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1.
Org Biomol Chem ; 22(10): 1993-1997, 2024 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-38372038

RESUMEN

A solventless and acid-catalyzed condensation of meso-perfluoroalkyl-dipyrromethanes with selected benzaldehydes was used to prepare ten different bilanes that were isolated before their oxidation into trans-A2B-corroles bearing two meso-perfluoroalkyl groups. Macrocycles bearing long chains (C3F7 or C7F15) are key precursors to afford ABC-corroles having a meso-acyl substituent when subjected to a mild and basic hydrolysis affecting one of the alkyl substituents.

2.
Mol Ther ; 31(7): 2240-2256, 2023 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-37016577

RESUMEN

Alteration in the buffering capacity of the proteostasis network is an emerging feature of Alzheimer's disease (AD), highlighting the occurrence of endoplasmic reticulum (ER) stress. The unfolded protein response (UPR) is the main adaptive pathway to cope with protein folding stress at the ER. Inositol-requiring enzyme-1 (IRE1) operates as a central ER stress sensor, enabling the establishment of adaptive and repair programs through the control of the expression of the transcription factor X-box binding protein 1 (XBP1). To artificially enforce the adaptive capacity of the UPR in the AD brain, we developed strategies to express the active form of XBP1 in the brain. Overexpression of XBP1 in the nervous system using transgenic mice reduced the load of amyloid deposits and preserved synaptic and cognitive function. Moreover, local delivery of XBP1 into the hippocampus of an 5xFAD mice using adeno-associated vectors improved different AD features. XBP1 expression corrected a large proportion of the proteomic alterations observed in the AD model, restoring the levels of several synaptic proteins and factors involved in actin cytoskeleton regulation and axonal growth. Our results illustrate the therapeutic potential of targeting UPR-dependent gene expression programs as a strategy to ameliorate AD features and sustain synaptic function.


Asunto(s)
Enfermedad de Alzheimer , Animales , Ratones , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/terapia , Enfermedad de Alzheimer/metabolismo , Estrés del Retículo Endoplásmico/genética , Ratones Transgénicos , Proteómica , Proteostasis/genética , Transducción de Señal/fisiología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Respuesta de Proteína Desplegada/genética
3.
Chemistry ; 29(25): e202203175, 2023 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-36602462

RESUMEN

Non-covalent hybrid materials based on graphene and A3 -type copper corrole complexes were computationally investigated. The corroles complexes contain strong electron-withdrawing fluorinated substituents at the meso positions. Our results show that the non-innocent character of corrole moiety modulates the structural, electronic, and magnetic properties once the hybrid systems are held. The graphene-corrole hybrids displayed outstanding stability via the interplay of dispersion and electrostatic driving forces, while graphene act as an electron reservoir. The hybrid structures exposed an intriguing magneto-chemical performance, compared to the isolated counterparts, that evidenced how structural and electronic effects contributed to the magnetic response for both ferromagnetic and antiferromagnetic cases. Directional spin polarization and spin transfer from the corrole to the graphene surface participate in the amplification. Finally, there are relations between the spin transfer, the magnetic response, and the copper distorted ligand field, offering exciting hints about modulating the magnetic response. Therefore, this work shows that copper corroles emerged as versatile building blocks for graphene hybrid materials, especially in applications requiring a magnetic response.

4.
J Phys Chem A ; 124(18): 3662-3671, 2020 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-32272841

RESUMEN

To search for new uptake platforms for the removal of highly toxic and mobile arsenite [or trivalent arsenic, As(OH)3], we theoretically investigate the adsorption properties of intrinsic and metal-doped phosphorene nanoadsorbents. The doping of phosphorene with Ni or Cu atoms remarkably increases the uptake stability of arsenite at water environments compared to intrinsic phosphorene, with a weak competition of H2O molecules by the adsorption sites, where the adatom doping of phosphorene allows obtaining better uptake performance compared to the substitutional doping. The uptake is explained by a strong inner-sphere surface complexation, which is dominated by permanent electrostatic physical effects. Hydroxide anions show strong competitive adsorption compared to H2O and arsenite; thus, the straightforward recovery of the nanoadsorbents could be reached after removal by treatment at high pH solutions. Therefore, metal-doped phosphorene hybrids could serve as superior nanoadsorbents for arsenic separation from water by adsorption in solid phases.

