Browsing by Author "Toro Labbé, Alejandro Miguel"

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    Chemiluminescence emission in fenton reaction driven by 1,2-dihydroxybenzenes: Mechanistic approaches using 4-substituted ligands
    (2021) Romero, Romina; Marquéz, Katherine; Benítez Olivares, Francisca Javiera; Toro Labbé, Alejandro Miguel; Cornejo Ponce, Lorena; Melín, Victoria; Contreras, David
    Fenton (F) and Fenton-like (FL) reactions can be amplified by dihydroxybenzenes (DHBs). These compounds chelate and reduce Fe(III), promoting the hydroxyl radical production ((OH)-O-center dot). The products or intermediaries of F and FL reactions driven by DHBs can produce chemiluminescence (CL) with different profiles, depending on the type of DHB involved. In this work, CL produced by F and FL systems driven by different -para substituted DHBs was measured and compared with the reactivity of each system and with the structural parameters of each DHB. CL emission was not related to the reactivity of each studied system but was favored by DHBs substituents with -NHR and -OH groups combined in the branching (NHR-DHBs). PLS multivariate regression models were constructed using computational parameters for each DHB, quinone (Q) and semiquinone (SQ(center dot)) to find the influence of structural and electronic parameters over CL emission. Analysis showed that in NHR-DHBs, the higher CL exhibited could be explained by cycling ability of these compounds. In DHBs with an electron-donor group (EDG) the CL emission would depend only on the stability of the intermediary species generated by DHB and (OH)-O-center dot reaction. While DHBs with electron-withdrawing groups (EWG) showed that CL will increase depending on the stability of the intermediaries by resonance, and by the acidity of the hydroxyl protons of the ring. PLS-SQ(center dot) showed that spin densities were strongly correlated with an increase in CL emission. DHBs with substituents that favor the delocalization of charge in the SQ(center dot) to the ramification would enhance CL emission. Meanwhile, when the delocalization is promoted over the DHB-ring, these systems become more reactive, and the CL emission is disadvantaged by quinone formation.
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    DFT Study of Oxygen Adsorption by Single-Atom Catalysts on N-Doped Graphene: Implications for Oxygen Reduction Reactions
    (2025) Alvarado-Leal, Luis Angel; Perez-Tijerina, Eduardo Gerardo; Fernandez-Escamilla, Hector Noé; Romo-Herrera, José Manuel; Takeuchi, Noboru; Toro Labbé, Alejandro Miguel
    This study investigates the influence of transition metal magnetic moments on the adsorption and reactivity of molecular oxygen (O2) in nitrogen-doped graphene-supported single-atom catalyst systems using density functional theory calculations. We demonstrate that metals with higher magnetic moments, such as Cr and Mn, exhibit enhanced affinity and stabilization of O2 adsorption. In contrast, metals with lower or null magnetic moments, like Ni and Cu, show diminished capability to adsorb O2 effectively. Our analysis of adsorption energies, Morse potential depths, and reaction force underscores the critical role of transition metal magnetic moments in dictating catalytic performance and characterizing the nature of the chemical bond between the metal center and oxygen. It has been found that the strength of the oxygen–metal bond as well as its electronic activity are crucial elements that can be used to enhance the catalytic effect in capturing O2. This provides insights for optimizing single-atom catalysts (SACs) in oxygen reduction reactions and other energy conversion applications.
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    Foreword for the Festschrift on the occasion of the 65th birthday of Professor Pratim Kumar Chattaraj
    (Springer-Verlag GmbH Germany, 2024) Proft, Frank de; Ayers, Paul W.; Liu, Shubin; Toro Labbé, Alejandro Miguel; Sarkar, Utpal