13096-46-3Relevant articles and documents
Study of electron transfer reactions associated with benzyl viologen-β-cyclodextrin complexation in buffer solution of pH 7: Equilibrium and kinetic aspects
Perveen, Shazia,Naqvi, Iftikhar Imam,Masood, Summyia
, p. 1981 - 1985 (2020)
In this study, complex formation of benzyl viologen dication (BzV2+) with β-cyclodextrin (β-CD), in its different oxidation states, had been studied in buffer solution of pH 7, through cyclic voltammetry. In buffer solution of pH 7, extensive d
Magnetic Resonance Studies of Some Bipyridylium Diactions and Cation Radicals
Rieger, Anne L.,Rieger, Philip H.
, p. 5845 - 5851 (1984)
In an attempt to resolve ambiguities in and contradictions among previous studies, NMR spectra of the methylviologen (MV2+), benzylviologen (BV2+), and diquat (DQ2+) dications and ESR spectra of the corresponding cation radicals were reinvestigated.ESR spectra of the cation radicals in methanol solution had sufficiently good signal-to-noise ratios and resolution to permit completely unambiguous determinations of hyperfine coupling constants.ESR intensity data showed that MV+. and BV+. precipitate as ESR-inactive solids at low temperature and that MV+. associates to micelle-like solution particles at high concentration.The intensity data show no evidence for formation of dimers or other low molecular weight polymers.Literature reports of dimer formation in methanol solution are the result of temperature-dependent saturation of the ESR spectra.Line broadening of NMR spetra of MV2+, BV2+, or DQ2+ in the presence of traces of cation radical was used to provide unambiguous assignments of ESR hyperfine coupling constants, and to give good estimates of the cation radical concentrations and the dication/cation radical electron exchange rate constant.The NMR line broadening experiments also provide an estimate of the rate of conformational change of the ethylene bridge in the diquat cation radical.
Kinetics of Reduction of Eight Viologens by dithionite Ion
Tsukahara, K.,Wilkins, R. G.
, p. 2632 - 2635 (1985)
The rate constants are reported for reduction by dithionite of methyl viologen, diquat, and six other diquaternary salts of 4,4'-bipyridine, 2,2'-bipyridine, and 1,10-phenanthroline.The active reductant is the SO2(1-) radical, and rate constants vary from >5*108, to 8.5*103 M-1s-1 with increasing negative reduction potential of the viologen.It is concluded that self-exchange rate constants for the viologens (X2+/+ couple) are ca. 108 M-1s-1, and it is supported by the results of a cross-reaction involving two viologens, the second-oreder rate constant being measured by pulse radiolytic techniques.
Air-stable surface charge transfer doping of MoS2 by benzyl viologen
Kiriya, Daisuke,Tosun, Mahmut,Zhao, Peida,Kang, Jeong Seuk,Javey, Ali
, p. 7853 - 7856 (2014)
Air-stable doping of transition metal dichalcogenides is of fundamental importance to enable a wide range of optoelectronic and electronic devices while exploring their basic material properties. Here we demonstrate the use of benzyl viologen (BV), which has one of the highest reduction potentials of all electron-donor organic compounds, as a surface charge transfer donor for MoS2 flakes. The n-doped samples exhibit excellent stability in both ambient air and vacuum. Notably, we obtained a high electron sheet density of ～1.2 × 1013 cm-2, which corresponds to the degenerate doping limit for MoS2. The BV dopant molecules can be reversibly removed by immersion in toluene, providing the ability to control the carrier sheet density as well as selective removal of surface dopants on demand. By BV doping of MoS2 at the metal junctions, the contact resistances are shown to be reduced by a factor of >3. As a proof of concept, top-gated field-effect transistors were fabricated with BV-doped n+ source/drain contacts self-aligned with respect to the top gate. The device architecture, resembling that of the conventional Si transistors, exhibited excellent switching characteristics with a subthreshold swing of ～77 mV/decade.
The Viologen Cation Radical Pimer: A Case of Dispersion-Driven Bonding
Geraskina, Margarita R.,Dutton, Andrew S.,Juetten, Mark J.,Wood, Samuel A.,Winter, Arthur H.
supporting information, p. 9435 - 9439 (2017/08/01)
The π bonds between organic radicals have generated excitement as an orthogonal interaction for designing self-assembling architectures in water. A systematic investigation of the effect of the viologen cation radical structure on the strength and nature of the pimer bond is provided. A striking and unexpected feature of this π bond is that the bond strength is unchanged by substitution with electron-donating groups or withdrawing groups or with increased conjugation. Furthermore, the interaction is undiminished by sterically bulky N-alkyl groups. Theoretical modeling indicates that strong dispersion forces dominate the interaction between the radicals, rationalizing the insensitivity of the bonding interaction to substituents: The stacking of polarizable π radicals leads to attractive dispersion forces in excess of typical dispersion interactions of small molecules and helps overcome the Coulombic repulsion of bringing two cationic species into contact.
ELECTROCHROMIC SALTS, SOLUTIONS, AND DEVICES
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Page 34, (2008/06/13)
Electrochromic salts of dicationic viologens such as methyl viologen and benzyl viologen associated with anions selected from bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and tris(trifluoromethylsulfonyl)methide are produced by metathesis with the corresponding viologen dihalide. They are highly soluble in molten quarternary ammonium salts and together with a suitable reductant provide electrolyte solutions that are used in electrochromic windows.
