential range between −0.8 V and 1.0 V, long and perfectly ordered nanowires are obtained with a composition close to that of the equilibrium Sm2Co17 phase in the binary alloy. For higher potentials, above −1 V, samples are nanotubes, 195 nm in external diameter and wall thickness of 30 nm with an equiatomical composition. Magnetic characterization reveals that all the nanostructures are soft ferromagnetic, with coercivity values below 60 mT. From the angular dependence of coercivity and the relative remanence it may concluded that in both, nanowires and nanotubes the magnetization reversal mechanism undergoes a transition from one at smaller angles, involving localized nucleation by curling, and further expansion of vortex-like domain walls. At higher angles, where the applied field is almost perpendicular to the NW/NT long axis, the mechanism changes to one involving nucleation by localized coherent rotation and further expansion of transverse Bloch-like walls.Fil: Herrera, Elisa Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Riva, Julieta Soledad. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pozo Lopez, Gabriela del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Condo, Adriana Mar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energia Atomica. Gerencia D/area Invest y Aplicaciones No Nucleares. Gerencia de Física (cab). Div.física Teórica; ArgentinaFil: Urreta, Silvia Elena. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Fabietti, Luis Maria Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin

The effect of the functionalization and molecular weight of cationic dextran polyelectrolytes on their electrochemical behavior at the water/1,2-dichloroethane interface

The electrochemical behaviour of several cationic dextran polyelectrolytes, aminodextran (AD), cationic dextran (CD) and diethylaminoethyl dextran (DEAE-D), at the polarized water/1,2-dichloroethane interface was studied. An investigation into the influence of the scan rate, concentration, pH, the nature and the concentration of the anion present in the organic electrolyte and the effect of the polymer molecular weight is presented. Different responses were obtained and explained considering the structural difference between these species, mainly the position of the positive charge in the macromolecule. The AD polymer is not transferred to the organic phase, regardless of molecular weight, while CD and DEAE-D are transferred from the aqueous to the organic phase at E = 0.650 V, independent of the polymer concentration and of the molecular weight. The shape of the voltammograms corresponding to DEAE-D transfer as well as the magnitude of the peak currents and the peak potential values were all dependent on the pH of the aqueous phase solution and on the nature and concentration of the anion present in the organic electrolyte. Based on this dependence, we postulated a mixed mechanism, which involves the transfer of dissolved and adsorbed DEAE-D molecules.Fil: Riva, Julieta Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Yudi, Lidia Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Adsorption–desorption mechanism of a cationic polyelectrolyte based on dimethylaminoethyl polymethacrylates at the water/1,2-dichloroethane interface

The electrochemical behaviour of the cationic polymer Eudragit® E100 at the polarized water/1,2-dichloroethane interface was studied. The voltammetric response was found to be dependent on the pH of the aqueous phase solution, on the nature of the organic electrolyte, and it was also time dependent during multi-cyclic voltammetry experiments. The results suggest that a diffusion process coupled to an adsorption or re-arrangement of E100 molecules at the interface is taking place. From the analysis of the desorption process, it was determined the presence of a strong attractive interaction between the adsorbed species at the interface and the lateral interaction parameter was calculated.Fil: Riva, Julieta Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Beltramo, Dante Miguel. Provincia de Córdoba. Ministerio de Ciencia y Técnica. Centro de Excelencia En Productos y Procesos de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Yudi, Lidia Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Prometrine - humic acids interactions studied at a water/1,2-dichloroethane interface