5.
J Org Chem ; 83(11): 5969-5974, 2018 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-29486121

RESUMEN

The reaction electronic flux (REF) offers a powerful tool in the analysis of reaction mechanisms. Noteworthy, the relationship between aromaticity and REF can eventually reveal subtle electronic events associated with reactivity in aromatic systems. In this work, this relationship was studied for the triplet Zimmerman di-π-methane rearrangement. The aromaticity loss and gain taking place during the reaction is well acquainted by the REF, thus shedding light on the electronic nature of reactions involving dibenzobarrelenes.

6.
Phys Chem Chem Phys ; 20(35): 22915-22925, 2018 Sep 12.
Artículo en Inglés | MEDLINE | ID: mdl-30152509

RESUMEN

The mechanism of ethylene polymerization by means of neutral methallyl-Ni(ii) complexes has been studied by quantum chemical calculations. Two isomer complexes having different ligand functionalization at the ortho or para position, and co-activated with trispentafluorephenylborane [B(C6F5)3], were studied according to the Cossee-Arlman's mechanism. Comparison of the reaction mechanism of both isomers shows that energy barriers strongly depend on ligand-functionalization and are mostly due to structural rearrangements. In addition, it was found that para-functionalization can be distinguished by favorable σ-donation whereas ortho-functionalization is more prone to a π back-donation process. Our results concerning the polymerization process for ortho and para isomers not only provide a theoretical perspective of available experimental data, but also explain the experimentally observed higher molecular weight of the methallyl-Ni(ii) ortho isomer co-catalyzed by B(C6F5)3, revealing the role of ligand-functionalization in polyethylene production.

7.
Chemistry ; 23(42): 10167-10176, 2017 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-28543880

RESUMEN

A detailed quantum chemical study that analyzed the mechanism of ethylene oligomerization and polymerization by means of a family of four neutral methallyl NiII catalysts is presented. The role of the boron co-activators, BF3 and B(C6 F5 )3 , and the position of ligand functionalization (ortho or para position of the N-arylcyano moiety of the catalysts) were investigated to explain the chain length of the obtained polymers. The chain initialization proceeded with higher activation barriers for the ortho-functionalized complexes (≈19 kcal mol-1 ) than the para-substituted isomers (17-18 kcal mol-1 ). Two main pathways were revealed for the chain propagation: The first pathway was favored when using the B(C6 F5 )3 co-activated catalyst, and it produced long-chain polymers. A second pathway led to the ß-hydrogen complexes, which resulted in chain oligomerization; this pathway was preferred when the BF3 co-activated catalysts were used. Otherwise, the termination of longer chains occurred via a stable hydride intermediate, which was formed with an energy barrier of about 14 kcal mol-1 for the B(C6 F5 )3 co-activated catalysts. Significant new insights were made into the reaction mechanism, whereby neutral methallyl NiII catalysts act in oligomerization and polymerization processes. Specifically, the role of co-activation and ligand functionalization, which are key information for the further design of related catalysts, were revealed.

8.
Photochem Photobiol Sci ; 16(8): 1268-1276, 2017 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-28636041

RESUMEN

In this paper, we explored the fluorescence properties of eight aurone derivatives bearing methoxy groups and bromine atoms as substituents in the benzene rings. All derivatives showed strong solvatochromic absorption and emission properties in solvents of different polarities. Some of them showed high fluorescence quantum yields, which make them potential compounds for sensing applications. The position of the methoxy groups in the benzofuranone moiety and the presence of bromine atoms in the benzene ring had a strong influence on the fluorescence behaviour of the aurones. DFT calculations allowed us to explain the emission properties of aurones and their solvatochromism, which was related to an excited state with strong charge-transfer character. Aurone 4 has the most promising characteristics showing a large difference in the quantum yields and large Stokes shifts depending on the solvent polarities. These results prompted us to explore some preliminary biological applications for aurone 4 such as the sensing of hydrophobic pockets of a protein and its thermotropic behaviour in liposomes.


Asunto(s)
Benzofuranos/química , Modelos Teóricos , Benzofuranos/metabolismo , Humanos , Liposomas/química , Liposomas/metabolismo , Teoría Cuántica , Albúmina Sérica Humana/química , Albúmina Sérica Humana/metabolismo , Solventes/química , Espectrometría de Fluorescencia
9.
Phys Chem Chem Phys ; 19(6): 4179-4189, 2017 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-27990518

