Resumen: En este estudio se evalúan las propiedades ópticas y electroconductoras de los oligómeros derivados del compuesto tiazolo[5,4-d]tiazol constituidos por 4, 6, 8, 10 y 20 unidades, respectivamente, mediante la teoría de los funcionales de la densidad (DFT) y funcionales de la densidad dependiente del tiempo (TD-DFT). Se calculan la brecha de energía prohibida (Eg), la afinidad electrónica (VAE), la energía de ionización (VIP), la dureza química y las propiedades ópticas como el espectro de emisión y osciladores de fuerza. Los espectros de emisión predichos muestran que la emisión del oligómero se registra con una intensidad alta dentro de la región visible correspondiente al verde en el espectro electromagnético. Se concluye que los oligómeros de tiazolo[5,4-d]tiazol son buenos candidatos para ser usados como material de transporte de carga o material emisor en el diseño de diodos orgánicos emisores de luz (OLED), debido a que muestran buenas propiedades de conducción eléctrica y de transporte de carga.

Abstract: This study assesses the optical and electroconductive properties of oligomers derived from the thiazolo[5,4-d]thiazole compound consisting of 4, 6, 8, 10, and 20 units, respectively, by applying the density functional theory (DFT) and the time-dependent density functional theory (TD-DFT). Band gap (Eg), electron affinity (VAE), ionization energy (VIP), chemical hardness, and optical properties such as emission spectrum and force oscillators are calculated. The predicted emission spectra show that the oligomer’s emission is recorded with high intensity within the green visible light region of the electromagnetic spectrum. It is concluded that thiazolo[5,4-d]thiazole oligomers are good candidates as charge transport material and as emitting material when designing organic light-emitting diodes (OLED) since they show appropriate emission properties, electrical conduction, and freight transport.

Resumen: En el presente estudio, los campos de interacción molecular se aplicaron a un conjunto de datos de 36 derivados del compuesto 5-(nitroheteroaril)-1,3,4-tiadiazol con actividad leishmanicida para generar un modelo 3D-QSAR. La significancia estadística del modelo construido 3D-QSAR es conforme a lo reportado en la literatura. La validación externa indica que el modelo 3D-QSAR es robusto y posee capacidad predictiva. Los resultados muestran que este modelo tiene propiedades estéricas (59.80%) y electrostáticas (40.20%) que desempeñan un papel importante en la actividad leishmanicida. El análisis de los mapas de contorno extraídos a partir de los campos de interacción molecular proporciona información sobre la posible modificación estructural de los derivados del compuesto 5-(nitroheteroaril)-1,3,4-tiadiazol. En conclusión, las actividades biológicas calculadas para el conjunto de entrenamiento y de prueba mostraron un alto grado de concordancia con los valores experimentales, lo que sugiere que el modelo 3D-QSAR construido es útil para diseñar nuevos derivados basados en 1,3,4-tiadiazoles con potencialidad leishmanicida.

Abstract: In the present study, molecular interaction fields are applied to a data set of forty 5-(nitroheteroaryl)-1,3,4-thiadiazol derivatives to generate a 3D-QSAR model. The statistical significance of the 3D-QSAR model is built as reported on the literature. External validation indicates that the 3D-QSAR model is robust and that it has predictive capacity. The results show that the model has steric (59.80%) and electrostatic (40.20%) properties that play an important role in leishmanicidal activity. Analyses of contour maps extracted from molecular interaction fields provide insights on the possible structural modifications of 5-(nitroheteroaryl)-1,3,4-thiadiazole derivatives. These modifications can serve to obtain new derivatives to improve their biological activity. In conclusion, the biological activities calculated for training and test sets show a high degree of concordance with experimental values, suggesting that the constructed 3D-QSAR model is useful for designing new 1,3,4-thiadiazoles derivatives with leishmanicidal potential.

Abstract: This research study examined computationally the geometric, electronic, and thermodynamic properties of a group of complexes formed by aluminum(III) and some amino acids present in the βA peptide, which are involved in the development of Alzheimer's disease. Density Functional Theory (DFT) was used for modeling complexes at the level of theory B3LYP/6-31+G(d,p) resulting in five-coordinated (CP) and four-coordinated (CT) compounds. There were aluminum(III) interactions with O and N ligands: phenolate (Ph-O-), carboxylate (COO-), carbonyl (C=O), amino (RN), and imidazole (ImN). The interactions with greater strength were phenolate and imidazole. In conclusion, the thermodynamic analyses of the structures examined showed that the five-coordinated complexes tend to be more stable than the four-coordinated complexes.