The interaction of the herbicide prometrine (PROM) with humic acids (HA) in water was analyzed at a pH range between 2.00 to 10.00. For this purpose the transfer current of protons facilitated by PROM across a water/1,2-dichloroethane interface was employed to quantify PROM concentration in absence or in presence of HA. When humic acids were added in increasing amounts to the solution containing PROM, a gradual decrease in current values was observed, evidencing the retention of PROM by HA. This effect was more important at high pH values. From the results it is concluded that the adsorption of PROM is dependent on the pH and HA concentration. At high pH values the herbicide is strongly retained by HA, revealing a strong interaction probably due to the possibility of PROM (neutral species) to access to hydrophobic regions of AH, where van der Waals interactions prevail. The amount of PROM bounded to HA was calculated by subtracting peak current values in presence and in absence of HA and the adsorption isotherm was plotted. The concave or S type curves obtained, indicative of a process with high resistance to adsorption at low concentrations, was fitted with Freundlich isotherm.Fil: Riva, Julieta Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Juárez, Ana Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Yudi, Lidia Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Interaction between Pharmaceutical Drugs and Polymer-Coated Fe3O4 Magnetic Nanoparticles with Langmuir Monolayers as Cellular Membrane Models

Surface modification of magnetic nanoparticles (MNPs) has been reported to play a significant role in determining their interactions with cell membranes. In this research, the interactions between polymer functionalized (chitosan, CHI or diethylamino-ethyl dextran, DEAE-D) Fe3O4 MNPs, pharmaceutical drugs and model cell membranes were investigated by Langmuir isotherms and adsorption measurements. In this study, 1,2-distearoyl-sn-glycerol-3-phosphate (DSPA) phospholipid monolayers were used as cell membrane models. Insertion experiments demonstrate that diclofenac (DCFN) is not absorbed at the air–water interface, whereas triflupromazine (TFPZ) has a MIP (maximum insertion pressure) of 35 m Nm−1. The insertion of composites MNPs:TFPZ or DCFN has larger MIP values, indicating that the MNPs are adsorbed on the monolayer with the drugs. An Fe3O4@CHI:DCFN composite presented an MIP of 39 m Nm−1 and Fe3O4@DEAE-D:DCFN presented an impressive MIP of 67 mNm−1. In the case of TFPZ, the enhancement in the MIP values is also evident, being 42 mNm−1 for Fe3O4@CHI:TFPZ and 40 mNm−1 for Fe3O4@DEAE-D:DCFN composite. All MNPs:drugs composites have MIP values greater than commonly accepted membrane pressure values, indicating that MNPs:drugs can penetrate a cellular membrane. The fact that the composite MNPs:drugs present greater MIP values than separated compounds indicates that polymer-coated MNPs can act as good drug delivery systems

Interaction between Pharmaceutical Drugs and Polymer-Coated Fe₃O₄ Magnetic Nanoparticles with Langmuir Monolayers as Cellular Membrane Models

Surface modification of magnetic nanoparticles (MNPs) has been reported to play a significant role in determining their interactions with cell membranes. In this research, the interactions between polymer functionalized (chitosan, CHI or diethylamino-ethyl dextran, DEAE-D) Fe3O4 MNPs, pharmaceutical drugs and model cell membranes were investigated by Langmuir isotherms and adsorption measurements. In this study, 1,2-distearoyl-sn-glycerol-3-phosphate (DSPA) phospholipid monolayers were used as cell membrane models. Insertion experiments demonstrate that diclofenac (DCFN) is not absorbed at the air–water interface, whereas triflupromazine (TFPZ) has a MIP (maximum insertion pressure) of 35 m Nm−1. The insertion of composites MNPs:TFPZ or DCFN has larger MIP values, indicating that the MNPs are adsorbed on the monolayer with the drugs. An Fe3O4@CHI:DCFN composite presented an MIP of 39 m Nm−1 and Fe3O4@DEAE-D:DCFN presented an impressive MIP of 67 mNm−1. In the case of TFPZ, the enhancement in the MIP values is also evident, being 42 mNm−1 for Fe3O4@CHI:TFPZ and 40 mNm−1 for Fe3O4@DEAE-D:DCFN composite. All MNPs:drugs composites have MIP values greater than commonly accepted membrane pressure values, indicating that MNPs:drugs can penetrate a cellular membrane. The fact that the composite MNPs:drugs present greater MIP values than separated compounds indicates that polymer-coated MNPs can act as good drug delivery systems