Sol Milena Mejía

Dimercaprol (British antilewisite, BAL) is a long-established chelating agent used in the treatment of heavy metal poisoning; however, its physicochemical and thermochemical properties have not yet been fully characterized. In this study, we combined gas-phase quantum chemical calculations with high-resolution mass spectrometry to investigate the conformational stability, fragmentation pathways, and thermochemical parameters of BAL. Fragmentation behavior was examined by gas chromatography/mass spectrometry-QTOF under electronic ionization conditions, and the resulting spectra were interpreted through proposed dissociation pathways involving water, hydrogen sulfide, and thiyl radical losses, supported by reaction enthalpies calculated at the theoretical level M06-2X/6–311++G( 3df,3pd ). Conformational analysis identified five low-energy structures (BAL-1 to BAL-5), where intramolecular hydrogen bonds and gauche/anti interactions play a key role in stability; BAL-3 was consistently predicted as the lowest-energy conformer. Vibrational frequencies calculated with the B3LYP, M06-2X, and MN15 functionals showed good agreement with experimental FTIR and Raman data. The thermochemical properties were further evaluated using G n composite methods (G3MP2B3, G3B3, G4MP2 and G4) which yielded an average standard enthalpy of formation at ΔH° _{( f,298K )} of –45.6 ± 1.1 kcal/mol. This work provides a detailed experimental and theoretical characterization of dimercaprol, providing information on its possible fragmentation mechanism and conformational landscape, and offering a thermochemical framework that could support future pharmacological, toxicological and environmental applications.

Ionic liquids (ILs) are a promising alternative for CO ₂ capture, offering high stability, environmental friendliness, and scalability. The present theoretical study focused on the evaluation of 12 ILs for the capture of up to 5 CO ₂ molecules. The 12 ILs are based on imidazole and fluorine, [C ₈ H ₄ F ₁₃ mim] ⁺ [BF ₄ ] ⁻ , [C ₈ H ₄ F ₁₃ mim] ⁺ [TFO] ⁻ , [Dmim] ⁺ [BF ₄ ] ⁻ , [Dmim] ⁺ [TFO] ⁻ , [Hmim] ⁺ [FAP] ⁻ , [Dbim] ⁺ [FAP] ⁻ , [Hmim] ⁺ [methide] ⁻ , [Dbim] ⁺ [methide] ⁻ , [Hmim] ⁺ [(PFOc)SO ₃ ] ⁻ , [Omim] ⁺ [(PFOc)SO ₃ ] ⁻ , [Hmim] ⁺ [(PFBu)SO ₃ ] ⁻ , and [Omim] ⁺ [(PFBu)SO ₃ ] ⁻ . A stochastic dynamic search algorithm was used to generate the structure of the nCO ₂ -IL clusters, with n = 1 to 5. The molecular clusters were then optimized using Density Functional Theory (DFT) calculations to describe the nature of the interactions between the 12 ILs and CO ₂ . Results show that CO ₂ physisorps and preferentially interacts with anions, also fluorine substitution increasing CO ₂ affinity. Cluster formation is exothermic and favored at lower temperatures. The physisorption is driven by weak van der Waals interactions. The [Dbim] ⁺ [FAP] ^- , [C ₈ H ₄ F ₁₃ mim] ⁺ [BF ₄ ] ⁻ and [C ₈ H ₄ F ₁₃ mim] ⁺ [TFO] ⁻ ILs demonstrated the highest CO ₂ binding capacity but at the simulated conditions the process is not spontaneous. These findings are useful for designing efficient CO ₂ capture materials based on ILs.

Se hizo una revisión bibliográfica con el objetivo de describir las características y efectos que causan los microplásticos (MP) en la biota marina y el ser humano. Se tuvieron en cuenta artículos científicos publicados sobre el tema entre los años 2010 a 2023. Una vez recopilados, se procedió a eliminar duplicados y a filtrar los artículos restantes con base en criterios de inclusión y exclusión. La revisión de los artículos permitió concluir que, en la caracterización de estos materiales, se evidencia la falta de métodos estandarizados, sin embargo, predominan las técnicas ópticas, espectroscópicas y de pirólisis. Entre las consecuencias para la salud de los ecosistemas y la humana se encuentran, la reducción en la energía metabólica, los cambios morfológicos, el estrés oxidativo, la reducción de la población, los problemas intestinales, etc. Se destacan las diversas opciones que ofrece la industria para aliviar el problema, como las siguientes: filtración, biodegradación, productos sustitutos, etc., pero se hace énfasis en que la principal medida debe ser la reducción en la producción.

