Influence Of Electron Acceptors Research Articles

Influence of Electron Acceptors and Donors on the Dye-Photosensitized Decomposition of 2-Mercaptobenzothiazole

It has been shown that the quantum yield of the dye-photosensitized decomposition of 2-mercaptobenzothiazole (MBT) in aqueous solutions increases in the case of irradiation of dyes in the presence of electron acceptors. In the presence of electron donors, the quantum yields of the photosensitized decomposition reaction of MBT either remains unchanged or decreases. The donor thiocyanate and iodide ions were the exception; in this case, this was due to the formation of radical anions in the subsequent reactions of iodine and thiocyanate radicals with their anions, respectively. A mechanism has been suggested for the photosensitization of 2-mercaptobenzothiazole decomposition by dyes in the presence of electron acceptors and donors.

Influence of electron acceptors on hexanoic acid production by Clostridium kluyveri

Clostridium kluyveri was used for chain elongation of C2C4 fatty acids in stirred tank bioreactors. The influence of different electron acceptors (acetic acid, butyric acid and the mixture of both) on C6 fatty acid production was evaluated in presence of ethanol using similar molar alcohol/acid ratios around 3.5. Bottle batch assays without pH regulation and with only acetic acid as electron acceptor yielded a final C6 fatty acid concentration of 6.8 ± 0.6 g L−1. Then, pH-regulated bioreactors were operated at constant pH of 6.8. Under such conditions, the maximum growth rate was 0.039 h−1 obtained using acetic acid and butyric acid as electron acceptors, whereas the lowest growth rate was 0.010 h−1 with only butyric acid as electron acceptor. The maximum growth rate with acetic acid only, was similar, though slightly lower, as with the mixture of C2C4 fatty acids. Besides, the maximum productions of hexanoic acid were 11.8 g L−1, 13.1 g L−1 and 21.2 g L−1 using, respectively, acetic acid, butyric acid and the mixture of both acids as electron acceptors. Thus, the use of a mixture of acetic acid and butyric acid in presence of ethanol for chain elongation, at constant pH, proved to be efficient for hexanoic acid production.

A Systematic Study on the Influence of Electron-Acceptors in Phenanthrocarbazole Dye-Sensitized Solar Cells.

In this work, by conjugating 2-cyanoacrylic acid (CA), 4-(benzo[c][1,2,5]thiadiazol-7-yl)benzoic acid (BTBA), 4-(7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)benzoic acid (EBTBA), and 4-((7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)ethynyl)benzoic acid (EBTEBA) to a binary electron-donor diphenylamine-phenanthrocarbazole (DPA-PC), we systematically investigate the impacts of electron-acceptors upon energy level, energy gap, light-harvesting ability, photovoltaic parameter, and cell stability of donor-acceptor dyes in photoelectrochemical cells. In conjunction with an ionic liquid composite electrolyte, the DPA-PC dye with EBTEBA as electron-acceptor yields a high power conversion efficiency of 8% and an outstanding stability after a 1000 h aging test under the soaking of full sunlight at 60 °C in a dye-sensitized solar cell. Femtosecond fluorescence up-conversion measurements have suggested that energy relaxation and electron injection both occur to dye molecules in the nonequilibrium excited states. Moreover, the time constants of injecting electrons from dye molecules in the excited states to titania are very dispersive for over 1 order of magnitude, mainly owing to the broad energy distribution of excited states.

Influence of electron acceptors on the kinetics of metoprolol photocatalytic degradation in TiO2 suspension. A combined experimental and theoretical study

The presence of electron acceptors improves the photocatalytic degradation of metoprolol (MET). Reaction intermediates were studied in detail. The interactions of reactive radical species with MET were theoretically investigated by DFT computations.

96/03797 Low-temperature depolymerization of coal under the influence of electron acceptors

96/03797 Low-temperature depolymerization of coal under the influence of electron acceptors

Nitrogen NMR assessment of interactions between nitroso, cyano and acetyl groups across aliphatic systems

AbstractThe nitrogen NMR shieldings (Δσ, equivalent to —Δδ on the frequency scale of chemical shifts) of the NO group in nitrosoalkanes are shown to be a sensitive probe to electron‐withdrawing effects of substituents and to steric strain effects. The former produce high‐field (low‐frequency) shifts, which can amount to about 90 ppm, while the latter result in considerable low‐field (high‐frequency) shifts of the NO nitrogen resonance. The CN nitrogen shieldings show less pronounced low‐field (high‐frequency) shifts under the influence of electron acceptors. The signs and magnitudes of the observed effects are explained in terms of semi‐empirical molecular orbital calculations of the shieldings and molecular mechanics evaluations of strain energies. The overall picture of relationships between the NO and CN nitrogen shieldings and electron charge migration within the molecules concerned is in accord with that obtained in earlier studies of solvent‐induced effects on the nitrogen shieldings in alkyl cyanides and nitro compounds.

Reactions of thermalizing electrons in a condensed polar medium

The influence of electron acceptors on the yield of trapped electrons in frozen aqueous solutions is examined, and the results of picosecond radiolysis is discussed. It has been shown that the correlations observed cannot be explained if thermal electrons only take part in reactions occurring in such matrices, whereas they can be correctly interpreted assuming that epithermal electrons are also capable of reacting with acceptors in a condensed medium. Experimental data obtained are discussed on the basis of these concepts. The times needed for thermalization, solvation and capture have been evaluated, and the rate constants of the reactions of epithermal electrons computed.

The maximum yield of separated ion pairs in polar ?glasses,? ?-irradiated at 77�K

1. The influence of electron acceptors on the process of separation of primary ion pairs, arising in the radiolysis of glassy polar substances (aqueous solutions of alkali and alcohols) at 77°K was studied. 2. The introduction of electron acceptors leads to a substantial increase (by ∼70%) in the yield of separated ion pairs in comparison with the pure matrices.

The influence of electron-acceptors on the photo-conductivity of polymeric semiconductors

1. The creation of a heterophase system between the polymer with a system ofπ-conjugation and an electron acceptor leads to an increase in photoconductivity by a factor of 103–108 over the photoconductivities of the polymer and the acceptor. 2. The dependence of the photoconductivity on the wavelength in the long-wave region is determined by the absorption spectrum of the polymer.