Browsing by Author "Ortega, Daniela E."

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    A first-principles study on the adsorption properties of phosphorene oxide for pollutant removal from water
    (2022) Cortes-Arriagada, Diego; Barria, Natacha; Ortega, Daniela E.; Araya-Duran, Ingrid; Camarada, Maria Belen
    Phosphorene-based materials have emerged as useful platforms for new technological applications, including their potential implementation in the solid-phase extraction of pollutants. In this study, we implemented a first-principles study to characterize the interactions between water-soluble pollutants and phosphorene oxide (PhosO) at the microscopic level, providing useful mechanistic insights into the role of phosphorene oxidation in its adsorption/removal ability. Continuum/explicit solvent effects were considered to explain the solvent role, and the ALMO-EDA method characterizes the intermolecular forces. Our results show that PhosO significantly adsorbs pollutants on its surface by inner surface adsorption, even under aqueous environments, and provides remarkable adsorption stability for a wide family of water-soluble emerging contaminants (pharmaceuticals, endocrine disruptors, flame retardants, and industrial chemicals) with adsorption energies of 0.53 to 1.17 eV. The stabilizing energy in solution is driven by a balanced contribution of dispersion and electrostatic driving forces (up to 83% of the stabilizing energy), overcompensating all the destabilizing effects from the solvation process and Pauli repulsion. Furthermore, PhosO promotes low pollutant mobility from its surface under water molecules, which are not competitive factors in the adsorption process. In addition, simulations under dynamic conditions show that the electrostatic/dispersion governed mechanism remains stable at room conditions for real-life applications (300 K, 1 atm). Finally, a bandgap increase of 0.73 eV is noted in PhosO upon pollutant adsorption, giving a suitable framework for further sensing applications of contaminants by increasing the metallic character of PhosO. These results expand the understanding of the role of phosphorene oxidation for its use as a removal platform in water treatment technologies. (c) 2022 Elsevier B.V. All rights reserved.
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    Neutral and cationic methallyl nickel complexes in alkene activation: a combined DFT, ESI-MS and chemometric approach
    (2021) Trofymchuk, Oleksandra S.; Ortega, Daniela E.; Cortes-Arriagada, Diego; Pereira, Alfredo; Daniliuc, Constantin G.; Klitzke, Clecio F.; Santos, Leonardo S.; Rojas, Rene S.
    Herein, we report a comparative study of ethylene activation and 1-hexene isomerization carried out with isomeric neutral and cationic methallyl nickel complexes L1Ni(eta(3)-C3H5) and [L1Ni(eta(3)-C3H5)][B(Ar-F)(4)] in the presence of borane co-catalysts. To understand the reactivity of the nickel complexes with NacNac ligands, we used chemometric methods to classify different catalysts reported to date. The mechanism of the interaction of [L1Ni(eta(3)-C3H5)][B(Ar-F)(4)]/B(C6F5)(3) with 1-hexene was studied by ESI-MS which allowed the detection of cationic species formed in situ. Moreover, there is a very small difference in reactivities from combination of nickel complexes and borane co-catalysts used for alkene isomerization, while the reactivity with ethylene of both systems is very different; [L1Ni(eta(3)-C3H5)][B(Ar-F)(4)]/B(C6F5)(3) produces butene, while L1Ni(eta(3)-C3H5)/B(C6F5)(3) forms polyethylene. Furthermore, DFT studies revealed that the origin of the catalytic activity in the cationic and neutral methallyl nickel complexes co-activated by B(C6F5)(3) is mainly from direct steric effects of the ligand-nickel center where the conformation of the chelate ring is affected by the catalyst symmetry. This work demonstrates how the cationic or neutral nature of the same system affects its catalytic and structural properties.
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    The interaction mechanism of polystyrene microplastics with pharmaceuticals and personal care products
    (2023) Cortes-Arriagada, Diego; Miranda-Rojas, Sebastian; Camarada, Maria Belen; Ortega, Daniela E.; Alarcon-Palacio, Victoria B.
    Microplastics (MPs) have been detected in the hydrosphere, with hazardous implications in transporting coexisting water pollutants. Our knowledge about the interaction mechanisms that MPs establish with organic pollutants are still growing, which is essential to understand the adsorption properties of MPs and their relative stability with adsor-bates. Here, we used classical (force field methods) and ab-initio (density functional theory) computational chemistry tools to characterize the interaction mechanisms between Polystyrene-MPs (PS-MPs) and pharmaceuticals/personal care products (PPCPs). Adsorption conformations and energies, thermochemistry, binding, and energy decomposition analyses were performed to obtain the quantitative mechanistic information. Our results show that PS-MPs have per-manent dipoles, increasing the interaction with neutral PPCPs while repelling the charged pollutants; in all cases, a sta-ble physisorption takes place. Moreover, PS-MPs increase their solubility upon pollutant adsorption due to an increase in the dipole moment, increasing their co-transport ability in aqueous environments. The stability of the PS-MPs/ PPCPs complexes is further confirmed by thermochemical and molecular dynamics trajectory analysis as a function of temperature and pressure. The interaction mechanism of high pKa pollutants (pKa > 5) is due to a balanced contri-bution of electrostatic and dispersion forces, while the adsorption of low pKa pollutants (pKa < 5) maximizes the elec-trostatic forces, and steric repulsion effects explain their relative lower adsorption stability. In this regard, several pairwise intermolecular interactions are recognized as a source of stabilization in the PS-MPs/PPCPs binding: hydro-gen bonding, pi-pi, O\\HMIDLINE HORIZONTAL ELLIPSIS pi, and C\\HMIDLINE HORIZONTAL ELLIPSIS pi, C\\ClMIDLINE HORIZONTAL ELLIPSISC\\H and C\\HMIDLINE HORIZONTAL ELLIPSISC\\H interactions. The ionic strength in solution slightly affects the adsorption stability of neutral PPCPs, while the sorption of charged pollutants is enhanced. This mechanistic information provides quantitative data for a better understanding of the interactions between organic pol-lutants and MPs, serving as valuable information for sorption/kinetic studies.