Search results for "electron transfer"
showing 10 items of 282 documents
Self-Assembly-Directed Organization of a Fullerene–Bisporphyrin into Supramolecular Giant Donut Structures for Excited-State Charge Stabilization
2021
Functional materials composed of spontaneously self-assembled electron donor and acceptor entities capable of generating long-lived charge-separated states upon photoillumination are in great demand as they are key in building the next generation of light energy harvesting devices. However, creating such well-defined architectures is challenging due to the intricate molecular design, multistep synthesis, and issues associated in demonstrating long-lived electron transfer. In this study, we have accomplished these tasks and report the synthesis of a new fullerene–bis-Zn-porphyrin e-bisadduct by tether-directed functionalization of C60 via a multistep synthetic protocol. Supramolecular oligom…
Electro- and magneto-electrochemistry of zeolite Y- and MCM-41-associated bipyrylium ion
2005
Abstract The electrochemical response of bipyrylium bication [1,4-bis(3,5-diphenyl-4-pyrylium)phenylene] associated with Y and MCM-41 aluminosilicates (BTP@Y and BTP@MCM, respectively) is described using polymer-film electrodes immersed into Et 4 N + + MeCN and Bu 4 N + + MeCN electrolytes. BTP@MCM provides a solution-like response in all electrolytes consisting in two successive strongly comproportionation mediated one-electron reduction processes near to +0.05 and −0.12 V vs. Ag|AgCl. The response of BTP@Y in Bu 4 N + + MeCN is restricted to a unique reduction process near to −0.40 V, while in Et 4 N + + MeCN, it differs significantly: here, two reduction processes at −0.22 and −0.36 …
Electrochemical treatment of aqueous solutions containing one or many organic pollutants at boron doped diamond anodes. Theoretical modeling and expe…
2012
The electrochemical oxidation of organics in water at boron doped diamonds (BDD) was experimentally investigated with the aim to discuss the correlations among the conversion of the pollutants and the instantaneous current efficiency ICE with the operative conditions. A simple theoretical model previously developed for the oxidation of oxalic acid accounting for the cases of mass transfer control, oxidation reaction control and mixed kinetic regimes was adopted and extended to challenge its predictive capability in the case of organics of different nature and in systems with more pollutants. A quite good agreement, between theoretical predictions and experimental data pertaining to the elec…
A DFT investigation of CO oxidation over neutral and cationic gold clusters
2009
Abstract The interaction of CO and O 2 with neutral and positively charged Au 9 and Au 13 clusters was studied using Density Functional Theory. The aim was the understanding of the elementary steps of the low temperature activity of supported gold nanoparticles towards carbon monoxide combustion, that is, the oxidation of CO to CO 2 in presence of dioxygen molecules. The adsorption of a single CO molecule gives rise to a substantial electronic rearrangement on both neutral and cationic gold clusters. On the contrary, the adsorption of dioxygen produces an electron transfer from neutral gold clusters to the O 2 , while the interaction with cationic Au nanoparticles is simply electrostatic. C…
Effects of the herbicides Benzoylpropethyl and flampropisopropyl on rat liver mitochondria : an alteration in membrane fluidity ?
