ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The synthesis of four electropolymerizable 2,2′-bipyridinium salts with tuned reduction potential (E1∘) is described (N,N′-ethylene-4-methyl-4′-vinyl-2,2′-bipyridinium dibromide (4; E1∘ =-0.48 V), 4-methyl-N, N′-(trimethylene)-4′-vinyl-2,2′-bipyridinium dibromide (5; E1∘= -0.66 V), N,N′-ethylene-4-methyl-4′-[2-(1H-pyrrol-1-yl)ethyl]-2, 2′-bipyridinium bis(hexafluorophosphate) (6b; E1∘= -0.46 V), and 4-methyl-4′-[2-(1H-pyrrol-1-yl)ethyl]-N, N′-(trimethylene)-2,2′-bipyridinium bis(hexafluorophosphate) (7b; E1∘= -0.66 V)). E1∘-Tuning is based on the torsional angle C(3)-C(2)-C(2′)-C(3′), imposed by the N,N′-ethylene and N,N′-(trimethylene) bridge. The vinylic compounds 4 and 5 undergo cathodic, the pyrrole derivatives 6b and 7b anodic electropolymerization on glassy carbon electrodes from MeCN solutions, yielding thin, surface-confined films with surface concentrations of redox-active material in the range 5 · 10-9 〈 Γ 〈 2.10-8 mol/cm2, depending on experimental conditions. The modified electrodes exhibit reversible ‘diquat’ electrochemistry in pure solvent/electrolyte. Copolymerization of 6b or 7b with pyrrole yields most stable electrodes. Bi ayer-film-modified electrodes were prepared by sequential electropolymerization of the monomers. The assembly electrode/poly-6b/poly-7b behaves as a switch, it transforms - as a Schmitt trigger - an analog input signal (the electrode potential) into a digital output signal (redox state of the outer polymer film). Forward-(electrode/poly-7b/poly-6b) and reverse-biased assemblies (electrode/poly-6b/poly-7b) were coupled to the electrochemical reduction of redox-active solution species, e.g. N- (cyanomethyl)-N′-methyl-4,4′-bipyridinium bis(hexafluorophosphate) (8). Zener-diode-like behavior was observed. Aspects of redox-polymer multilayer-film assemblies, sandwiched between two electronic conductors, are discussed in terms of molecular electronic devices.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19940770134
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