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Methyl viologen source

The monoanionic tungsten complex W[S2C2Ph(p-MeOPh)]3 has been reported to catalyze formation of hydrogen from water, using free radicals derived from methyl viologen as the source of electrons (112). The catalytic cycle has been proposed to involve sequential electron and proton transfer. [Pg.298]

Figure 9.18 Semilogarithmic plots of i vs. U for CH3-terminated -Si electrodes in contact with 10 mM methyl viologen at pH = 1.4 (grey continuous line), pH = 3.8 (blue continuous line), pH = 6.8 (blue dashed line), pH = 9.0 (black dashed line), and pH = 11.0 (black). Source Hamann and Lewis (2006). Figure 9.18 Semilogarithmic plots of i vs. U for CH3-terminated -Si electrodes in contact with 10 mM methyl viologen at pH = 1.4 (grey continuous line), pH = 3.8 (blue continuous line), pH = 6.8 (blue dashed line), pH = 9.0 (black dashed line), and pH = 11.0 (black). Source Hamann and Lewis (2006).
Fig. 3. Left EPR spectra of membrane-bound iron-sulfur proteins reduced by dithionite and methyl viologen. HP700 particles from spinach (A), soybean (B) and Anabaena chloroplasts (C). Spectra D and E are for chloroplasts prepared from mutant No. 8 of Scenedesmus obliquus and for TSF-IIa particles, respectively. Right plot of the EPR-signal amplitude at g=2.05 due to reduced iron-sulfur-protein vs. the P700 concentration in chloroplast and subchloroplast samples from various sources (1, unfractionated chloroplasts 2, D144 particles 3, TSF-1 particles 4. D144 from stroma 5, D144 from grana 6, HP700 particles 7, HP700 particles from soybean 8, chloroplasts from Anabaena 9, chloroplasts from mutant No. 8 of Scenedesmus obliquus-, and 10, TSF-2a particles. Unpublished results of B Ke and H Beinert (1973). Fig. 3. Left EPR spectra of membrane-bound iron-sulfur proteins reduced by dithionite and methyl viologen. HP700 particles from spinach (A), soybean (B) and Anabaena chloroplasts (C). Spectra D and E are for chloroplasts prepared from mutant No. 8 of Scenedesmus obliquus and for TSF-IIa particles, respectively. Right plot of the EPR-signal amplitude at g=2.05 due to reduced iron-sulfur-protein vs. the P700 concentration in chloroplast and subchloroplast samples from various sources (1, unfractionated chloroplasts 2, D144 particles 3, TSF-1 particles 4. D144 from stroma 5, D144 from grana 6, HP700 particles 7, HP700 particles from soybean 8, chloroplasts from Anabaena 9, chloroplasts from mutant No. 8 of Scenedesmus obliquus-, and 10, TSF-2a particles. Unpublished results of B Ke and H Beinert (1973).
Fig. 2. (A) K-band ESP-EPR spectra of the CPI complex (top) and Rb sphaeroides R26 reaction-center complex (bottom) in the charge-separated states [P700 -A,4 and [P870 Q4, respectively (B) X-band ESP-EPR spectra of spinach PS-I particles extracted with a hexane-MeOH mixture (a), reconstituted with protonated (b) and deuterated (c) vitamin Ki (C) ESP-EPR spectra of spinach PS-I particle in glycine buffer at pH 10.8 and untreated (a), reduced with 50 mM dithionite and 0,5 mM methyl viologen and dark-incubated (b), and the reduced sample dialyzed overnight against glycine buffer and reconcentrated (c). Figure source (A) Petersen, Stehlik, Gast and Thurnauer (1987) Comparison of the electron spin polarized spectrum found in plant photosystem I and in iron-depleted bacterial reaction centers with time-resolved K-band EPR evidence that the photosystem I acceptor is a quinone. Photosynthesis Res 14 22 (B) and (C) Snyder and Thurnauer (1993) Electron spin polarization in photosynthetic reaction centers. In J Deisenhofer and JR Norris (eds) The Photosynthetic Reaction Center, Vol 11 313,315. Fig. 2. (A) K-band ESP-EPR spectra of the CPI complex (top) and Rb sphaeroides R26 reaction-center complex (bottom) in the charge-separated states [P700 -A,4 and [P870 Q4, respectively (B) X-band ESP-EPR spectra of spinach PS-I particles extracted with a hexane-MeOH mixture (a), reconstituted with protonated (b) and deuterated (c) vitamin Ki (C) ESP-EPR spectra of spinach PS-I particle in glycine buffer at pH 10.8 and untreated (a), reduced with 50 mM dithionite and 0,5 mM methyl viologen and dark-incubated (b), and the reduced sample dialyzed overnight against glycine buffer and reconcentrated (c). Figure source (A) Petersen, Stehlik, Gast and Thurnauer (1987) Comparison of the electron spin polarized spectrum found in plant photosystem I and in iron-depleted bacterial reaction centers with time-resolved K-band EPR evidence that the photosystem I acceptor is a quinone. Photosynthesis Res 14 22 (B) and (C) Snyder and Thurnauer (1993) Electron spin polarization in photosynthetic reaction centers. In J Deisenhofer and JR Norris (eds) The Photosynthetic Reaction Center, Vol 11 313,315.
To suppress the electron and electron-hole recombination and continuously supply valence-band electron holes for an oxidative process, a sacrificial electron acceptor must be used to scavenge the electron in the conduction band [15,20], Oxygen is usually used in photocatalytic oxidation because of its ability to capture conduction-band electrons from most semiconductors [8]. The oxygen radical anion formed after the quenching of an electron is an additional oxidant, which is useful for oxidative waste degradation, but may be a source of side reactions in organic synthesis. To reduce such side reactions, the use of other electron acceptors such as methyl viologen and N2O has been reported [74]. [Pg.300]