Resumen: Se estudiaron computacionalmente las propiedades geométricas, electrónicas y termodinámicas de un grupo de complejos formados por aluminio(III) con algunos aminoácidos (AA) presentes en la región de afinidad por metales del péptido β-amiloide (β-A) (1-16), implicado en la enfermedad de Alzheimer. Para los cálculos computacionales de los complejos, se usó el funcional híbrido B3LYP en conjunto con la base 6-311+G(d,p). Las geometrías obtenidas correspondieron a complejos tetra-coordinados (CT) y penta-coordinados (CP). Se encontraron interacciones de aluminio(III) con los átomos de O y N de los ligandos fenolato (Ph-O-), carboxilato (COO-), carbonilo (C=O), amínicos (RN) e imidazólicos (ImN). De acuerdo con el análisis de orden natural de enlace, las interacciones con mayor fortaleza de enlace fueron las encontradas para los ligandos fenolato e imidazólico. En conclusión, el análisis termodinámico de las estructuras estudiadas mostró que los complejos penta-coordinados tienden a ser más estables que los tetra-coordinados.

Abstract: This research article proposes a systematic path for the generation of compounds that inhibit the Ebola virus through a molecular docking study. Ebola virus anchoring occurs in the Niemann Pick C1 (NPC1) protein, which is responsible for transporting cholesterol in the endosome/lysosome system. Molecules that have been experimentally reported as possible virus inhibitors were used to assess a possible competitive inhibition in these molecular systems. Several molecules with affinity energies were taken by the active sites, which allowed to identifying the pharmacokinetic potential of these molecules. Adsorption, distribution, metabolism, and excretion of these molecules were also examined. In conclusion, the results obtained show the great inhibitory potential of the A, B, I, J, and K molecules on the anchoring of the Ebola virus glycoprotein with the Niemann Pick C1 protein.

Resumen: En el presente artículo, se propone una ruta para la generación de compuestos que inhiban el virus del Ébola mediante un estudio de acoplamiento molecular. El anclaje del virus del Ébola se da en la proteína Niemann Pick C1 (NPC1), la cual se encarga del transporte de colesterol en el sistema endosoma/lisosoma. Se aprovecharon moléculas que han sido reportadas experimentalmente como posibles inhibidores del virus, para evaluar una posible inhibición competitiva en estos sistemas moleculares. Se tomaron varias moléculas con energías de afinidad por los sitios activos, lo que permitió identificar el potencial farmacocinético de estas moléculas. Asimismo, se hicieron estudios de adsorción, distribución, metabolismo, y excreción. Se concluye que los resultados expuestos en este trabajo muestran el gran potencial inhibitorio de las moléculas A, B, I, J y K, del anclaje de la glicoproteína del virus del Ébola con la proteína Niemann Pick C1.

The structures and molecular interactions of (R)nN-CO2 complexes of amines and CO2 in the gas phase were computationally studied by using ab-initio methods and quantum theory of atoms in molecules (QTAIM). The analysis of the electrostatic potential showed that the interaction N∙∙∙C present in this type of aggregates is favored by the potential difference between the N and C atoms. On the other hand, it was observed the interaction energy is being more exergonic in molecular aggregates having highly substituted amino groups and cyclic structure; in addition, the geometric deformation of CO2 and other additional molecular interactions facilitate the process of complexation of this gas. The QTAIM analysis showed that the interaction N∙∙∙C has an electrostatic character and its strength increases with the substitution of the amino group.

In this research we have designed electron donors D-π-A type containing two different π fragments to obtain naphthopyrrole (D-NPR-A) and naphthotiophene (D-NTP-A) derivatives, proposed for the use in organic bulk hetero-junction (BHJ) solar cells (OSCs). These derivatives were characterized by DFT and TD-DFT calculations. For all the electron donors the anchorage fragment was 2-methylenemalononitrile, while the chromophore fragment was spanned between diphenylamine, triphenylamine, thiophene. Properties affecting open-circuit photovoltage (VOC) and short-circuit photocurrent (JSC) from D-π-A type derivatives, such as geometric structure, frontier-molecular orbital energies, exciton driving force energy, natural bond orbital analysis, absorption spectra and light harvesting efficiency. Energy from HOMO and LUMO orbitals was discussed. Theoretical calculations from TD-DFT within Coulumb attenuation method CAM-B3LYP were able to predict excited state properties. The electron donors D-π-A type exhibit photoelectric conversion efficiency above 10%, being the naphthopyrrole derivatives (D-NPR-A) along with the [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) the complexes with higher photoelectric properties, these complexes are proposed as photoactive materials in the construction of organic bulk hetero-junction solar cells.

