Search results for "ELECTRON TRANSFER"
showing 10 items of 282 documents
Kinetic evidence for the solubilization of pyridine-2-azo-p-dimethylaniline in alkanediyl-α,ω-bis(dimethylcetylammonium nitrate) surfactants. Role of…
2004
The incorporation of the bidentate ligand pyridine-2-azo-p-dimethylaniline (PADA) into micellar aggregates of the dimeric cationic surfactants propanediyl-, hexanediyl- and dodecanediyl-alpha,omega-bis(dimethylcetylammonium nitrate) (16-3-16,2NO(3)(-), 16-6-16,2NO(3)(-) and 16-12-16,2NO(3)(-), respectively) has been studied at 25 degreesC by examining the kinetics of the complexation reaction of the Ni(II) ion with this ligand. For comparison, cetyltrimethylammonium nitrate ( CTAN), which can be considered as the "monomeric'' surfactant of 16-3-16,2NO(3)(-), has also been used. The kinetic data have shown that, for 16-3-16,2NO(3)(-) and CTAN, at a surfactant concentration below the critical…
One electron transfer chain decomposition of trifluoroacetone diperoxide: The first 1,2,4,5-tetroxane with O-transfer capability
1992
Abstract Reaction of 1,1,1-trifluoropropanone (trifluoroacetone) ( 1a ) with 30% hydrogen peroxide in the presence of conc. sulfuric acid afforded in good yield 3,6-bis(trifluoromethyl)-3,6-dimethyl-1,2,4,5-tetroxane or trifluoroacetone diperoxide ( 2a ). Peroxide 2a is quantitatively converted into trifluoroacetone ( 1a ) and dioxygen by a catalytic amount of tetrabutylammonium iodide through a reductive electron transfer chain reaction carried out by the superoxide ion. Trifluoroacetone diperoxide ( 2a ) is capable of O-atom transfer to alkenes and sulfides.
Magnetoelectrochemical modulation of pre-organization processes in a 4,4′-dinitrobiphenyl azacrown macrocyclic lactam
2004
A magnetoelectrochemical effect consisting on the modulation of the reaction rate of pre-organization reactions in a 4,4′-dinitrobiphenyl azacrown lactam is described. The electrochemical response of that compound in DMSO solution at microelectrodes consists in two successive dinitrobiphenyl-centred one-electron transfer processes at −0.9 and −1.6 V vs. AgCl/Ag involving the transition from the dihedral geometry of the neutral starting compound to the planar geometry of the final dianion, resulting in an overall ECE mechanism. In the presence of moderate (0.05–0.2 T) static magnetic fields, the second electron transfer process decreases significantly, the apparent rate constant of the dihed…
Mechanism of four-electron reduction of dioxygen to water by ferrocene derivatives in the presence of perchloric acid in benzonitrile, catalyzed by c…
2004
The selective two-electron reduction of dioxygen occurs in the case of a monocobalt porphyrin [Co(OEP)], whereas the selective four-electron reduction of dioxygen occurs in the case of a cofacial dicobalt porphyrin [Co(2)(DPX)]. The other cofacial dicobalt porphyrins [Co(2)(DPA), Co(2)(DPB), and Co(2)(DPD)] also catalyze the two-electron reduction of dioxygen, but the four-electron reduction is not as efficient as in the case of Co(2)(DPX). The micro-superoxo species of cofacial dicobalt porphyrins were produced by the reactions of cofacial dicobalt(II) porphyrins with dioxygen in the presence of a bulky base and the subsequent one-electron oxidation of the resulting micro-peroxo species by…
Photoinduced Electron Transfer in Multiporphyrinic Interlocked Structures: The Effect of Copper(I) Coordination in the Central Site
2004
Photoinduced processes have been determined in a [2]catenane containing a zinc(II) porphyrin, a gold(III) porphyrin, and two free phenanthroline binding sites, Zn-Au(+), and in the corresponding copper(I) phenanthroline complex, Zn-Cu(+)-Au(+). In acetonitrile solution Zn-Au(+) is present in two different conformations: an extended one, L, which accounts for 40 % of the total, and a compact one, S. In the L conformation, the electron transfer from the excited state of the Zn porphyrin to the gold-porphyrin unit (k = 1.3x10(9) s(-1)) is followed by a slow recombination (k = 8.3x10(7) s(-1)) to the ground state. The processes in the S conformation cannot be clearly resolved but a charge-separ…
