Formation of Triradical Trications from Hexaquaternary Salts Derived from 4,4'-Bipyridine

McGeachie, Joanne; Summers, L. A.

doi:10.1515/znb-1986-1011

Cited by 10 publications

(6 citation statements)

References 8 publications

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“…The poly-L-lysines (PLLs) used were PLL19, PLL46, PLL120, and PLL268, (Sigma Aldrich) with the numbers referring to the average number of lysine monomers per molecule. 1,1 '-Bis-(3-(l '-methyl-(4,4'-bipyridinium)-1 -yl)-propyl)-4,4'-bipyridinium hexaperchlorate (BMBB) was synthesized by McGeachie and Summers (1986). All other materials were of analytical grade.…”

Section: Materials and Methods Chemicalsmentioning

confidence: 99%

Estimation of the pore size of the large-conductance mechanosensitive ion channel of Escherichia coli

Cruickshank

Minchin

Dain

et al. 1997

Biophysical Journal

240

223

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The open channel diameter of Escherichia coli recombinant large-conductance mechanosensitive ion channels (MscL) was estimated using the model of Hille (Hille, B. 1968. Pharmacological modifications of the sodium channels of frog nerve. J. Gen. Physiol. 51:199-219) that relates the pore size to conductance. Based on the MscL conductance of 3.8 nS, and assumed pore lengths, a channel diameter of 34 to 46 A was calculated. To estimate the pore size experimentally, the effect of large organic ions on the conductance of MscL was examined. Poly-L-lysines (PLLs) with a diameter of 37 A or larger significantly reduced channel conductance, whereas spermine (approximately 15 A), PLL19 (approximately 25 A) and 1,1'-bis-(3-(1'-methyl-(4,4'-bipyridinium)-1-yl)-propyl)-4,4'-b ipyridinium (approximately 30 A) had no effect. The smaller organic ions putrescine, cadaverine, spermine, and succinate all permeated the channel. We conclude that the open pore diameter of the MscL is approximately 40 A, indicating that the MscL has one of the largest channel pores yet described. This channel diameter is consistent with the proposed homohexameric model of the MscL.

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Section: Materials and Methods Chemicalsmentioning

confidence: 99%

Estimation of the pore size of the large-conductance mechanosensitive ion channel of Escherichia coli

Cruickshank

Minchin

Dain

et al. 1997

Biophysical Journal

240

223

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“…(iii) Charge transport is also expected to depend on the concentration of redox centers in the (PV B −NR) 1 layer. An estimation of the film thickness can be obtained from averaged apparent density values informed for other systems (2.1 ± 0.3) g cm -3 . , If the mass increments measured from QCM experiments are considered, the thickness of the assembly can be estimated to be around 10 nm. The charge needed to reduce the (PV B −NR) 1 layer (Figure ) allowed us to evaluate the concentration of V •+ (PV B ).…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Behavior of Nitrate Reductase Immobilized in Self-Assembled Structures with Redox Polyviologen

et al. 2003

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We report on a novel bioelectrode based on self-assembled multilayers of nitrate reductase (NR) intercalated with a cationic viologen-functionalized polyvinylpyridinium (PV) polymer specially synthesized for this purpose. Different samples of polymer proved to have varying substitution ratios, according to NMR experiments. The electrostatic self-assemblies were built up on a thiol-modified gold surface using a strategy previously described by Hodak et al. The electrochemical behavior of PV and the response of the electrodes toward nitrate were followed by cyclic voltammetry. The catalytic currents obtained were proportional to the number of NR-immobilized layers, as well as to the polymer substitution degree, proving that the enzyme remained active under immobilization conditions and that it can be regenerated by PV redox moieties. Experiments with quartz crystal microbalance electroacoustic impedance were carried out to follow quantitatively the multilayer film formation. The kinetics of the adsorption processes and the influence of the ionic strength are investigated. The evaluation of water and ion exchange during the reduction of PV is also achieved from electroacoustic and electrochemical experiments. Results indicate an important water exchange associated with the polymer redox behavior.

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“…The viologens are usually prepared by the Menschutkin reaction of 4,4 0 -dipyridyls and dibromoalkanes in aprotic solvents, e.g., acetonitrile, dimethyl-formamide, and dimethylsulfoxide. The reaction usually results in the formation of a mixture of mono-and multiquatenary salts with low molecular weight [5][6][7]. A possible explanation of this effect is that the positive charges in the aromatic rings are separated by the relatively short aliphatic chain, and the electrostatic repulsion between them hinders the further growth of the molecules [8].…”

Section: Introductionmentioning

confidence: 99%

The Electrochemical Properties of Some Alkylviologens

1998

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Ethyl-, and butylviologens were prepared by the Menschutkin reaction of 4,4 0 -dipyridyl and 1,2-dibromoethane and 1,4-dibromobutane. Elemental analysis and 1 H-NMR spectra showed that products consisted of symmetrical and asymmetrical substituted dipyridyls. Electrochemical reduction of these compounds in KBr and HCl solutions has been studied by the voltammetry method. The reduction process proceeds through several electrochemical and protonation steps, depending on the viologen structure and pH of the solution. The process results in a film formation on the electrode surface. The film is partly electroactive in the KBr solution, but completely passive in HCl. Reaction schemes have been proposed to explain this phenomenon.

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Formation of Triradical Trications from Hexaquaternary Salts Derived from 4,4'-Bipyridine

Cited by 10 publications

References 8 publications

Estimation of the pore size of the large-conductance mechanosensitive ion channel of Escherichia coli

Estimation of the pore size of the large-conductance mechanosensitive ion channel of Escherichia coli

Electrochemical Behavior of Nitrate Reductase Immobilized in Self-Assembled Structures with Redox Polyviologen

The Electrochemical Properties of Some Alkylviologens

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