In this work, we conducted a study of 7‐exo‐trig cyclizations mechanism involving aryl, vinyl, and alkyl radicals on oxime ethers. Initially, the reaction of brominated oxime ether 9 a with (TMS)₃SiH and AIBN gave rise to aryl radicals that underwent a 7‐exo‐trig cyclization on the oxime ether, yielding dibenzoxepine 10 a, and the ipso reaction and reduction products were obtained as well. Approximate rate constants at 80 °C for the 7‐exo‐trig (1.0×10⁸ s⁻¹) and the ipso cyclization (4.3×10⁷ s⁻¹) were determined by competition experiments. DFT calculations showed good agreement with the experimental results. The reduction rate constant of the N‐alkoxyaminyl radical with (TMS)₃SiH was calculated to be 4.1×10⁻¹ M⁻¹ s⁻¹; while the rate constants for the 7‐exo‐trig cyclizations of vinyl and alkyl radicals on the oxime ether were estimated in the ranges of 10⁶ s⁻¹–10⁸ s⁻¹ and 10³ s⁻¹–10⁸ s⁻¹, respectively. The 7‐exo‐trig cyclization reactions involving aryl, vinyl, and alkyl radicals with oxime ethers were found to be an exothermic and irreversible process, with the oximic carbon showing a preference for nucleophilic alkyl radicals. This kinetic study contributes to the deeper understanding of radical‐mediated cyclizations, enabling the efficient design of complex synthetic routes.

Casearvestrin A, B, and C secundary metabolites, with a promising anticancer potential, were computationally characterized to reveal susceptible sites to nucleophilic and electrophilic attacks, establishing the types and strength of chemical bonds and non-covalent interactions using the B3LYP/6-311++G(d,p) theory level. The chemical behavior prediction was performed by the analysis of local besides global reactivity indexes based on the analysis of the Fukui functions and the topological analysis of the electronic density according to Bader’s theory. Casearvestrin A is the most reactive molecule since it has less hardness, smallest band gap, a highest number of C-H--O weak interactions, and both type of susceptible sites, nucleophilic and electrophilic. Electrophilic attacks are most favored at oxygen atoms of the carbonyl groups, the hydroxyl group, and the cyclic ether. The length of the R chain, which differentiates this type of metabolites, is related to the number of H--H interactions, which in turn has a relationship with the dipole moment

Background: Chagas disease is a potentially fatal disease caused by the parasite Trypanosoma cruzi. There is growing scientific interest in finding new and better therapeutic alternatives for this disease’s treatment. Methods: A total of 81 terpene compounds with potential trypanocidal activity were screened and found to have potential T. cruzi cysteine synthase (TcCS) inhibition using molecular docking, molecular dynamics, ADME and PAIN property analyses and in vitro susceptibility assays. Results: Molecular docking analyses revealed energy ranges from −10.5 to −4.9 kcal/mol in the 81 tested compounds, where pentacyclic triterpenes were the best. Six compounds were selected to assess the stability of the TcCS–ligand complexes, of which lupeol acetate (ACLUPE) and α-amyrin (AMIR) exhibited the highest stability during 200 ns of molecular dynamics analysis. Such stability was primarily due to their hydrophobic interactions with the amino acids located in the enzyme’s active site. In addition, ACLUPE and AMIR exhibited lipophilic characteristics, low intestinal absorption and no structural interferences or toxicity. Finally, selective index for ACLUPE was >5.94, with moderate potency in the trypomastigote stage (EC₅₀ = 15.82 ± 3.7 μg/mL). AMIR’s selective index was >9.36 and it was moderately potent in the amastigote stage (IC₅₀ = 9.08 ± 23.85 μg/mL). Conclusions: The present study proposes a rational approach for exploring lupeol acetate and α-amyrin terpene compounds to design new drugs candidates for Chagas disease.

Amphotericin B (AmB) is an antibiotic with a wide spectrum of action and low multidrug resistance, although it exhibits self-aggregation, low specificity, and solubility in aqueous media. An alternative for its oral administration is its encapsulation in polymers modified with bioconjugates. The aim of the present computational research is to determine the affinity between AmB and six bioconjugates to define which one could be more suitable. The CAM-B3LYP-D3/6-31+G(d,p) method was used for all computational calculations. The dimerization enthalpy of the most stable and abundant systems at pH = 7 allows obtaining this affinity order: AmB_1,2-distearoyl-sn-glycerol-3-phosphorylethanolamine (DSPE) > AmB_γ-cyclodextrin > AmB_DSPEc > AmB_retinol > AmB_cholesterol > AmB_dodecanol, where DSPEc is a DSPE analog. Quantum theory of atoms in molecules, the non-covalent interactions index, and natural bond orbital analysis revealed the highest abundance of noncovalent interactions for AmB-DSPE (51), about twice the number of interactions of the other dimers. Depending on the interactions’ strength and abundance of the AmB-DSPE dimer, these are classified as strong: O-H---O (2), N-H---O (3) and weak: C-H---O (25), H---H (18), C-H---C (3). Although the C-H---O hydrogen bond is weak, the number of interactions involved in all dimers cannot be underestimated. Thus, non-covalent interactions drive the stabilization of copolymers, and from our analysis, the most promising candidates for encapsulating are DSPE and γ-cyclodextrin.