RESUMEN

The interaction of formaldehyde (H2CO) onto Fe-doped graphene (FeG) was studied in detail from density functional theory calculations and electronic structure analyses. Our aim was to obtain insights into the adsorption, desorption and sensing properties of FeG towards H2CO, a hazardous organic compound. The adsorption of H2CO was shown to be energetically stable onto FeG, with adsorption energies of up to 1.45 eV and favored in different conformations. This interaction was determined to be mostly electrostatic in nature, where the oxygen plays an important role in this contribution; besides, our quantum molecular dynamics results showed the high stability of the FeG-H2CO interaction at ambient temperature (300 K). All the interactions were determined to be accompanied by an increase in the HOMO-LUMO energy gap with respect to the isolated adsorbent, indicating that FeG is highly sensitive to H2CO with respect to pristine graphene. Finally, it was found that external electric fields of 0.04-0.05 a.u. were able to induce the pollutant desorption from the adsorbent, allowing the adsorbent reactivation for repetitive applications. These results indicate that FeG could be a promising candidate for adsorption/sensing platforms of H2CO.

10.
Phys Chem Chem Phys ; 19(27): 17587-17597, 2017 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-28656190

RESUMEN

Graphene-based materials have emerged as new potential adsorbents for the adsorption and removal of persistent pollutants, and they could play a key role in the remediation of 1,4-dioxane. In this framework, a quantum chemistry study was carried out to rationalize the sorption properties of oxidized graphene (GO) and Si-doped graphene (SiG) nanosheets for use in 1,4-dioxane removal, taking into account that these adsorbents are experimentally available. Dispersion corrected PBE-D3/SVP calculations show that GO and SiG adsorbs dioxane through non-covalent and covalent interactions, respectively, with adsorption energies of up to ∼0.9 eV, which represents an important improvement with respect to the adsorption onto intrinsic graphene. The adsorption strength was also rationalized in terms of natural bond orbitals, atoms-in-molecules and energy decomposition analyses. In the case of GO, a high content of hydroxyl and carboxyl functional groups enhances the removal efficiency, and they are responsible for the high adsorption stability in aqueous environments and at room temperature (300 K). In addition, explicit/implicit solvent calculations and molecular dynamics trajectories show that the SiG-dioxane interaction is highly stable at 300 K, without pollutant diffusion; besides, the SiG-dioxane interaction is stabilized in the presence of H2O molecules. All the analyses suggest that GO and SiG should be considered as new remarkable candidates for sorption technologies related to the removal, control and remediation of 1,4-dioxane, where the sorption efficiency is sorted as SiG > GO ≫ G.

11.
Phys Chem Chem Phys ; 18(47): 32281-32292, 2016 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-27849092

RESUMEN

The potential applications of Al, Ti, Mn and Fe-doped graphene for environmental remediation of 1,4-dioxane (a critical pollutant and toxic compound) are analyzed in detail in the framework of density functional theory calculations. 1,4-Dioxane is a highly mobile and soluble pollutant and developing new strategies for its adsorption and subsequent removal becomes an important issue. All the systems were fully optimized and analyzed in their most stable spin states. The results determined that the proposed doped-graphene materials enhance the interaction with 1,4-dioxane compared to intrinsic graphene, with adsorption energies in the range of 1.2-1.6 eV. The high stability of the adsorbent-dioxane interactions is fully discussed in terms of chemical metal-dioxane binding, charge transfer and long-range interactions. The adsorbent-dioxane adsorption is also accompanied by changes in the electronic structure with respect to the isolated substrates, which are larger for Mn and Fe as dopants. Ab initio molecular dynamics simulations also show that the adsorbent-adsorbate interactions remain strong at room temperature (300 K). Finally, implicit/explicit solvent methodologies were implemented to get insights into the effects of aqueous environments on the adsorption strength, which shows the high stability of interaction in water, sorting the sorption efficiency as AlG ≈ FeG > MnG ≈ TiG. From these new insights, Al, Ti, Mn and Fe-doped graphene emerge as new potential materials to be applied in technologies related to the removal of 1,4-dioxane.

12.
Phys Chem Chem Phys ; 18(2): 726-34, 2016 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-26449274

RESUMEN

A family of cyclometalated Ir(III) complexes was studied through quantum chemistry calculations to get insights into their applicability in light electrochemical cells (LECs). The complexes are described as [Ir(R-C^N)2(ppl)](+), where ppl is the pyrazino[2,3-f][1,10]-phenanthroline ancillary ligand. The modification of the HOMO energy in all the complexes was achieved by means of different R-C^N cyclometalating ligands, with R-ppy (phenylpyridine), R-pyz (1-phenylpyrazole) or R-pypy (2,3'-bipyridine); in addition, inductive effects were taken into account by substitution with the R groups (R = H, F or CF3). Then, compounds with HOMO-LUMO energy gaps from 2.76 to 3.54 eV were obtained, in addition to emission energies in the range of 438 to 597 nm. The emission deactivation pathways confirm the presence of metal-to-ligand transitions in all the complexes, which allow the strong spin-orbit coupling effects, and then improving the luminescence performance. However, the coupling with ligand and metal centered excited states was observed for the blue-shifted emitters, which could result in a decrease of the luminescence efficiencies. Furthermore, ionization potentials, electron affinities and reorganization energies (for holes and electrons) were obtained to account for the injection and transport properties of all the complexes in electroluminescent devices.