Mechanistic implications of a linear free-energy correlation of rate constants for the reduction of active- and Met-R2 forms of E. coli ribonucleotide reductase with eight organic radicals
Dobbing, A. Mark,Borman, Christopher D.,Twitchett, Mark B.,Leese, David N.,Salmon, G. Arthur,Sykes, A. Geoffrey
, p. 2206 - 2212 (2007/10/03)
Cross-reaction rate constants k12 (22 °C) at pH 7.0 have been determined for the reduction of Fe(III)2 and tyrosyl-radical-containing active-R2 from E. coli ribonucleotide reductase with eight organic radicals (OR), e.g., MV·+ from methyl viologen. The more reactive OR's were generated in situ using pulse radiolysis (PR) techniques, and other OR's were generated by prior reduction of the parent with dithionite, followed by stopped-flow (SF) studies. In both procedures it was necessary to include consideration of doubly-reduced parent forms. Values of k12 are in the range 109 to 104 M-1 s-1 and reduction potentials E1/(o) for the OR vary from -0.446 to +0.l94 V. Samples of E. coli active-R2 also have an Fe2(III) met-R2 component (with no Tyr·), which in the present work was close to 40%. From separate experiments met-R2 gave similar k12 rate constants (on average 66% bigger) to those for active-R2, suggesting that reduction of the Fe2/(III) center is the common rate-limiting step. A single Marcus free-energy plot of log k12 - 0.5 log f vs - E1/(o)/0.059 describes all the data, and the slope of 0.54 is in satisfactory agreement with the theoretical value of 0.50. It is concluded that the ratelimiting step involves electron transfer. In addition, the intercept at -E1/(o)/0.059 = 0 is 5.94, where values of the reduction potential and self-exchange rate constant for met-R2 contribute to this value. To maintain electroneutrality at the ~10 A buried active site H+ uptake is also required. For both e- and H+ transfer the conserved pathway Trp-48, Asp-237, His-118 to Fe(A) is a possible candidate requiring further examination.
Hypoxia-Selective Antitumor Agents. 4. Relationships between Structure, Physicochemical Properties, and Hypoxia-Selective Cytotoxicity for Nitracrine Analogues with Varying Side Chains: The "Iminoacridan Hypothesis"
Denny, William A.,Atwell, Graham J.,Anderson, Robert F.,Wilson, William R.
, p. 1288 - 1295 (2007/10/02)
The nitroacridine derivative nitracrine is a potent hypoxia-selective cytotoxin for mammalian cells in culture.In an attempt to modulate the degree of hypoxia selectivity among this class of compounds, we have studied a series of side-chain analogues of nitracrine.Both the electronic and steric properties of the side chain are shown to be important in determining the hypoxia selectivity of the compounds, by controlling the degree of aminoacridine/iminoacridan tautomerism.Studies with the repair-defective Chinese hamster cell line UV4 indicate that the cytotoxicity ofall the compounds is due to nitro group reduction and subsequent macromolecular adduct formation.However, compounds such as the 9-amino derivative, which exist totally as the aminoacridine tautomer, form much less lethal lesions than the 9-alkylamino derivatives, which exist to varying degrees in the iminoacridan conformation.For the whole set of compounds, the degree of hypoxia-selective cytotoxicity correlates well with the proportion of iminoacridan tautomer present.
Viologen-mediated Reductive Dehalogenation of α-Halogeno Ketones
Park, Kwanghee Koh,Lee, Chul Woo,Oh, Si-Young,Park, Joon Woo
, p. 2356 - 2357 (2007/10/02)
Various α-halogeno ketones undergo reductive halogenation to the corresponding ketones almost quantitatively with sodium dithionite using viologen as an electron-transfer catalyst in organic solvent-water two-phase systems.
Hypoxia-selective antitumor agents. 1. Relationships between structure, redox properties and hypoxia-selective cytotoxicity for 4-substituted derivatives of nitracrine
Wilson,Anderson,Denny
, p. 23 - 30 (2007/10/02)
The nitroacridine derivative 9-[[3-(dimethylamino)propyl]amino]-1-nitroacridine (nitracrine) is selectively cytotoxic to hypoxic tumor cells in culture. However, the compound undergoes reductive metabolism too rapidly, with the reduction not being sufficiently inhibited by molecular oxygen in aerobic tissues, for it to demonstrate the same activity in vivo. In a search for derivatives with lower reduction potentials, we have synthesized and evaluated a series of derivatives bearing 4-substituents with a wide range of electronic properties. The one-electron reduction potentials (E(1)) of these compounds, when compared under conditions of equivalent ionization, were highly correlated with σ(p) values. However, at pH 7 the influence of substituent electronic properties was modified by prototropic equilibria, with the basic nature of the acridine limiting the extent to which ring substituent electronic effects can be used to modulate reduction potential of the 1-nitro group. Nevertheless, comparison of the kinetics of the killing of AA8 cells under hypoxia suggests that some metabolic stabilization of the compounds can be achieved by the use of electron-donating substituents, with such compounds retaining the hypoxia-selective toxicity of nitracrine in cell culture. However, the 4-substituted nitracrines show no clear relationship between E(1) and cytotoxic potency, in distinct contrast to simpler nitroheterocycles such as nitroimidazoles.