<p>In order to evaluate a set of electrical and optical properties by using time-dependent density functional theory (TD-DFT), at level of theory B3LYP/6-31G(d), the 4N-substituted [1,2,4]-Triazole (TAZ) oligomers and substituted derivatives were studied using cyano, amino, methyl and fluoro functional groups. Additionally, specific properties were theoretically evaluated, namely electronic and geometrical properties, excitation energies, λ_max, and the HOMO-LUMO orbital of the different oligomers TAZ with repeated units of 4 to 20 rings. These properties were extrapolated to polymer by using a second order polynomial fit. The oligomers studied exhibited a high molecular planarity, favoring electronic delocalization. Thus, an increase of the monomeric units in the different TAZ oligomers and their corresponding substituents led to an improvement in these properties, showing the best results for the cyano group. The findings contribute to the design of charge carrier polymeric materials and photoluminescent devices (OLEDs).</p>

In the present work was studied theoretically the chemical reactivity of gold clusters (Au n; n = 4, 5 y 6) and gold-silver clusters (Au nAg; n = 4, 5 y 6) at B3LYP/LANL2DZ level of theory using global and local reactivity descriptors in order to analyze reactive behavior of these metallic systems. It was found that the size and doped with silver atom, influence the reactivity of the clusters studied. Also was found that the position of the silver atom in the cluster affects reactivity, being high when this is in the edges of the cluster and low when it occupies a central position.

En el presente trabajo se estudió teóricamente la reactividad química de cúmulos de oro (Au n; n = 4, 5 y 6) y cúmulos de oro-plata (Au nAg) al nivel de teoría B3LYP/LANL2DZ, usando descriptores globales y locales de la reactividad con el fin de analizar el comportamiento reactivo de estos sistemas metálicos. Se encontró que el tamaño y la inclusión de un átomo de plata tienen influencia sobre la reactividad de los cúmulos estudiados. También se observó que la posición que ocupa el átomo de plata en el cúmulo afecta la reactividad, siendo alta cuando este se encuentra en los bordes del cúmulo y baja cuando ocupa una posición central.

In this work was studied the adsorption of sunset yellow dye with different type of activated carbon obtained from vegetable waste. The carbons were characterized by infrared spectroscopy, X-ray diffraction and electron microscopy, obtaining typical results for carbonaceous materials. Surface areas of activated carbon were determined by nitrogen isotherms. Similarly, dye removal isotherms were evaluated taking into account, contact time effect, pH, initial concentration and amount of adsorbent. Corn cob carbons, showed highest removal percentage with respect at the carbons of coconut husks and rice husks. Langmuir’s isotherm model is adjusted more appropriately to these results. We found that, pseudo second order kinetics model describes in good agreement the adsorption of sunset yellow dye with activated carbons.

Se estudió la remoción del colorante amarillo anaranjado con diferentes tipos de carbón activado, obtenidos a partir varias fuentes de desechos agrícolas. Los carbones se caracterizaron mediante espectroscopía infrarroja, difracción de rayos X y microscopía electrónica de barrido, obteniéndose resultados típicos de materiales carbonosos. El área superficial del carbón activo, se determinó mediante isotermas de nitrógeno. De igual manera, se evaluó la isoterma de remoción del colorante teniendo en cuenta el efecto del tiempo de contacto, el pH, la concentración inicial y la cantidad de adsorbente. El carbón de tusa de maíz mostró mayor porcentaje remoción de colorante con respecto a los carbones cáscara de coco y cascarilla de arroz. El modelo de isoterma de Langmuir se ajusta de manera más apropiada a estos resultados. Se encontró que el modelo cinético de pseudo segundo orden describe muy bien el proceso de adsorción del colorante amarillo anaranjado con los carbones activados.

Potential energy surface (PES) of cis-trans and trans-trans formic acid dimers were sampled using a stochastic method, and the geometries, energies, and vibrational frequencies were computed at B3LYP/6-311++G(3df,2p) level of theory. The results show that molar free energy of dimerization deviated up to 108.4% when basis set superposition error (BSSE) and zero-point energy (ZPE) were not considered. For cis-trans dimers, C=O and O - H bond weakened, whereas C - O bonds strengthened due to dimerization. Also, trans-trans FA dimers did not show a trend regarding strengthening or weakening of the C=O, O - H and C - O bonds.

Density functional theory was used to investigate the global and local reactivity of some cis-platinum(II) complexes including anticancer drugs, such as cisplatin and carboplatin. Calculated equilibrium geometries at mPW1PW/LANL2DZ* are in close agreement with their available X-ray data. We develop three new local reactivity descriptors: atomic descriptor of philicity, atomic descriptor group and atomic descriptor of philicity group for determining chemical reactivity and selectivity of the studied complexes. This contribution on chemical reactivity allow us to establish qualitative trends, which enable our descriptors for use in rational platinum based anticancer drug design.