13.
Phys Chem Chem Phys ; 17(18): 12056-64, 2015 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-25873031

RESUMEN

On the basis of quantum chemistry calculations, the adsorption of As(III) onto graphene based adsorbents has been studied. The energetic and molecular properties that characterize the adsorption have been analyzed, and new adsorbents were proposed. The experimentally reported inefficient adsorption of As(III) by intrinsic graphene is theoretically characterized by a low adsorption energy (∼0.3 eV), which is decreased by solvent effects. Two stable conformations were found for the adsorbent-adsorbate systems. The As(III) removal by unmodified oxidized graphene (GO) reaches a medium size adsorption strength (<∼0.8 eV), while still remaining low for high removal efficiency from a water environment. While As(III) adsorption onto boron, nitrogen and phosphorous doped graphene is not favored with respect to the pristine adsorbent, aluminium, silicon and iron embedded graphene can adsorb As(III) by both chemical and physical interactions with high adsorption energies (>∼1 eV), even stable considering a solvent environment. The efficiency of the adsorbents for As(III) removal is sorted as Al-G > Fe-G ≫ Si-G ≫ GO ≫ G. Therefore, Al, Si and Fe doped graphene are considered as potential materials for efficient As(III) removal.

14.
J Phys Chem A ; 119(26): 6909-18, 2015 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-26061641

RESUMEN

The interaction of arsenic(III) onto the tetrahedral Au20 cluster was studied computationally to get insights into the interaction of arsenic traces (presented in polluted waters) onto embedded electrodes with gold nanostructures. Pollutant interactions onto the vertex, edge, or inner gold atoms of Au20 were observed to have a covalent character by forming metal-arsenic or metal-oxygen bonding, with adsorption energies ranging from 0.5 to 0.8 eV, even with a stable physisorption; however, in aqueous media, the Au-vertex-pollutant interaction was found to be disadvantageous. The substituent effect of a platinum atom onto the Au20 cluster was evaluated to get insights into the changes in the adsorption and electronic properties of the adsorbent-adsorbate systems due to chemical doping. It was found that the dopant atom increases both the metal-pollutant adsorption energy and stability onto the support in a water media for all interaction modes; adsorption energies were found to be in a range of 0.6 to 1.8 eV. All interactions were determined to be accompanied by electron transfer as well as changes in the local reactivity that determine the amount of transferred charge and a decrease in the HOMO-LUMO energy gap with respect to the isolated substrate.


Asunto(s)
Arsénico/química , Oro/química , Platino (Metal)/química , Adsorción , Simulación por Computador , Monitoreo del Ambiente , Enlace de Hidrógeno , Modelos Químicos , Estructura Molecular , Solventes/química , Agua/química , Contaminantes Químicos del Agua/química
15.
J Chem Phys ; 141(13): 134701, 2014 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-25296822

RESUMEN

At the PBE-D3/cc-pVDZ level of theory, the hydrogen chemisorption on graphene was analyzed using the reaction force and reaction electronic flux (REF) theories in combination with electron population analysis. It was found that chemisorption energy barrier is mainly dominated by structural work (∼73%) associated to the substrate reconstruction whereas the electronic work is the greatest contribution of the reverse energy barrier (∼67%) in the desorption process. Moreover, REF shows that hydrogen chemisorption is driven by charge transfer processes through four electronic events taking place as H approaches the adsorbent surface: (a) intramolecular charge transfer in the adsorbent surface; (b) surface reconstruction; (c) substrate magnetization and adsorbent carbon atom develops a sp(3) hybridization to form the σC-H bond; and (d) spontaneous intermolecular charge transfer to reach the final chemisorbed state.

