Here, we analyze the possibility of predicting local and global current densities in a series bicyclic hydrocarbons with 4n + 2 π-electrons from nucleus-independent chemical shifts (NICS) computations.

Recently, we reported a series of global minima whose structures consist carbon rings decorated with heavier group 14 elements. Interestingly, these feature planar tetracoordinate carbons (ptCs) and result from the replacement five or six protons (H+) cyclopentadienyl anion (C5H5−) pentalene dianion (C8H62−) by three four E2+ dications (E = Si–Pb), respectively. The silicon derivatives are Si3C5 Si4C8 clusters. Here show that ptC persists in some clusters an equivalent number C Si atoms,...

Despite the central role of aromaticity in chemistry expanded porphyrins, evaluation remains difficult for these extended macrocycles. The presence multiple conjugation pathways and different planar nonplanar π-conjugation topologies makes quantification global local even more challenging. In neutral predominance aromatic pathway passing through imine-type nitrogens circumventing amino NH groups is established. However, charged macrocycles, question about main circuit open. Accordingly, a...

Abstract Extensive explorations of their potential energy surfaces, combined with high‐level quantum chemical computations, strikingly show that the lowest structures (Li 6 Si 5 ) 2–5 systems consist 6− aromatic units, surrounded by Li + counterions, respectively. These viable gas‐phase compounds are pioneering reported cases oligomers made planar silicon rings. Based on key evidence these energetically favored, and rings aromaticity is thoroughly preserved, cluster proposed as a assembly...

The minimum energy structures of the Si3C5 and Si4C8 clusters are planar contain tetracoordinate carbons (ptCs). These species have been classified, qualitatively, as global (π) local (σ) aromatics according to adaptive natural density partitioning (AdNDP) method, which is an orbital localization method. This work evaluates these species’ aromaticity, focusing on confirming quantifying their aromatic character. For this purpose, we use method based molecular space topology electronic...

The aromaticity and dynamics of a set recently proposed neutral 5- 6-membered heterocycles that are closed by dative (donor-acceptor) or multi-center σ bonds, have resonance forms with Hückel number π-electrons, examined. donors acceptors in the rings include N, O, F, B, Be, Mg, respectively. planar geometry rings, coupled evidence from different measures aromaticity, namely NICSzz, NICSπzz components conventional nucleus independent chemical shifts (NICS), ring current strengths (RCS),...

Abstract Here we show that substituting the ten protons in dianion of a bispentalene derivative (C 18 H 10 2− ) by six Si 2+ dications produces minimum energy structure with two planar tetracoordinate carbons (ptC). In 6 C , ptCs are embedded terminal 5 pentagonal rings and participate three‐center, two‐electron (3c‐2e) Si‐ptC‐Si σ‐bond. Our exploration potential surface identifies triphenylene as putative global minimum. Nevertheless, robustness to Born–Oppenheimer molecular dynamics (BOMD)...

Xenobiotic reductase B (XenB) catalyzes the reduction of aromatic ring or nitro groups nitroaromatic compounds with methyl, amino hydroxyl radicals. This reaction is biotechnological interest for bioremediation, reuse industrial waste activation prodrugs. However, structural factors that explain binding XenB to different substrates are unknown. Molecular dynamics simulations and quantum mechanical calculations were performed identify residues involved in formation stabilization...

Se ha estudiado la influencia del pH y cinética de biosorción plomo a 20°C en el algaAscophyllum nodosum. Para aumentar estabilidad estructural alginato e impedir sulixiviación, biomasa fue pre-tratada con CaCl2. Los datos experimentales debiosorción presentaron mayores coeficientes correlación para modelo matemático depseudo segundo orden. parámetros fisicoquímicos: tamaño partícula(75 μm - 180 0 75 μm), dosis adsorbente concentración metal fueronevaluados biosorción. La constante pseudo...

Here we show that substituting the ten protons in dianion of a bispentalene derivative (CH) by six Si dications produces minimum energy structure with two planar tetracoordinate carbons (ptC). In SiC, ptCs are embedded terminal C pentagonal rings and participate three-center, two-electron (3c-2e) Si-ptC-Si σ-bond. Our exploration potential surface identifies triphenylene as putative global minimum. But robustness to Born-Oppenheimer molecular dynamics (BOMD) simulations at 900 1500 K...

The minimum energy structures of the Si3C5 and Si4C8 clusters are planar contain tetracoordinate carbons (ptCs). These species have been classified, qualitatively, as global () local aromatics according to adaptive natural density partitioning (AdNDP) method, which is an orbital localization method. This work evaluates these species' aromaticity, focusing on confirming quantifying their aromatic character. For this purpose, we use method based molecular space topology electronic function...

Abstract Hot cracking susceptibility and the formation of brittle martensite phase are main factors that limit weldability a dissimilar joint between carbon steel (CS) austenitic stainless (SS). In this study, self-constraint finger test was used to correlate welding thermo-mechanical field with crack weld CS ASTM A36 SS AISI 304L. The allowed intercalate fingers (portions) tested materials in samples produce welds. heat dissipation distortion behavior were related susceptibility, critical...

Se ha estudiado la cinética de biosorción cadmio a 20°C en pectina extraída cáscaras naranja obteniéndose una capacidad adsorción el equilibrio, q ,igual 99,56 mg/g e rango pH 4,5-5,5. El material péctico fue extraído mediante hidrólisis ácida (pH: 1,5, temperatura: 90°C, tiempo: 30 min) y reticulado con formaldehído medio ácido para disminuir su hidratación hinchamiento, así como impedir que se produzca lixiviación del polisacárido al encontrarse acuoso. Los datos experimentales presentaron...

Se ha estudiado la biosorción de plomo en el alga Ascophyllum nodosum a 20°C y unpH inicial 4-5 empleando los modelos isoterma Langmuir Freundlich. Para laestabilización del se empleó CaCl2. La granulometría empleada biosorbente fue0-75 μm. En análisis por espectroscopía infrarrojo con transformada Fourier, FTIR,se observó una pequeña disminución señal torno al grupo carbonilo para lamuestra reticulada antes metal después (1600,92 cm-1 1573,91cm-1) 1400 (que pasó 1415,75 1409,96 cm-1),...

Se ha desarrollado una membrana de líquidos iónicos polimerizados (PILM) a partir la copolimerización del bromuro 3-butil-1-vinilimidazolio y acrilonitrilo, posteriormente cargada con el indicador amarillo brillante (AB) mediante un proceso intercambio iónico (PILM-AB). El objetivo este fue utilización en medición pH soluciones acuosas rango 6,5 8,0; cercano condiciones neutras. Las membranas crudas PILM cargadas PILM-AB fueron caracterizadas FT-IR respuesta las respecto al cambio medida...

The aromaticity of charged expanded porphyrins turns out to be much more complex study than that their planar neutral analogues. In particular, identifying the most conjugated circuit is no longer straightforward. addition planarity, protonation and deprotonation porphyrinoids play an important role in determining aromaticity. We have demonstrated largest do not present a clear main conjugation pathway. Among preferred aromatic indices, AVmin ends up being useful tool for recognizing path....