Viologen-containing polymer film

In another report, layer-by-layer (LbL) self-assembly deposition was employed to prepare the acceptor-sensitizer dyad polyelectrolyte film in DSSC.48 The viologen-containing polymer film with bromide as the counterions... 

A substituted pyrrole (Fig. 7c) was electropolymerised across the pores of an alumina membrane [83] and the resultant polymer film then acted as a permselective membrane across which anions could cross. This was then used to separate an analyte solution from an internal sensing solution containing nitrate reductase enzyme and methyl viologen. 

An optical sensing device for surface plasmon resonance (SPR) was proposed for determination of the concentration of phenolic compounds in water. The phenols become adsorbed on a thin gold or silver film that has been spin-coated with a sol-gel layer containing receptor molecules. Best SPR signals for phenolic compounds were obtained when the receptors were viologen-type polymers with polymeric counterions (179). The SPR signal intensity was concentration dependent and had to be calibrated for individual phenolic compounds . ... 

The peak shift due to aggregation is observed not only in LBK films containing azobenzene chromophores, but also for other chromophores with extended Ji-systems, such as viologen polymers. For monolayers of the poly(p-phenylene sulfonate) 9/ dioctadecyldimethylammonium bromide (DODA) complex, the peak shift due to aggregation results in a piezo-chromic effect—that is, upon compression of the monolayer, a significant shift of the poly(p-phenylene sulfate) A band is observed (see Figure 6.9). This photochromic effect has been shown to be based on the improved 7t-Jt interaction upon compression of the monolayer. ... 

The immobilization of an active species into a conducting polymer layer allows one to obtain active electrodes for the reduction of various organic halides. Polypyrrole containing viologen electrodes appear to be active for the reduction of alkyl dibromide [177] or hexachloroacetone [178], Cobalt-bipyridyl-polypyrrole films are active electrodes for the reduction of alkyl chloride [107], The mechanism of this reaction is similar to that observed in the homogeneous phase. This confinns one of the major interests of the modified conductive polymer electrodes, i,e. the possibility of performing catalytic reactions with smaller amounts of active catalyst in comparison to homogeneous catalysis, and then to avoid problems related to the separation of products from the solution which contains this catalyst. 

Havinga, E. E., Van Horssen, L. W., ten Hoeve, W., Wynberg, H., and Meijer, E. W., Self-doped water soluble conducting polymers, Polym. Bull., 18, 277-281 (1987). Bidan, G., Deronzier, A., and Moutet, J. C., Electrochemical coating of an electrode by a polypyrrole film containing the viologen (4,4 -bipyridinium) system, J. Chem. Soc. them. Commun., 1185-1186 (1984). 

Fig. 29) Two adjacent microelectrodes were derivatized by stepwise electrochemical polymerization. First a polymer viologen film (BPQ )n (related to 4) on one electrode and then a polyvinylferrocene (PVFc) film (related to 11) on the other electrode were obtaineo from the corresponding monomers by reductive and oxidative depositions, respectively. Small spacing between the two microelectrodes is crucial because for these materials the maximum conductivity is much lower than that of polymers such as 14,17, and 20 The redox levels are as follows E (BPQ +/+) = —0.55 V, E°(PVFc /°) = 0.4 V vs SCE. The redox reaction at the interface immersed in an aqueous electrolyte containing LiCIO occurs at a good rate only in one direction because the reaction in Eq. (20) is thermodynamically downhill. 

In the latter example and others involving polypyrrole films electroformed from a complex between a transition metal (Ru(II)) and a bi- or terpyridine-substituted pyrrole [201, 202], the electron self-exchange was ensured by either the viologen or Ru(II) units and not by the polymer. As a matter of fact, the PPy matrix was undoped when poly(3) was used for electrocatalytic reduction experiments or overoxidized when the films containing ruthenium(II)-based complexes were involved in oxidation experiments [201, 202]. 

Kamogawa and coworkers " reported a color change displayed by films of poly(A -vinyl-2-pyrrolidone) that contain aryl viologens and films of copolymers that contain AiA -dimethylacrylamide with vinyl viologen. Abruna and Bard and Burgmayer and Murry studied electrode films of viologen polymers, which have been prepared from preformed polymers 43 and 44 (Scheme 17). Thus electrode... 

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