16.
J Mol Model ; 30(8): 278, 2024 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-39034330

RESUMEN

CONTEXT: This study investigates the ethylene insertion reaction mechanism for polymerization catalysis, aiming to discern differences between Ni-α-imine ketone-type catalyst and their SiO2-supported counterpart. The reaction force analysis unveils a more intricate mechanism with SiO2 support, shedding light on unexplored factors and elucidating the observed lower catalytic activity. Furthermore, reactivity indexes suggest earlier ethylene activation in the supported catalyst, potentially enhancing overall selectivity. Finally, the reaction electronic flux analysis provides detailed insights into the electronic activity at each step of the reaction mechanism. In sum, this study offers a comprehensive understanding of the ethylene insertion reaction mechanism in both molecular and supported catalysts, underscoring the pivotal role of structural and electronic factors in catalytic processes. METHODS: Density functional theory (DFT) calculations were conducted using the ωB97XD functional and the 6-31 + G(d,p) basis sets with Gaussian16 software. Computational techniques utilized in this study encompassed the IRC method, reaction force analysis, and evaluation of electronic descriptors such as electronic chemical potential, molecular hardness, and electrophilicity reactivity indexes. Additionally, reaction electronic flux analysis was employed to investigate electronic activity along the reaction coordinate.

17.
Chemosphere ; 350: 141147, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38195016

RESUMEN

Nanoplastics (NPLs) persist in aquatic habitats, leading to incremental research on their interaction mechanisms with metalloids in the environment. In this regard, it is known that plastic debris can reduce the number of water-soluble arsenicals in contaminated environments. Here, the arsenic interaction mechanism with pure NPLs, such as polyethylene terephthalate (PET), aliphatic polyamide (PA), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), and polystyrene (PS) is evaluated using computational chemistry tools. Our results show that arsenic forms stable monolayers on NPLs through surface adsorption, with adsorption energies of 9-24 kcal/mol comparable to those on minerals and composite materials. NPLs exhibit varying affinity towards arsenic based on their composition, with As(V) adsorption showing higher stability than As(III). The adsorption mechanism results from a balance between electrostatics and dispersion forces (physisorption), with an average combined contribution of 87%. PA, PET, PVC, and PS maximize the electrostatic effects over dispersion forces, while PE and PP maximize the dispersion forces over electrostatic effects. The electrostatic contribution is attributed to hydrogen bonding and the activation of terminal O-C, C-H, and C-Cl groups of NPLs, resulting in several pairwise interactions with arsenic. Moreover, NPLs polarity enables high mobility in aqueous environments and fast mass transfer. Upon adsorption, As(III) keeps the NPLs polarity, while As(V) limits subsequent uptake but ensures high mobility in water. The solvation process is destabilizing, and the higher the NPL polarity, the higher the solvation energy penalty. Finally, the mechanistic understanding explains how temperature, pressure, pH, salinity, and aging affect arsenic adsorption. This study provides reliable quantitative data for sorption and kinetic experiments on plastic pollution and enhances our understanding of interactions between water contaminants.


Asunto(s)
Arsénico , Arsenicales , Contaminantes Químicos del Agua , Microplásticos/química , Agua , Arsénico/química , Poliestirenos/química , Polipropilenos/química , Polietileno/química , Tereftalatos Polietilenos , Adsorción , Nylons , Plásticos/química , Contaminantes Químicos del Agua/análisis
18.
Artículo en Inglés | MEDLINE | ID: mdl-38640460

RESUMEN

A ß-cyclodextrin (ß-CD) nanosponge (NS) was synthesized using diphenyl carbonate (DPC) as a cross-linker to encapsulate the antitumor drug cyclophosphamide (CYC), thus obtaining the NSs-CYC system. The formulation was then associated with magnetite nanoparticles (MNPs) to develop the MNPs-NSs-CYC ternary system. The formulations mentioned above were characterized to confirm the deposition of the MNPs onto the organic matrix and that the superparamagnetic nature of the MNPs was preserved upon association. The association of the MNPs with the NSs-drug complex was confirmed through field emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, dynamic light scattering, ζ-potential, atomic absorption spectroscopy, X-ray powder diffraction, selected area electron diffraction, and vibrating-sample magnetometer. The superparamagnetic properties of the ternary system allowed the release of CYC by utilizing magnetic hyperthermia upon the exposure of an alternating magnetic field (AMF). The drug release experiments were carried out at different frequencies and intensities of the magnetic field, complying with the "Atkinson-Brezovich criterion". The assays in AMF showed the feasibility of release by controlling hyperthermia of the drug, finding that the most efficient conditions were F = 280 kHz, H = 15 mT, and a concentration of MNPs of 5 mg/mL. CYC release was temperature-dependent, facilitated by local heat generation through magnetic hyperthermia. This phenomenon was confirmed by DFT calculations. Furthermore, the ternary systems outperformed the formulations without MNPs regarding the amount of released drug. The MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assays demonstrated that including CYC within the magnetic NS cavities reduced the effects on mitochondrial activity compared to those observed with the free drug. Finally, the magnetic hyperthermia assays showed that the tertiary system allows the generation of apoptosis in HeLa cells, demonstrating that the MNPs embedded maintain their properties to generate hyperthermia. These results suggest that using NSs associated with MNPs could be a potential tool for a controlled drug delivery in tumor therapy since the materials are efficient and potentially nontoxic.

