Browsing by Author "Hidalgo-Rosa, Yoan"

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    Exploring the adsorption of five emerging pollutants on activated carbon: A theoretical approach
    (2024) Gonzalez-Rodriguez, Lisdelys; Yanez, Osvaldo; Mena-Ulecia, Karel; Hidalgo-Rosa, Yoan; Garcia-Carmona, Ximena; Ulloa-Tesser, Claudia
    The identification and management of contaminants of emerging concern (CECs) in water systems is crucial for protecting public and environmental health. This paper reports a theoretical approach to studying the adsorption of five CECs: Atrazine (ATZ), Caffeine (CAF), Carbamazepine (CBZ), Sulfamethoxazole (SMX), and Ibuprofen (IBU) - onto Activated Carbon (AC). A set of computational methods, including electrostatic molecular potential maps, conceptual density functional theory, Fukui functions, thermodynamic analysis, and tight-binding molecular dynamics simulations, were employed to analyze the electronic/energetic interactions and mechanisms involved in the adsorption of CECs on AC. The theoretical methodology offered valuable predictions on reactivity sites, stability, and binding mechanisms. Results showed that adsorption primarily occurred through non-covalent interactions like pi-pi electron donor-acceptor interactions, van der Waals forces, and hydrophobic interactions. Thermodynamic properties suggested the adsorption process was spontaneous and exothermic. However, for the AC/SMX system, the Gibbs free energy reveals that adsorption may be unfavorably compared to the other study systems. Molecular dynamics simulations validated the kinetic stability in the following order CAF (0.13 & Aring;)>CBZ (0.23 & Aring;)>ATZ (0.75 & Aring;)> IBU (1.28 & Aring;)>SMX (1.54 & Aring;). This exploratory theoretical study provides a deep understanding of the interactions between AC and five CECs, aiding in the rational design and optimization of AC-based treatment systems for environmental and industrial applications.
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    Quantum chemical elucidation of the luminescence mechanism in a europium(iii) co-doped UiO-66 chemosensor selective to mercury(ii)
    (2025) Hidalgo-Rosa, Yoan; Echevarría-Valdés, Yoslainy; Saavedra-Torres, Mario; Paez-Hernández, Dayán; Schott Verdugo, Eduardo Enrique; Zárate, Ximena
    Lanthanide(iii) ions can be incorporated into metal-organic frameworks (MOFs) to form Ln@MOFs through post-synthetic procedures. This makes the MOFs efficient luminescent chemical sensors for detecting trace amounts of heavy metals. In this report, a quantum chemical theoretical protocol has been carried out to elucidate the detection principle of the turn-off luminescence mechanism in a Eu@UiO-66(DPA)-type MOF selective to Hg2+ ions. UiO-66(DPA) is an iso-reticular MOF of UiO-66 constructed from the Zr6-cluster [Zr6(μ3-O)4(μ3-OH)4]12+ and the ligands 1,4-benzenedicarboxylate (BDC) and 2,6-pyridinedicarboxylate (DPA) as linkers. The sensitization and energy transfer (ET) in UiO-66(DPA) doped with Eu3+ were analyzed using multireference ab initio CASSCF/NEVPT2 methods and time-dependent density functional theory (TD-DFT). The cluster model used in the calculations comprises the Z6-cluster/BDC/DPA fragments with the DPA ligand coordinating to Eu3+ or Hg2+ ions. The proposed sensitization pathway involves intersystem crossing from S1(DPA) to T1(DPA), a plausible subsequent energy transfer from T1(DPA) to the 5D1 state of Eu3+, and then vibrational relaxation to the emissive 5D0 state. These results also suggest that the electronic states of the BDC ligand can be strengthened by the population of the T1 electronic states of the DPA antenna via ET. Periodic DFT calculations confirm the electronic state mixture of BDC and DPA linkers in the conduction bands, just above the electronic state of Eu3+ ions, which is in concordance with the proposed Eu3+ sensitization pathways. The assessed optical properties (absorption and emission) of Hg2+@UIO-66(DPA) explain the experimental behavior of this chemosensor when the Hg2+ ion replaces the Eu3+ ion and the luminescence diminishes.
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    Tunning the optical properties of a photocatalytic metal-organic framework by means of molecular modelling
    (2023) Treto-Suarez, Manuel A.; Hidalgo-Rosa, Yoan; Ulecia, Karel Mena; Paez-Hernandez, Dayan; Koivisto, Bryan D.; Zarate, Ximena; Schott, Eduardo
    A theoretical study of reported isostructural metal-organic frameworks (MOFs) based on MIL-125-Ti4+ was performed to understand the optical properties and facilitate the rational design of new materials with potentially improved features as photocatalysts. The experimentally tested MOFs (MIL-125-Ti4+ labeled as M) were functionalized with -NH2, -CH3, and -OH substituents on the 1,4-benzene-dicarboxylate (BDC) linker (labeled as M-NH2, M-CH3, and M-OH, respectively), generating a broadened light-harvesting of the MOF and an improvement of the N-2 conversion rate. The M-NH2 showed the highest visible light absorption and N-2 photocatalysis efficiency experimentally. This substituent effect was theoretically studied via Density Functional Theory (DFT) calculations on the ground singlet (S-0) and first excited state (singlet and triplet) using Time-Dependent Density Functional Theory (TD-DFT), the Morokuma-Ziegler energy decomposition scheme, and Natural Orbital of Chemical Valence (NOCV) analysis. These tools allowed for the reproduction of the optical properties and performance in good agreement with the experiment and highlight that the N-2 conversion rate increases as the donor character of the R group improve. This effect is a result of the stabilization of the Occupied Molecular Orbitals (localized on the BDC linker), a decrease in the charge recombination, and by an increase of charge flow to the metal center favoring the photocatalytic Ti4+/Ti3+ reduction (via ligand to metal charge transfer (LMCT) transition). These systems also display a metal-ligand charge transfer (MLCT) process in the excited state favoring the emission localized in the BDC linker, which was confirmed via Complete Active Space Self-Consistent Field (CASSCF) calculation. Finally, through CASSCF, it was possible to propose two new isoreticular structures, with the -SH and -NO2 substituents (labeled as M-SH and M-NO2), with the -SH variant exhibiting optical and photocatalytic properties that could rival M with -NH2 substitution.