Structure polythiophenes

Recently novel polyelectrolytes 8 have been incorporated into polythiophene structures and found to generate a mechanically strong electroactive deposit.16... 

In this section, the structural studies of polythiophenes are reviewed the influence of structure on properties is considered in subsequent sections. The description of polythiophene structures include the alkyl-substituted thiophenes, such as poly(3-alkylthiophenes) (P3ATh s). 

The need for high electronic conductivity has meant that work has focused on the use of the so called conducting polymers, exemplified by polypyrrole, polyaniline and polythiophene (Structures 1 to 3). These materials must be in their p-doped (partially oxidized) states (right hand side of eq. 1, for example) to exhibit sufficient electronic conductivity. Unfortunately, the p-doped polymers are cationic and will therefore tend to exclude the protons needed for the fuel cell reactions. To circumvent this problem, composites of conducting polymers with cation exchange polymers have been used. Thus p-doped polypyrrole / poly(styrene-4-sulphonate) (PSS), for example, exhibits both proton and electron conductivity (8). 

C. Roux, J. Y. Bergeron, and M. Leclerc, Ther-mochromic properties of polythiophenes structural aspects, Makromol. Chem. /94 869 (1993). 

The potentiod5mamically electropolymerized metal complexes exhibit both the typical behavior of the polythiophene structure and the metal complex. The same S5mthetic strategy described by Figure 13.25 was used to prepare the fullerene derivatives shown in Figure 13.27, which are potentially useful for photovoltaic energy conversion. ... 

Different color transitions are obtained by simply changing the molecular structure of the polythiophene and then oxidizing or reducing it. Figure C. p. 93. shows the different colors obtained by taking the neutral form... 

The diversity of conducting polymers is best illustrated by Krivoshei and Skorobogatov s book,15 although many more examples have since been reported. The most widely studied classes, from an electrochemical point of view, are the polypyrroles, polythiophenes, and polyanilines21 22 (Structures 2-4), and these are the focus of this chapter. A wide... 

Besides synthesis, current basic research on conducting polymers is concentrated on structural analysis. Structural parameters — e.g. regularity and homogeneity of chain structures, but also chain length — play an important role in our understanding of the properties of such materials. Research on electropolymerized polymers has concentrated on polypyrrole and polythiophene in particular and, more recently, on polyaniline as well, while of the chemically produced materials polyacetylene stih attracts greatest interest. Spectroscopic methods have proved particularly suitable for characterizing structural properties These comprise surface techniques such as XPS, AES or ATR, on the one hand, and the usual methods of structural analysis, such as NMR, ESR and X-ray diffraction techniques, on the other hand. 

The synthesis of poly(isothianapthene) (PITN) is an example of the second generation of conducting polymers, which have been prepared in order to produce a material with specific properties. Given the two inequivalent structures of polythiophene which give... 

Polythiophenes for Structured and Polarized Polymer Light-Emitting Diodes... 

Ho et al. were able to verify the a-helical shape of the polymer by circular dichroism (CD) spectra. No structural elements were observed until the formation of the double helical DNA at which point they observed a right-handed a-helix in the polythiophene backbone. Their work demonstrates the power of fluorometric detection as they noted a seven order of magnitude increase in detection sensitivity (20 fM in 200 pi) simply through the use of fluorometric detection as opposed to UV-vis absorption. The polymer in solution has a high fluorescence yield with a maximum at 530 nm (Fig. 11a). Upon formation of the duplex the fluorescence is significantly quenched (Fig. lib), while with the addition of the complementary DNA and triplex formation, the fluorescence intensity is enhanced by a factor of 5 (Fig. 11c). The inherent sensitivity of the spectral shift even allowed distinction between DNA with only one and two mismatched bases (Fig. lOBd, e). 

Nilsson et al. designed an experiment to test the ability of a polymer to directly detect conformational changes within peptide/protein structure [27]. Using the zwitterionic polythiophene derivative, POWT, they succeeded in detecting the distinct conformations of synthetic peptides. The mechanism was concluded to be based on the polymer side chains charged interactions and hydrogen bonding with the proteins. 

Fig. 17 (a) Chemical structure of polythiophene poly((3,3"-di[(S)-5-amino-5-carbonyl-3-oxapen-tyl]-[2,2 5 2"])-5-,5"-terthiophenylene hydrochloride), PONT, (b) Emission spectra of 6.5 pM PONT—HC1 (on a chain basis) in 25 mM HC1 (black spectrum), 25 mM HC1 with 5.0 pM of native bovine insulin (blue spectrum), 25 mM HC1 with 5.0 pM fibrillar bovine insulin (red spectrum). The emission spectra were recorded with excitation at 400 nm [31]... 

Le Bouch N, Auger M, Leclerc M (2008) Structure and segmental motions in a substituted polythiophene a solid-state NMR study. Macromol Chem Phys 209 2455-2462... 

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