1984
Abstract The action of the herbicides benzoylpropethyl and flampropisopropyl, and the corresponding unesterified acids was studied in rat liver mitochondria. The herbicides were found to (a) inhibit the mitochondrial electron transfer in complex III or at the level of ubiquinone (I50 of 4 nmol mg protein−1 for flampropisopropyl and 18 for benzoylpropethyl with succinate as a substrate); (b) have an additional (however less sensitive) site of inhibition near succinate dehydrogenase; and (c) interfere with energy transfer. Sensitivity was increased 2- (benzoylpropethyl) and 3.5-fold (flampropisopropyl) as the rats age increased from 12–13 weeks to 23–26 weeks. The free acids were far less eff…
Kinetik der energieverbrauchenden Rückreaktion in der Atmungskette
1964
Die Kinetik der energieabhangigen Ruckreaktionen der Atmungskette wird fur die Atmungskettenkomponenten gemessen. Energiezufuhr wird durch Zusatz von ATP ausgelost. Die relative Geschwindigkeit der Ruckreaktion und der untersuchten Reaktionsschritte ist gleich gros (0,30 sec−1) bei 15°. Die Halbsattigungskonstante fur ATP in der Ruckreaktion ist 40 μM. Geschwindigkeitslimitierend fur die Ruckreaktion in der Atmungskette ist die Energieuberfuhrung von ATP. Die Hinreaktionen der Atmungskette, soweit sie zur Phosphorylierung gekoppelt ist, wird ebenfalls durch die Energieuberfuhrung auf ADP limitiert. Hohe Geschwindigkeiten der Hinreaktion lassen sich bei Entkopplung messen. Die Befunde deuten…
Proton-Coupled Electron Transfer in Ferrocenium–Phenolate Radicals
2013
Electron and proton transfer (ET, PT) can be intimately coupled, provided suitable redox and acid/base sites are available. The amide-linked ferrocene–phenol H-1 is deprotonated to the phenolate [1]– by phosphazene bases and oxidized to the ferrocenium ion [H-1]+ by silver hexafluoroantimonate. Concomitant oxidation and deprotonation yields the radical [1]•, featuring a characteristic near-IR absorption band. The ground state of [1]• is best described as the ferrocenium–phenolate zwitterion [1b]• with a dynamic dissymmetric N···H···O hydrogen bond (PT). The ferrocenium–iminolate N···H–O tautomer [1b]•-NHO′ can undergo a thermal structural rearrangement to the high-energy OH···O tautomer [1b…
ChemInform Abstract: Cross-Dehydrogenative Couplings Between Indoles and β-Keto Esters: Ligand-Assisted Ligand Tautomerization and Dehydrogenation vi…
2014
Cross-dehydrogenative coupling reactions between β-ketoesters and electron-rich arenes, such as indoles, proceed with high regiochemical fidelity with a range of β-ketoesters and indoles. The mechanism of the reaction between a prototypical β-ketoester, ethyl 2-oxocyclopentanonecarboxylate, and N-methylindole has been studied experimentally by monitoring the temporal course of the reaction by (1)H NMR, kinetic isotope effect studies, and control experiments. DFT calculations have been carried out using a dispersion-corrected range-separated hybrid functional (ωB97X-D) to explore the basic elementary steps of the catalytic cycle. The experimental results indicate that the reaction proceeds v…
Cross-Dehydrogenative Couplings between Indoles and beta-Keto Esters: Ligand-Assisted Ligand Tautomerization and Dehydrogenation via a Proton-Assiste…
2014
Cross-dehydrogenative coupling reactions between β-ketoesters and electron-rich arenes, such as indoles, proceed with high regiochemical fidelity with a range of β-ketoesters and indoles. The mechanism of the reaction between a prototypical β-ketoester, ethyl 2-oxocyclopentanonecarboxylate, and N-methylindole has been studied experimentally by monitoring the temporal course of the reaction by (1)H NMR, kinetic isotope effect studies, and control experiments. DFT calculations have been carried out using a dispersion-corrected range-separated hybrid functional (ωB97X-D) to explore the basic elementary steps of the catalytic cycle. The experimental results indicate that the reaction proceeds v…
Entropy-controlled diastereoselectivity in the photocyclization of rigid derivatives of o-allylaniline.
2002
Two rigid derivatives of o-allylaniline, namely 8-allyl-2-phenyl-1,2,3,4-tetrahydroquinoline (1b) and 7-(trans-2-cinnamyl)-2-methylindoline (1c), have been chosen as suitable systems to study the potential stereoselectivity of the photocyclization process. Photolysis of 1b leads to a mixture of diastereomeric lilolidines 4 (trans/cis), while 1cproduces a mixture of 4 (trans/cis) and the tetrahydropyrrolo[3,2,1-hi]indole derivatives 5 (trans/cis). To disclose whether the diastereoselectivity could be entropy dependent, photolysis of 1b and 1c has been performed at several temperatures. In both cases, linear relationships have been observed when ln(k(t)/k(c)) (the relative reaction rate const…