Thermal behavior and thermodynamic parameters of some complexes of biologically active nucleic acid constituents

The thermal behavior of some complexes derived from biologically nucleic acid constituents has been studied applying differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Thermodynamic parameters, decompositions and thermal stabilities are calculated and explained. All the complexes gave exothermic peaks with -ve signs for change of entropy values, ΔS which indicate that the activated transition states are more ordered, i.e. in a less random molecular configuration than the reacting complexes. TGA gives the mechanism of decomposition.

Embracing The Phantom Or The Imaginary Show

Hundreds or maybe thousands of ghosts haunt our theatre. When I say ours, I do not want to refer to the Romanian one, but neither to the territory proposed and researched by Monique Borie in her already famous book dedicated to spectres. All my shows, and here we talk about more than seventy performances, now appear like ghosts to me. They were played sometime and constitute, not only for me, but for thousands, or tens of thousands of spectators, memories, true glimpses of moments, sometimes beautiful, sometimes sad, relics that begin to fade into a mnemonic mechanism of decomposition of the sensations once arisen by the scenic action and the image proposed through the presence of the actor. Thus, the spirit places the theatre under the protective wing of the document-memory, remaking, for those who were not in the position of witnesses, the way of late understanding for the one who can only imagine. The Romanian theatre does not have too many moments, perhaps astral, that could elucidate us on a certain artistic approach or against another. Too often the document-memory is activated by chronicles that bear far too many subjective opinions or timid analyzes on the work of a profession that deserves more in this regard. A very important director of the end of the last century, a student of Professor Radu Penciulescu, defined his own phantasma through the imaginary shows he left us. Blessed is he. Aureliu Manea’s writing allows us to imagine more than the chronicles of his shows played on Romanian stages could do. The document-memory of these documents concerns me and holds me in an embrace that I feel violently present.

Electron impact dissociation of CO2 (a review)

Based on a detailed analysis and generalization of the results of calculations of the energy spectrum of electrons using different models in gas discharges in pure carbon dioxide CO2 and in mixtures containing CO2 , the rate constant of CO2 dissociation by electron impact in a gas discharge of direct current at atmospheric pressure is found. It is shown that, at values of the reduced electric field from 55 Td to 100 Td, the predominant mechanism of decomposition of the CO2 molecule is the collision of CO2 molecules with electrons. An expression is obtained for calculating the rate constant of CO2 dissociation by electron impact as a function of the reduced electric field.

Decomposition of Ruthenium Olefin Metathesis Catalyst

Ruthenium olefin metathesis catalysts are one of the most commonly used class of catalysts. There are multiple reviews on their uses in various branches of chemistry and other sciences but a detailed review of their decomposition is missing, despite a large number of recent and important advances in this field. In particular, in the last five years several new mechanism of decomposition, both olefin-driven as well as induced by external agents, have been suggested and used to explain differences in the decomposition rates and the metathesis activities of both standard, N-heterocyclic carbene-based systems and the recently developed cyclic alkyl amino carbene-containing complexes. Here we present a review which explores the last 30 years of the decomposition studied on ruthenium olefin metathesis catalyst driven by both intrinsic features of such catalysts as well as external chemicals.

Poison or Promoter? Investigating the Dual-Role of Carbon Monoxide in Pincer-Iridium-Based Alkane Dehydrogenation Systems via Operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy

