Monocation radical

In bacteria (Escherichia coli), paraquat is concentrated, reduced to the monocation radical, and combines with molecular oxygen to produce the superoxide radical within the cell. Copper and iron are essential mediators in bactericidal effects. The cytoplasmic membrane is the target organelle in paraquat toxicity to E. coli, and extent of damage correlates positively with levels of these metals (Kohen and Chevion 1988). 

Figure 1. RR spectra with 406.7nm excitation for ZnOEP (0.5ii, bottom) in CH2Cil2 (50mW incident laser power) and for solutions with increasing amounts of monocation radical formed by electrolysis at 0.85V vs. SCE (15mW). Each scan was obtained with a fresh sample (Reproduced from Ref. 5. Copyright 1986 American Chemical Society.)...

Bipyrylium dication. 2,2, 6,6 -tetra-t-butyl-, reduction. ESR of monocation radical, 60, 90... 

Differential pulse polarography measurements of 2,2 -(p-phenylene)bis-(1,3-benzodithiolium) bis(tetrafluoroborate) in acetonitrile show two reductions corresponding to the monocation-radical and the neutral compound 141 these species are highly unstable. ... 

The monocation radical of dibenzodioxine can be prepared electrochemically and isolated as a stable perchlorate [297] if the medium is not dry, hydroxylated and further oxidized products are obtained. 

In bacteria (Escherichia coli), paraquat is concentrated, reduced to the monocation radical, and combines with molecular oxygen to... 

Figure 11.17 illustrates a representative process for the catalytic conversion of hydrogen ions to hydrogen gas. It begins (A, Fignre II.I7) with excitation of the photosensitizer [Ru(bpy)3] to afford [Ru(bpy)3], which is quenched by the dicationic electron mediator methyl viologen in step C to afford a monocation radical. The electron from... 

To improve the SNR, several signals measmed at the same mirror position are averaged. As a result, several thousandfold triggering of the reaction is required to achieve appropriate spectral resolution and SNR. For example, to study the generation of the monocation radical of heptylviologen (HV +) upon a potential step from —0.2 to —0.55 V (Ag-AgCl) on a gold electrode with l(X)-p,s-iesolved ATR-SEIRA spectroscopy (Fig. 4.55), potential modulation cycles were repeated about 2000 times with spectral resolution of 8 cm [473]. 

An interesting electrochemical and spectroelectrochemical behavior has been reported for zinc porphyrin-cored triarylamine-dendrimers of first and second generation [131]. The first-generation dendrimer was oxidized by a total of 6e that were assigned to (i) le oxidation of the zinc porphyrin generating the monocation radical (ii) le oxidation of one of the triarylamine units and (iii) a 4e oxidation process attributed to the three remaining triarylamine units and to the oxidation of the zinc porphyrin to the dication species. The zinc porphyrin ring oxidation... 

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