565 research outputs found
Resolution of 1-n-Butyl-3-Methyl-3-Phospholene 1-Oxide with TADDOL Derivatives and Calcium Salts of O,O’-Dibenzoyl-(2R,3R)- or O,O’-di-p-Toluoyl-(2R,3R)-tartaric Acid
The resolution methods applying (−)-(4R,5R)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane (“TADDOL”), (−)-(2R,3R)-α,α,α',α'-tetraphenyl-1,4-dioxaspiro[4.5]decan-2,3-dimethanol (“spiro-TADDOL”), as well as the acidic and neutral Ca2+ salts of (−)-O,O’-dibenzoyl- and (−)-O,O’-di-p-toluoyl-(2R,3R)-tartaric acid were extended for the preparation of 1-n-butyl-3-methyl-3-phospholene 1-oxide in optically active form. In one case, the intermediate diastereomeric complex could be identified by single crystal X-ray analysis. The absolute P-configuration of the enantiomers of the phospholene oxide was also determined by comparing the experimentally obtained and calculated CD spectra
Gallate semiquinone radical tri-anion:Experimental and theoretical studies of the <sup>13</sup>C hyperfine coupling constants
Probing the interactions of phenol with oxygenated functional groups on curved fullerene-like sheets in activated carbon
The mechanism(s) of interactions of phenol with oxygenated functional groups (OH, COO and COOH) in nanopores of activated carbon (AC) is a contentious issue among researchers. This mechanism is of particular interest because a better understanding of the role of such groups in nanopores would essentially translate to advances in AC production and use, especially in regard to the treatment of organic-based wastewaters. We therefore attempt to shed more light on the subject by employing density functional theory (DFT) calculations in which fullerene-like models integrating convex or concave structure, which simulate the eclectic porous structures on AC surface, are adopted. TEM analysis, EDS mapping and Boehm titration are also conducted on actual phenol-adsorbed AC. Our results suggest the widely-reported phenomenon of decreased phenol uptake on AC due to increased concentration of oxygenated functional groups is possibly attributed to the increased presence of the latter on the convex side of the curved carbon sheets. Such a system effectively inhibits phenol from getting direct contact with the carbon sheet, thus constraining any available π–π interaction, while the effect of groups acting on the concave part of the curved sheet does not impart the same detriment
Bidimensional spectroelectrochemistry: application of a new device in the study of a o-vanillin-copper(II) complex
A new bidimensional spectroelectrochemistry setup for UV-Vis absorption measurements has been developed. The new device has been used to follow electrochemical reactions using two different arrangements: 1) a near-normal configuration that supplies information about the processes taking place both on the electrode surface and in the solution adjacent to it, and 2) a long-optical-pathway configuration based on a mobile slit that controls the position of a light beam passing parallel and adjacent to the electrode surface providing information only about the processes taking place in solution during the electrochemical reaction. The new setup has been validated using o-tolidine, a typical reference system for spectroelectrochemistry. The electrochemical mechanism of oxidation/reduction of Cu(o-Va)2(H2O)2 complex (o-Va = o-Vanillin = 2-hydroxy-3-methoxybenzaldehyde) has been studied using bidimensional UV-Vis absorption spectroelectrochemistry. This Cu(II) complex exhibits antimutagenic, anticarcinogenic and superoxide dismutase mimic properties.Junta de Castilla y León (BU033U16), and Ministerio de Economía y Competitividad (CTQ2014-55583-R, CTQ2014-61914-EXP, CTQ2015-71955-REDT)CONICET, UNLP, Junta de Castilla y León (BU033U16), and Ministerio de Economía y Competitividad (CTQ2014-55583-R, CTQ2014-61914-EXP, CTQ2015-71955-REDT
Rationalization of the mechanism of in situ Pd(0) formation for cross-coupling reactions from novel unsymmetrical pincer palladacycles using DFT calculations
Density functional theory (DFT) is used to determine the mechanism for Pd(0) generation from pincer palladacycle pre-catalysts. The elucidated mechanisms comprise two key steps, transmetallation and reductive elimination. It is found that the presence of a base in the pre-catalyst activation step serves to significantly lower the Gibbs free energy barrier of the transmetallation step and the Gibbs free energy of the overall pre-catalyst activation. The DFT results are used to rationalize the catalytic activity of a number of pincer palladacycles in the Suzuki-Miyaura coupling of sterically demanding and electronically deactivated aryl bromides with 2-tolyboronic acid. A strong correlation exists between the Gibbs free energy barrier of the transmetallation step and/or overall pre-catalyst activation energy and the percentage conversions of the Suzuki- Miyaura coupling in the presence of the novel pre-catalysts. The data presented suggest that the slow, controlled release of the “true, active catalyst,” Pd(0), from the pincer palladacycle pre-catalysts provides the optimum reaction conditions and may be achieved by a high transmetallation energy barrier or overall pre-catalyst activation energy or both
The aqueous Raman optical activity spectra of 4(R)-hydroxyproline: theory and experiment
A DFT study of 2-aminopurine-containing dinucleotides: prediction of stacked conformations with B-DNA structure
Formation of chlorinated breakdown products during degradation of sunscreen agent, 2-ethylhexyl-4-methoxycinnamate in the presence of sodium hypochlorite
Can biotechnology contribute to the development of research and innovation smart specialization strategy (RIS3) in Central and East European countries? Reminiscences from the European Workshop
The paper presents main results and recommendations of the recent European Workshop dedicated to the evaluation of current state and prospects for Biotechnology with the attention to Central and European countries. The contribution of Biotechnology to the RIS3 strategy is also briefly presented. It is believed that there is still insufficient integration of research and innovation, especially in Central and Eastern European countries. Another problem is the weak interest and lack of mechanisms for the entry of potential investors into biotechnology capital–intensive areas. Series of proposals and recommendations coming from the Workshop on how to increase the regional cooperation in the field of Biotechnology is briefly described together with the potential role of international institutions (JRC-EC, CEI, ICGEB, EBTNA) in such cooperation
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