The properties of purified sulfite reductase from spinach have been investigated in detail using methyl viologen as an artificial electron donor (Asada, 1967 Asada e/ al., 1969). In summary the enzyme can be resolved into two fractions both of which are essential for activity. One fraction can be replaced by bovine serum albumin while the other (sulfite reductase) exhibits the characteristics of a hemoprotein, containing 0.76 g atoms of Fe per molecular weight of 84,000. Unlike the sulfite reductase from other sources (see review by Roy and Trudinger, 1970), the purified spinach enzyme contains negligible amounts of flavin and catalyzes the reduction of hy-droxylamine, but not nitrite. The sulfite reductase from Allium exhibits similar... [Pg.212]

Fig. 6. Summary of the standard oxidation-reduction potentials of several dyes and the experimentally determined rate constants for their reduction by P430 . [DP, dipyridyls, preceded by the redox-potential values M(B)V, methyl (benzyl) viologens ST. safranine T MB, methylene blue]. Figure source Ke (1973) The primary electron acceptor of photosystem I. BiochimBiophysActa301 29. Fig. 6. Summary of the standard oxidation-reduction potentials of several dyes and the experimentally determined rate constants for their reduction by P430 . [DP, dipyridyls, preceded by the redox-potential values M(B)V, methyl (benzyl) viologens ST. safranine T MB, methylene blue]. Figure source Ke (1973) The primary electron acceptor of photosystem I. BiochimBiophysActa301 29.

See other pages where Methyl viologen source is mentioned: [Pg.409]    [Pg.239]    [Pg.349]    [Pg.349]    [Pg.92]    [Pg.346]    [Pg.221]    [Pg.23]    [Pg.5005]    [Pg.1622]    [Pg.2057]    [Pg.471]    [Pg.507]    [Pg.511]    [Pg.529]    [Pg.585]    [Pg.1039]    [Pg.5004]    [Pg.355]    [Pg.209]    [Pg.422]   


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Methyl viologen

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