19.
Environ Pollut ; 318: 120860, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36521720

RESUMEN

Polyethylene terephthalate (PET) microplastics and nanoplastics are ubiquitously present in the atmosphere as atmospheric and airborne forms (PET-aMPs). Using first-principles calculations, we analyze the uptake of primary air pollutants onto PET-aMPs, focusing on their stabilities, adsorption mechanisms, and thermochemistry. The results show that PET-aMPs are selective for the spontaneous adsorption of CO, CO2, NO, N2O, NO2, NH3, and SO2, reaching stable adsorption energies of 6-20 kcal/mol per molecule, with comparable uptake ability than carbon-based materials, metals/metalloids, and metal oxide surfaces. Then, PET-aMPs become a vector for coexisting air pollutants in the atmosphere, which adsorb by inner or outer adsorption depending on the molecular polarity (dipole moment) and atomic constitution (electronegativity) of gaseous molecules. Also, atmospheric H2O and O2 are not competitive molecules, and ozone could enhance adsorption due to surface oxidation and structure breakdown. The interplay of electrostatic (46-61%) and dispersion forces (21-58%) drives the adsorption mechanism, where low-polar pollutants display almost a balanced electrostatic vs. dispersion contribution, while high polar molecules display a higher electrostatic stabilization. The outer adsorption is reached by strong dispersion, hydrogen bonding, and dipole-dipole-induced pairs, while lone-pair-π interactions appear in the inner adsorption regime. These results expand the understanding of the hazards and risks of atmospheric and airborne microplastics/nanoplastics, their impacts, co-transport ability, and interaction with the environment.


Asunto(s)
Contaminantes Atmosféricos , Contaminantes Químicos del Agua , Microplásticos/química , Plásticos/química , Tereftalatos Polietilenos , Modelos Teóricos , Adsorción , Contaminantes Químicos del Agua/análisis , Polietileno
20.
Sci Total Environ ; 891: 164470, 2023 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-37236484

RESUMEN

Urban wastewaters comprise different hydrophobic pollutants such as microplastics (MPs), pharmaceuticals, and personal care products. Among these pollutants, triclosan (TCS) shows a worrying interaction ability with MPs; recent studies show MPs serve as a vector between TCS and aquatic environments, whose interaction is still being studied to understand their combined toxicity and transport ability. Using computational chemistry tools, this work evaluates the TCS-MPs interaction mechanism, including pristine polymers, i.e., aliphatic polyamides (PA), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). Our results show that TCS adsorption on MPs solely occurs via physisorption, where PA reaches the higher adsorption ability. Remarkably, MPs reach higher or comparable adsorption stability than carbon-based materials, boron nitrides, and minerals, indicating their worrying transport properties. Also, the adsorption capacity is strongly influenced by entropy changes rather than thermal effects, which determine the different sorption capacities among polymers and agree well with reported sorption capacities from adsorption kinetic experiments in the literature. MPs show a polar and highly susceptible surface to establish electrostatics and dispersion effects on TCS. Accordingly, the TCS-MPs interaction mechanism arises from the interplay between electrostatics and dispersion forces, with a combined contribution of 81-93 %. Specifically, PA and PET maximize the electrostatic effects, while PE, PP, PVC, and PS maximize the dispersion effects. From the chemical viewpoint, TCS-MPs complexes interact by a series of pairwise interactions such as Van der Waals, hydrogen bonding, C-H⋯π, C-H⋯C-H, C-Cl⋯C-H, and C-Cl⋯Cl-C. Finally, the mechanistic information explains the effects of temperature, pressure, aging, pH, and salinity on TCS adsorption. This study quantitatively elucidates the interaction mechanism of TCS-MP systems, which were hard to quantify to date, and explains the TCS-MPs sorption performance for sorption/kinetic studies.

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