Search results for "compounds"
showing 10 items of 3372 documents
Eco-friendly cavity-containing iron oxides prepared by mild routes as very efficient catalysts for the total oxidation of VOCs
2018
Iron oxides (FeOx) are non-toxic, non-expensive and environmentally friendly compounds, which makes them good candidates for many industrial applications, among them catalysis. In the present article five catalysts based on FeOx were synthesized by mild routes: hydrothermal in subcritical and supercritical conditions (Fe-HT, Few200, Few450) and solvothermal (Fe-ST1 and Fe-ST2). The catalytic activity of these catalysts was studied for the total oxidation of toluene using very demanding conditions with high space velocities and including water and CO2 in the feed. The samples were characterized by X-ray diffraction (XRD), scanning and high-resolution transmission electron microscopy (SEM and…
Nuevos materiales moleculares de hierro(II) multipropiedad basados en el fenómeno de transición de espín
2017
En esta Tesis Doctoral se presenta la síntesis y caracterización de una serie de materiales multifuncionales de FeII que tienen como denominador común el fenómeno de transición de espín (TS). El objetivo general es investigar sinergias entre la TS y otra propiedad fisicoquímica mediante el estudio de su estructura molecular y sus propiedades magnéticas y calorimétricas, entre otras. En el Capítulo Uno se exponen los conceptos más relevantes del fenómeno TS en el cual los centros TS experimentan una conversión de espín HS↔LS (HS: estado de espín alto, LS: estado de espín bajo) en respuesta a un estímulo externo tal como temperatura, presión, luz o la presencia de analitos. En particular, una…
Charge-Assisted Halogen Bonding in an Ionic Cavity of a Coordination Cage Based on a Copper(I) Iodide Cluster.
2023
The design of molecular containers capable of selective binding of specific guest molecules presents an interesting synthetic challenge in supramolecular chemistry. Here, we report the synthesis and structure of a coordination cage assembled from Cu3I4– clusters and tripodal cationic N-donor ligands. Owing to the localized permanent charges in the ligand core the cage binds iodide anions in specific regions within the cage by ionic interactions. This allows the selective binding of bromomethanes as secondary guest species within cage promoted by halogen bonding, which was confirmed by single crystal X-ray diffraction. peerReviewed
Stereoselective Synthesis of Spiro-Decalin Oxindole Derivatives via Sequential Organocatalytic Michael-Domino Michael/Aldol Reaction.
2022
A highly stereoselective procedure for the synthesis of spiro-polycyclic oxindoles bearing five contiguous stereogenic centers including two tetrasubstituted carbons has been developed. Under sequential organocatalysis performed by a pyrrolidine-based organocatalyst and DBU, a highly atom-economical Michael–domino Michael/aldol reaction sequence was optimized, yielding variously functionalized spiro-decalin oxindoles with excellent stereoselectivity (>99:1 dr, up to 92% ee). peerReviewed
Icosahedral carboranes as scaffolds for congested regioselective polyaryl compounds : the distinct distance tuning of C-C and its antipodal B-B
2019
Four-fold aryl substituted o-carborane derivatives with defined patterns of substitution at the antipodal region of the cluster carbon atoms have been achieved. It is proven that this region is congested but lacks steric hindrance. Also, the two antipodal sites Cc-Cc and B9-B12 are affected very distinctly by electron donor substituents. peerReviewed
Synthetic Approaches to the Lamellarins—A Comprehensive Review
2014
The present review discusses the known synthetic routes to the lamellarin alkaloids published until 2014. It begins with syntheses of the structurally simpler type-II lamellarins and then focuses on the larger class of the 5,6-saturated and -unsaturated type-I lamellarins. The syntheses are grouped by the strategy employed for the assembly of the central pyrrole ring.
Crystal structure of a new spiro-polytetrahydrofuran compound with translational pseudosymmetry: rac-(2S,2′S,5′R)-2-methyl-5′-[(1R,2R,5S,5′R)-1,4,4,5…
2017
The title compound, C22H34O6, is a product of oxidation of squalene with the catalytic system RuO4(cat.)/NaIO4. The asymmetric unit contains two crystallographically independent molecules of very similar geometry approximately related by the non-crystallographic translation vector c/2. As a consequence, the average diffracted intensity in the hkl layers with odd l is systematically lower than in the layers with even l. In one molecule, the lactone ring and part of the adjacent tetrahydrofuran ring are disordered over two orientations with refined occupancy ratio of 0.831 (10):0.169 (10). The crystal structure is mainly governed by van der Waals forces.
Hazardous air pollutants and primary liver cancer in Texas.
2016
The incidence of hepatocellular carcinoma (HCC), the most common primary liver cancer, is increasing in the US and tripled during the past two decades. The reasons for such phenomenon remain poorly understood. Texas is among continental states with the highest incidence of liver cancer with an annual increment of 5.7%. Established risk factors for HCC include Hepatitis B and C (HBV, HCV) viral infection, alcohol, tobacco and suspected risk factors include obesity and diabetes. While distribution of these risk factors in the state of Texas is similar to the national data and homogeneous, the incidence of HCC in this state is exceptionally higher than the national average and appears to be di…
Synthetic approaches towards huperzine A and B
2013
Huperzine A and B are potent acetylcholinesterase inhibitors and promising against Alzheimer's disease. Completed and formal total syntheses of these medically relevant alkaloids are presented and discussed.
Human DNA Telomeres in Presence of Oxidative Lesions: The Crucial Role of Electrostatic Interactions on the Stability of Guanine Quadruplexes
2019
By using all atom molecular dynamics simulations, we studied the behavior of human DNA telomere sequences in guanine quadruplex (G4) conformation and in the presence of oxidative lesions, namely abasic sites. In particular, we evidenced that while removing one guanine base induces a significant alteration and destabilization of the involved leaflet, human telomere oligomers tend, in most cases, to maintain at least a partial quadruplex structure, eventually by replacing the empty site with undamaged guanines of different leaflets. This study shows that (i) the disruption of the quadruplex leaflets induces the release of at least one of the potassium cations embedded in the quadruplex channe…