<p>Pincer-ligated iridium complexes of the <a>form [Ir(^R4PCP)L] (^R4PCP = κ³-C₆H₃-2,6-(XPR₂)₂; X = CH₂, O; R = <i>t</i>Bu, <i>i</i>Pr) </a>have previously been shown competent for acceptorless alkane dehydrogenation when supported on silica. It was observed by post-catalysis solid-state NMR that silica-tethered <a>[Ir(C₂H₄)(≡SiO-<i>^t</i>^Bu4POCOP)] </a>(<b>3-C₂H₄</b>) was converted fully to [Ir(CO)(≡SiO-<i>^t</i>^Bu4POCOP)] (<b>3-CO</b>) at 300 °C. In this work, the characterization of species under dehydrogenation reaction conditions far from equilibrium between butane and butenes (approach to equilibrium <i>Q</i>/<i>K</i>_eq = 0.3 at 300 °C) is performed with <i>operando </i>Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS) to show the kinetics of species conversion from <b>3-C₂H₄</b> to <b>3-CO</b>. It is further found that [IrClH(≡SiO-<i>^t</i>^Bu4POCOP)] (<b>3-HCl</b>), a species considered to be a precatalyst for alkane dehydrogenation, is also fully converted to <b>3-CO</b>. A mechanism of decomposition is proposed that implicates surface silanol groups, while carbon monoxide acts as a “stabilizer” for the catalyst by promoting their reductive elimination and maintaining the complex in the I oxidation state. </p>

Poison or Promoter? Investigating the Dual-Role of Carbon Monoxide in Pincer-Iridium-Based Alkane Dehydrogenation Systems via Operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy

<p>Pincer-ligated iridium complexes of the <a>form [Ir(^R4PCP)L] (^R4PCP = κ³-C₆H₃-2,6-(XPR₂)₂; X = CH₂, O; R = <i>t</i>Bu, <i>i</i>Pr) </a>have previously been shown competent for acceptorless alkane dehydrogenation when supported on silica. It was observed by post-catalysis solid-state NMR that silica-tethered <a>[Ir(C₂H₄)(≡SiO-<i>^t</i>^Bu4POCOP)] </a>(<b>3-C₂H₄</b>) was converted fully to [Ir(CO)(≡SiO-<i>^t</i>^Bu4POCOP)] (<b>3-CO</b>) at 300 °C. In this work, the characterization of species under dehydrogenation reaction conditions far from equilibrium between butane and butenes (approach to equilibrium <i>Q</i>/<i>K</i>_eq = 0.3 at 300 °C) is performed with <i>operando </i>Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS) to show the kinetics of species conversion from <b>3-C₂H₄</b> to <b>3-CO</b>. It is further found that [IrClH(≡SiO-<i>^t</i>^Bu4POCOP)] (<b>3-HCl</b>), a species considered to be a precatalyst for alkane dehydrogenation, is also fully converted to <b>3-CO</b>. A mechanism of decomposition is proposed that implicates surface silanol groups, while carbon monoxide acts as a “stabilizer” for the catalyst by promoting their reductive elimination and maintaining the complex in the I oxidation state. </p>

Poison or Promoter? Investigating the Dual-Role of Carbon Monoxide in Pincer-Iridium-Based Alkane Dehydrogenation Systems via Operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy

<p>Pincer-ligated iridium complexes of the <a>form [Ir(^R4PCP)L] (^R4PCP = κ³-C₆H₃-2,6-(XPR₂)₂; X = CH₂, O; R = <i>t</i>Bu, <i>i</i>Pr) </a>have previously been shown competent for acceptorless alkane dehydrogenation when supported on silica. It was observed by post-catalysis solid-state NMR that silica-tethered <a>[Ir(C₂H₄)(≡SiO-<i>^t</i>^Bu4POCOP)] </a>(<b>3-C₂H₄</b>) was converted fully to [Ir(CO)(≡SiO-<i>^t</i>^Bu4POCOP)] (<b>3-CO</b>) at 300 °C. In this work, the characterization of species under dehydrogenation reaction conditions far from equilibrium between butane and butenes (approach to equilibrium <i>Q</i>/<i>K</i>_eq = 0.3 at 300 °C) is performed with <i>operando </i>Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS) to show the kinetics of species conversion from <b>3-C₂H₄</b> to <b>3-CO</b>. It is further found that [IrClH(≡SiO-<i>^t</i>^Bu4POCOP)] (<b>3-HCl</b>), a species considered to be a precatalyst for alkane dehydrogenation, is also fully converted to <b>3-CO</b>. A mechanism of decomposition is proposed that implicates surface silanol groups, while carbon monoxide acts as a “stabilizer” for the catalyst by promoting their reductive elimination and maintaining the complex in the I oxidation state. </p>