Browsing by Author "Barrias, Pablo"

Now showing 1 - 6 of 6
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    Aggregation of alpha- and beta- caseins induced by peroxyl radicals involves secondary reactions of carbonyl compounds as well as di-tyrosine and di-tryptophan formation
    (2018) Fuentes Lemus, Eduardo Felipe; Silva, Eduardo; Barrias, Pablo; Aspee, Alexis; Escobar Álvarez, Elizabeth; Lorentzen, Lasse G.; Carroll, Luke; Leinisch, Fabian; Davies, Michael J.; López Alarcón, Camilo Ignacio
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    Atypical antioxidant activity of non-phenolic amino-coumarins
    (2018) Zuniga-Nunez, Daniel; Barrias, Pablo; Cardenas-Jiron, Gloria; Soledad Ureta-Zanartu, M.; López Alarcón, Camilo Ignacio; Moran Vieyra, F. Eduardo; Borsarelli, Claudio D.; Alarcon, Emilio I.; Aspee, Alexis
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    Cover Picture: Electron Spin-Dependent Electrocatalysis for the Oxygen Reduction Reaction in a Chiro-Self-Assembled Iron Phthalocyanine Device (Angew. Chem. Int. Ed. 4/2024)
    (2024) Scarpetta-Pizo, Laura; Venegas, Ricardo; Barrias, Pablo; Munoz-Becerra, Karina; Vilches-Labbe, Nayareth; Mura, Francisco; Mendez-Torres, Ana Maria; Ramirez-Tagle, Rodrigo; Toro-Labbe, Alejandro; Hevia, Samuel; Zagal, Jose H.; Onate, Ruben; Aspee, Alexis; Ponce, Ingrid
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    Electrodes based on zeolites modified with cobalt and/or molybdenum for pesticide degradation: part II-2,4,6-trichlorophenol degradation
    (2021) Castro, Jorge; Fernandez, Francisco; Olivares, Felipe; Berrios, Cristhian; Garrido-Ramirez, Elizabeth; Blanco, Elodie; Escalona, Nestor; Aspee, Alexis; Barrias, Pablo; Soledad Ureta-Zanartu, M.
    2,4,6-trichlorophenol (TCP) is a persistent pollutant introduced in water by industrial processes and pesticides. We have studied the electrooxidation of TCP on glassy carbon (GC) electrodes drop-coated with a suspension containing Mo- and/or Co-modified zeolite, graphite, and Nafion (R) perfluorinated ion-exchange resin in distilled water. Three zeolites, Linde type A (ZA), Faujasite (ZY) and MFI (ZSM-5), of different hydrophilic/hydrophobic character, were modified with molybdenum and/or cobalt by the wet impregnation method and characterized by Fourier-transform infrared spectroscopy with attenuated total reflection and temperature programmed reduction. The electrochemical study included cyclic voltammetry, electrochemical impedance spectroscopy, and electrolysis at controlled potential. High performance liquid chromatography and mass spectrometry allowed detecting the following reaction products: 2,6-dichloro-1,4-benzoquinone, 2,6-dichloro-1,4-hydroquinone, 3,5-dichloro-2-hydroxy-1,4-benzoquinone, and malic, maleic, picric, and acetic acids. A maximum degradation of about 90% was reached after 4 h of electrolysis at 0.83 V vs Ag/AgCl/KCl 3 M, using a GC/graphite-ZSM5(Mo) electrode. The electrodes modified with Mo, and especially that with ZSM5, the most hydrophobic zeolite, were active for the degradation of TCP. We conclude that the main role of the Mo species is to catalyze the hydrogen peroxide decomposition yielding reactive singlet oxygen, as evidenced by the pink color of 3,5-dichloro-2-hydroxy-1,4-benzoquinoneand confirmed by mass spectrometry.
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    Electron Spin-Dependent Electrocatalysis for the Oxygen Reduction Reaction in a Chiro-Self-Assembled Iron Phthalocyanine Device
    (2023) Scarpetta-Pizo, Laura; Venegas, Ricardo; Barrias, Pablo; Munoz-Becerra, Karina; Vilches-Labbe, Nayareth; Mura, Francisco; Mendez-Torres, Ana Maria; Ramirez-Tagle, Rodrigo; Toro-Labbe, Alejandro; Hevia, Samuel; Zagal, Jose H.; Onate, Ruben; Aspee, Alexis; Ponce, Ingrid
    The chiral-induced spin selectivity effect (CISS) is a breakthrough phenomenon that has revolutionized the field of electrocatalysis. We report the first study on the electron spin-dependent electrocatalysis for the oxygen reduction reaction, ORR, using iron phthalocyanine, FePc, a well-known molecular catalyst for this reaction. The FePc complex belongs to the non-precious catalysts group, whose active site, FeN4, emulates catalytic centers of biocatalysts such as Cytochrome c. This study presents an experimental platform involving FePc self-assembled to a gold electrode surface using chiral peptides (L and D enantiomers), i.e., chiro-self-assembled FePc systems (CSAFePc). The chiral peptides behave as spin filters axial ligands of the FePc. One of the main findings is that the peptides ' handedness and length in CSAFePc can optimize the kinetics and thermodynamic factors governing ORR. Moreover, the D-enantiomer promotes the highest electrocatalytic activity of FePc for ORR, shifting the onset potential up to 1.01 V vs. RHE in an alkaline medium, a potential close to the reversible potential of the O2/H2O couple. Therefore, this work has exciting implications for developing highly efficient and bioinspired catalysts, considering that, in biological organisms, biocatalysts that promote O2 reduction to water comprise L-enantiomers.
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    Riboflavin-induced Type 1 photo-oxidation of tryptophan using a high intensity 365 nm light emitting diode
    (2019) Silva, Eduardo; Barrias, Pablo; Fuentes Lemus, Eduardo Felipe; Tirapegui, Cristian; Aspee, Alexis; Carroll, Luke; Davies, Michael J.; López Alarcón, Camilo Ignacio