En el presente estudio se realizaron cálculos con base en la Teoría del Funcional de la Densidad Electrónica (DFT) con la aproximación B3PW91/LANL2DZ para optimizar los sistemas monometálicos y bimetálicos Au₉, Au₈Pd, Au₈Pt, AuPd₈, AuPt₈, Pd₉ y Pt₉. Los materiales fueron teóricamente evaluados como catalizadores para la oxidación de monóxido de carbono (CO) y se determinó el sistema más favorable para la adsorción de esta molécula. La sustitución de átomos de Pt y Pd por átomos de Au en los nonámeros generó un cambio en la estructura tridimensional del sistema. El análisis de reactividad global mostró que el clúster más reactivo es 𝑃𝑡₉, seguido por 𝐴𝑢𝑃𝑡₈. Los índices de Fukui identificaron los sitios más susceptibles para un ataque nucleofílico de ambos clústeres. La adsorción de CO generó una cascada de oxidación que liberó ~4,5 eV, indicando que la reacción es altamente exotérmica y exergónica. Los clústeres 𝐴𝑢𝑃𝑡₈ y 𝑃𝑡₉ mostraron los valores más bajos de energía de activación de la etapa determinante del mecanismo. En general, la sustitución de un átomo de platino (o paladio) por un átomo de oro no afecta la reactividad de los nonámeros y, por tanto, se infiere que el clúster 𝐴𝑢𝑃𝑡₈ podría ser un catalizador promisorio en la oxidación de CO. In the current study were development calculations based on Density Functional Theory (DFT) with the B3PW91/LANL2DZ approach for optimizing both monometallic and bimetallic systems: Au₉, Au₈Pd, Au₈Pt, AuPd₈, AuPt₈, Pd₉ y Pt₉. Such materials were theoretically tested as catalyst for the oxidation of carbon monoxide (CO) and the most favorable system for its further adsorption was determined. The substitution of Pt and Pd by Au atoms in the nonamers generated a change in the tridimensional structure of the system. The global reactivity analysis showed that the most reactive cluster is Pt₉ and AuPt₈. On the other hand, the Fukui indexes identified the most susceptible sites for a nucleophilic attack of both clusters. The CO adsorption generated an oxidation cascade which liberated 4,5 eV, indicating that the reaction is highly exothermic and exergonic. Both AuPt₈ and Pt₉ showed the lowest values of activation energy in the determining step of the mechanism. In general, the substitution of a Pt (Pd) atom by an Au atom does not affect the reactivity of the nonamers and then it was evident that the AuPd₈ cluster could be a promissory catalyst in the CO oxidation. No presente estudo, cálculos baseados na Teoria do Funcional da Densidade Eletrônica (DFT) com a abordagem B3PW91/LANL2DZ foram realizados para otimizar sistemas monometálicos e bimetálicos Au₉, Au₈Pd, Au₈Pt, AuPd₈, AuPt₈, Pd₉ y Pt₉. Tais materiais foram teoricamente avaliados como catalisadores para a oxidação do monóxido de carbono (CO) e foi determinado o sistema mais favorável para a adsorção desta molécula. A substituição dos átomos de Pt e Pd por átomos de Au nós não-nomes gerou uma mudança na estrutura tridimensional do sistema. A análise de reatividade global mostrou que o cluster mais reativo é 𝑃𝑡₉, seguido por 𝐴𝑢𝑃𝑡₈. Os índices de Fukui identificaram os sítios mais suscetíveis ao ataque nucleofílico de ambos os clusters. A adsorção de CO gerou uma cascata de oxidação que liberou ~4,5 eV, indicando que a reação é altamente exotérmica e exergônica. Os aglomerados 𝐴𝑢𝑃𝑡₈ 𝑦 𝑃𝑡₉ apresentaram os menores valores de energia de ativação do estágio determinante do mecanismo. Em geral, a substituição de um átomo de platina (ou paládio) por um átomo de ouro não afeta a reatividade dos não-nomes e, portanto, infere-se que o aglomerado 𝐴𝑢𝑃𝑡₈ pode ser um catalisador promissor na oxidação do CO.