Adsorption of Acetone onto MgO: Experimental and Theoretical Evidence for the Presence of a Surface Enolate

A new band at 1640 cm ⁻¹ is revealed by diffuse reflectance FT‐IR spectroscopy of acetone adsorbed on a MgO surface (shown schematically). On the grounds of ab initio quantum‐mechanical calculations, this band is assigned to an adsorbed enolate species. This evidence proves the catalytic role of the metal oxide surface in the condensation reaction mechanism.     

One-Pot Multicomponent Synthesis of Methoxybenzo[h]quinoline-3-carbonitrile Derivatives; Anti-Chagas,X-ray,and In Silico ADME/Tox Profiling Studies

Several methoxybenzo[h]quinoline-3-carbonitrile analogs were designed and synthesized in a repositioning approach to developing compounds with anti-prostate cancer and anti-Chagas disease properties. The compounds were synthesized through a sequential multicomponent reaction of aromatic aldehydes, malononitrile, and 1-tetralone in the presence of ammonium acetate and acetic acid (catalytic). The effect of the one-pot method on the generation of the target product has been studied. The compounds were in vitro screened against bloodstream trypomastigotes of T. cruzi (NINOA and INC-5 strains) and were most effective at showing a better activity profile than nifurtimox and benznidazole (reference drugs). A study in silico on absorption, distribution, metabolism, excretion, and toxicity (ADME/Tox) profiling to help describe the molecular properties related to the pharmacokinetic aspects in the human body of these compounds was reported. In addition, X-ray data for the compound 2-Amino-5,6-dihydro-4-(3-hydroxy-4-methoxy-phenyl)-8-methoxybenzo[h]quinoline-3-carbonitrile 6 was being reported. Spectral (IR, NMR, and elemental analyses) data on all final compounds were consistent with the proposed structures.     

Resonant Fragmentation of the Water Cation by Electron Impact: a Wave-Packet Study

We have investigated the dissociation of a resonant state that can be formed in low energy electron scattering from H₂O⁺. We have chosen the second triplet resonance above the state of H₂O⁺ whose autoionization mainly produces H₂O⁺ ( ). We have considered both dissociation of the resonant state itself, dissociative recombination (DR), or the dissociation of the H₂O⁺ cation after autodetachment, dissociative excitation (DE). The time-evolution of a wave packet on the potential energy surfaces of the resonance and cationic states shows, for the initial conditions studied, that the probability for DR is about 38 % while the probability for DE is negligible.     

Stretchable Gas Barrier Achieved with Partially Hydrogen‐Bonded Multilayer Nanocoating

Super gas barrier nanocoatings are recently demonstrated by combining polyelectrolytes and clay nanoplatelets with layer‐by‐layer deposition. These nanobrick wall thin films match or exceed the gas barrier of SiO_x and metallized films, but they are relatively stiff and lose barrier with significant stretching (≥10% strain). In an effort to impart stretchability, hydrogen‐bonding polyglycidol (PGD) layers are added to an electrostatically bonded thin film assembly of polyethylenimine (PEI) and montmorillonite (MMT) clay. The oxygen transmission rate of a 125‐nm thick PEI‐MMT film increases more than 40x after being stretched 10%, while PGD‐PEI‐MMT trilayers of the same thickness maintain its gas barrier. This stretchable trilayer system has an OTR three times lower than the PEI‐MMT bilayer system after stretching. This report marks the first stretchable high gas barrier thin film, which is potentially useful for applications that require pressurized elastomers.

     

Nano-scale metallodendritic complexes in electron-transfer processes and catalysis

Nano-sized metallodendrimers in which the equivalent metal fragments are located at the periphery can be assembled covalently, by H-bonding (supramolecular) or onto dendronized nanoparticles. They can be used as electron-reservoirs, i.e. molecular batteries, redox catalysts and sensors for the recognition of biologically relevant anions. They can also be deposited on metal surfaces or electrodes, which optimizes their use as recoverable sensors.     

Harmonic Gauss maps of submanifolds of arbitrary codimension of the Euclidean space and sphere and some applications

It is proven results about existence and nonexistence of unit normal sections of submanifolds of the Euclidean space and sphere, which associated Gauss maps, are harmonic. Some applications to constant mean curvature hypersurfaces of the sphere and to isoparametric submanifolds are obtained too.     

A Historical Review of the Total Synthesis of Natural Products Developed in Portugal

Total synthesis of natural products is an important discipline of organic chemistry that has enabled the development of new synthetic methods and strategies for the preparation and study of the structure and reactivity of complex naturally occurring products. In this review we summarize the synthetic strategies developed in Portugal by several research groups for the synthesis of bioactive natural products including alkaloids, cyclitols, fatty alcohols, phenylpropanoic acids, γ-butyrolactones, xanthones and nucleosides.