Examinando por Autor "Chávez, Ivonne"

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    A preliminary study on electrocatalytic reduction of CO2 using FAC-ReI(CO)3(4,4′-dimethyl-2,2′-bipyridyl)((E)-2-((3-amino-pyridin-4-ylimino)-methyl)-4,6-DI-tert-butylphenol))+ complex
    (Sociedad Chilena de Quimica, 2017) Canales, Juan Carlos; Carreño, Alexander; Oyarzún, Diego; Manríquez, Juan Manuel; Chávez, Ivonne
    Several research to explore the possible conversion of CO2 using rhenium(I) tricarbonyl complexes have been reported the last years. In the present work, we investigated a potential use of fac-Re(CO)3(4,4′-di-methyl-2,2′-bipyridyl)L+ complex (C2), where L is an electron-withdrawing ancillary ligands which present an intramolecular hydrogen bond (IHB), in a preliminary electrocatalytic reduction of CO2. The C2 complex was synthesized and characterized according to reported methods earlier. The cyclic voltammogram profle for the C2 complex were studied in dichloromethane under inert atmosphere, and it shows a typical behavior for an electrocatalytic process, the C2 complex illustrate the electrochemical reaction mechanism corresponds to an electrochemical-chemical-electrochemical pathway (ECE). Also, a Vitreous Carbon plate used as working electrode was employed and modifed by cycling the anodic region of C2 in CH2Cl2 which involve the oxidative redox response for the -NH2 and -OH groups. The voltammogram profle involve shows a polymeric deposit on the plate surface in a CO2 saturated solution (pH=7.0). A strong electrocatalytic discharge of current is obtained with a wave foot of -1.3 V showing that C2 have the potential to be used in electrocatalyst CO2 reduction. © 2017 Sociedad Chilena de Quimica. All Rights Reserved.
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    New Cationic fac-[Re(CO)3(deeb)B2]+ Complex, Where B2 Is a Benzimidazole Derivative, as a Potential New Luminescent Dye for Proteins Separated by SDS-PAGE
    (Frontiers Media S.A., 2021-03) Carreño, Alexander; Gacitúa, Manuel; Solis Céspedes, Eduardo; Páez Hernández, Dayán; Swords, Wesley B.; Meyer, Gerald J.; Preite, Marcelo D.; Chávez, Ivonne; Vega, Andrés; Fuentes, Juan A.
    Sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) can be used to separate proteins based mainly on their size such as in denaturing gels. Different staining methods have been reported to observe proteins in the gel matrix, where the most used dyes are generally anionic. Anionic dyes allow for interactions with protonated amino acids, retaining the dye in the proteins. Fluorescent staining is an alternative technique considered to be sensitive, safe, and versatile. Some anionic complexes based on d6 transition metals have been used for this purpose, where cationic dyes have been less explored in this context. In this work, we synthesized and characterized a new monocationic rhenium complex fac-[Re(CO)3(deeb)B2]+ (where deeb is 4,4′-bis(ethoxycarbonyl)-2,2′-bpy and B2 is 2,4-di-tert-butyl-6-(3H-imidazo[4,5-c]pyridine-2-yl)phenol). We carried out a structural characterization of this complex by MS+, FTIR, 1H NMR, D2O exchange, and HHCOSY. Moreover, we carried out UV-Vis, luminescence, and cyclic voltammetry experiments to understand the effect of ligands on the complex’s electronic structure. We also performed relativistic theoretical calculations using the B3LYP/TZ2P level of theory and R-TDDFT within a dielectric continuum model (COSMO) to better understand electronic transitions and optical properties. We finally assessed the potential of fac-[Re(CO)3(deeb)B2]+ (as well as the precursor fac-Re(CO)3(deeb)Br and the free ligand B2) to stain proteins separated by SDS-PAGE. We found that only fac-[Re(CO)3(deeb)B2]+ proved viable to be directly used as a luminescent dye for proteins, presumably due to its interaction with negatively charged residues in proteins and by weak interactions provided by B2. In addition, fac-[Re(CO)3(deeb)B2]+ seems to interact preferentially with proteins and not with the gel matrix despite the presence of sodium dodecyl sulfate (SDS). In future applications, these alternative cationic complexes might be used alone or in combination with more traditional anionic compounds to generate counterion dye stains to improve the process. © Copyright © 2021 Carreño, Gacitúa, Solis-Céspedes, Páez-Hernández, Swords, Meyer, Preite, Chávez, Vega and Fuentes.
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    Ítem
    Synthesis, characterization and computational studies of (E)-2-{[(2-aminopyridin-3-yl)imino]-methyl}-4,6-di-tert-butylphenol
    (Sociedade Brasileira de Química, 2014) Carreño, Alexander; Vega, Andrés; Zarate, Ximena; Schott, Eduardo; Gacitúa, Manuel; Valenzuela, Ninnette; Preite, Marcelo; Manríquez, Juan M.; Chávez, Ivonne
    (E)-2-{[(2-Aminopyridin-3-yl)imino]-methyl}-4,6-di-tert-butyl-phenol ( 3: ), a ligand containing an intramolecular hydrogen bond, was prepared according to a previous literature report, with modifications, and was characterized by UV-vis, FTIR, 1H-NMR, 13C-NMR, HHCOSY, TOCSY and cyclic voltammetry. Computational analyses at the level of DFT and TD-DFT were performed to study its electronic and molecular structures. The results of these analyses elucidated the behaviors of the UV-vis and electrochemical data. Analysis of the transitions in the computed spectrum showed that the most important band is primarily composed of a HOMO→LUMO transition, designated as an intraligand (IL) charge transfer.