Polythiophene derivatives structures

Leclerc, M., and M. Paid. 1997. Electrical and optical properties of processable polythiophene derivatives Structure-property relathionships. Adv Mflter 9 1087-1094. 

M. Leclerc, K. Paid, Electrical and optical properties of processahle polythiophene derivatives structure-property relationships, Advanced Materials 1997, 9,1087. 

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. 

Figure 3.12. Molecular structure of the amphiphilic polythiophene derivative discussed in the text.

Mechanically durable and structurally flexible polythiophene derivatives have been prepared that are useful as semiconducters in thin film field effect transistors and are soluble in chlorobenzene. Materials prepared from these agents have a bandgap between 1.5 and 3.0 eV that enhance their function as film transistors. 

This Hnear dependence has been confirmed by Halls et al. using the same bilayer structure but employing PPV as the electron donor [44]. The authors estimated the exciton diffusion length of PPV to be in the range of 6-8 nm from both the spectral response and the absolute efficiency [44]. Later Roman et al. demonstrated optical modeling to be a useful tool for the optimization of such bilayer solar cells, which in their case was based on a polythiophene derivative and Ceo [89]. The optical modeling was detailed by Petterson et al. [46]. 

Roux, C., and M. Leclerc. 1994. Structure-property relationships in thermochromic polythiophene derivatives. Macromol Symp 87 (Polymers Progress in Chemistry and Physics) l-4. 

Note that polythiophene derivatives can be reduced in the negative direction (n-doping) however the reduction peak (redox potential, shape, reversibility, etc.) is strongly dependent on the structure of the monomers and on the electrochemical conditions. 

A survey of the polythiophene derivatives that have been considered and tested as active electrode material in electrochemical capacitors can be roughly divided between wide- and narrow-bandgap derivatives. The structure of monomers of the corresponding polymers is presented in Schemes 15.1-15.4. 

Scheme 15.2 Structures of wide-bandgap polythiophene derivatives...

Scheme 15.3 Structures of narrow-bandgap polythiophene derivatives [16, 22, 43]...

Scheme 15.4 Structures of narrow-bandgap polythiophene derivatives cyclopenta[2,1-b 3,4-bf Jdithiophene-4-one (CDT) and dithieno[3,4-b 3, 4 -d]thiophene (DTTI)...

FIGURE 13.20 Polythiophene-based probes for amyloid and protein aggregate detection (a) chemical structures of polythiophene derivatives PONT (b) emission spectra of PTAA in free solution (c) emission spectra of PTAA solution complexed with native insulin or amyloid insulin, and (d) kinetics of insulin fibrillation. Reprinted with permission from [190]. Copyright 2005 American Chemical Society. 

Typical absorption spectra of the conjugated polymers are shown in Fig. 10 for PPV, CNMBC polymer PDSiPV [90J, film and polythiophene derivative PURET [79,105] film. The ab.sorption maximum at 420 nm of the fully converted PPV film is red shifted from that of precursor polymer [106]. The other peaks are located at 250 and below 200 nm. In comparison with the theoretical energy dispersion based on the 7r-band structure [107], the rr—tt transition corresponding to the band gap is assigned at 420 nm. For the other peaks, it was suggested that the peak at 200 nm corresponds to the tt—tt transition for ir-electron states localized within a... 

Another remarkable example of conjugated polymer exhibiting a supramolecular structure deeply affecting the physical and electronic properties of the material is provided by the regiorandom and regioregular polythiophene derivatives. 

Zhao X.Y, Wang M. and Liu H.J. (2008), Structure dependence of photochromism of azobenzene-functionalized polythiophene derivatives./owrna/ of Applied Polymer Science, 108 pp. 863-869. 

The application to the case of the polymers of the bilayer heterojunction structure that has been used successfully with molecular semiconductors [139] has recently been reported. The fullerene ) provides a useful high electron affinity semiconductor, and it is found that blends of this with a range of soluble PPV and polythiophene derivatives show very efficient charge separation following photoexcitation [146-148]. Two-layer diodes of C60 and MEH-PPV were reported initially to show poor efficiencies [149], but photovoltaic efficiencies (short circuit) up to 9% have now been obtained for PPV/ Ceo diodes of the type shown in Fig. 29.20 [150]. Charac-... 

This review is directed at the alternative strategy the utilization of asymmetric coupling of asymmetric monomers in order to achieve regioregular HT coupled structures of polythiophene derivatives. 

The structural variation can be measured as against a perfect crystal lattice where the polythiophene backbones satisfy the translational symmetry along the chain direction and form the herringbone structure spreading two-dimensionally perpendicular to that direction. In this respect polythiophene derivatives, especially PATs, provide a variety of peculiar structures. Examples include a bundled structure in which the rodlike polymer chains form nearly the face-to-face configuration. Helical and superhelical structures can be noted as well. The polymers having chiral side chains even exhibit stereomutation associated with the main-chain chirality. 

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