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
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.
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.
, 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.
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.