DNA Oxidation Photoinduced by Norharmane Rhenium(I) Polypyridyl Complexes: Effect of the Bidentate N,N′-Ligands on the Damage Profile
2018
Re(I)--polypyridyl complexes have interesting and distinctive photochemical and photosensitizing properties. This work describes the capability to induce (or photoinduce) DNA damage of three Re(I)-complexes with a naturally occurring alkaloid called norharmane (nHo) as ligand: [Re(CO)₃ (nHo)(L)]CF₃ SO₃ where L=2,2'-bipyridine (ReBpy), phenanthroline (RePhen) or dipyrido[3,2-a:2',3'-c]phenazine (ReDppz). The interaction of the complexes with DNA was investigated by steady-state and time-resolved spectroscopy. Data show that the mode and strength of interaction depend on the chemical structure of the bidentate ligand. The complexes show a major static contribution to the overall interaction, …
Logic gates scheme based on Coulomb blockade in metallic nanoclusters with organic ligands
2010
We propose a logic gates scheme based on the electron transfer through metallic nanoclusters linked to organic ligands and discuss theoretically the characteristics needed for practical implementation. As a proof-of-the-concept, we demonstrate the OR, AND and NOT gates and study the performance in terms of temperature, applied voltage, and noise.
Unprecedented reactivity of a Schiff base ligand in the co-ordination sphere of copper(I) complex towards β-diketones. Synthesis and X-ray characteri…
2002
International audience; The reactions of the copper(I) derivative [CuL(THF)(CH3CN)]PF6 (1), in which L is the di-imine/pyridine ligand 2,6-bis[1-(2,6-diisopropylphenylimino)ethyl]pyridine, with different β-diketones (2,4-pentanedione (acacH), 1,3-diphenyl-1,3-propanedione (dbm)) yielded the new Cu(I) salt [CuL′2]PF6 (2) (L′: 2-[acetyl]-6-[1-(2,6-diisopropylphenylimino)ethyl]pyridine). These reactions of β-diketones with a di-imine/pyridine ligand co-ordinated to a Cu(I) centre constitute the first example of a partial hydrolysis of such a Schiff base within the inner sphere of a Cu centre. Compound 2·acaH has been characterised by X-ray crystallography. © 2002 Elsevier Science B.V. All righ…
Base Control of Electron-Transfer Reactions of Manganese(III) Porphyrins
2000
Homogeneous electron-transfer kinetics for the reduction of four different manganese(III) porphyrins using different reductants were examined in deaerated acetonitrile, and the resulting data were evaluated in light of the Marcus theory of electron transfer to determine electron-exchange rate constants between manganese(III) and manganese(II) porphyrins. The investigated compounds are represented as (P)MnCl, where P = the dianion of dodecaphenylporphyrin (DPPX; X = H20, Cl12H8, or F20) or tetraphenylporphyrin (TPP). The electron transfer from semiquinone radical anion derivatives to (P)MnIIICl leads to formation of the corresponding MnII complex, [(P)MnIICl]−. The electron-exchange rate con…
Electron transfer mechanism in Shewanella loihica PV-4 biofilms formed at graphite electrode
2012
Abstract Electron transfer mechanisms in Shewanella loihica PV-4 viable biofilms formed at graphite electrodes were investigated in potentiostat-controlled electrochemical cells poised at oxidative potentials (0.2 V vs. Ag/AgCl). Chronoamperometry (CA) showed a repeatable biofilm growth of S. loihica PV-4 on graphite electrode. CA, cyclic voltammetry (CV) and its first derivative shows that both direct electron transfer (DET) mediated electron transfer (MET) mechanism contributes to the overall anodic (oxidation) current. The maximum anodic current density recorded on graphite was 90 μA cm − 2 . Fluorescence emission spectra shows increased concentration of quinone derivatives and riboflavi…