Polythiophene derivatives synthesis

A.-L. Ding, J. Pei, Y.-H. Lai, and W. Huang, Phenylene-functionalized polythiophene derivatives for light-emitting diodes their synthesis, characterization and properties, J. Mater. Chem., 11 3082-3086, 2001. 

First, the above-mentioned sensors have major drawbacks, as the detection and recognition event is a function of the nature and characteristics of the side chains, and the side chain functionalization of the CP requires advanced synthesis and extensive purification of numerous monomeric and polymeric derivatives. Second, this generation of sensors primarily employed optical absorption as the source for detection, resulting in lower sensitivity when compared with other sensing systems for biological processes. However, the use of fluorescence detection within these sensing systems could justify continued development. More recent examples include a fluorescent polythiophene derivative with carbohydrate functionalized side chains for the detection of different bacteria [15] and novel synthesis schemes for ligand-functionalization of polythiophenes [16]. 

H. Goto, X. Dai, H. Narihiro, K. Akagi, Synthesis of polythiophene derivatives bearing ferroelectric liquid crystalline substituents. Macromolecules 37, 2353-2362 (2004)... 

In Section 12.3, we describe the synthesis and thermal properties of FLC polythiophene derivatives, where fluorine-containing chiral LC groups are substituted in the 3-position of the thiophene ring [59-66]. Then, we report the optical properties and temperature dependence of the dielectric constant of the FLC polythienylene derivatives. 

R. Toyoshima, M. Narita, K. Akagi, H. Shirakawa, Synthesis and properties of polythiophene derivatives with liquid crystalline substituents, Synth. Met., 69, 289-290 (1995). 

Figure 19.1 Energy diagram of substituted PT 14b(PBET), 14c(PCBET)and9e(P30T). Reprinted with permission from S.-H. Ahn, M.-z. Czae, E.-R. Kim, H. Lee, S.-H. Han, J. Nob, M. Hara, Synthesis and characterization of soluble polythiophene derivatives containing electron-transporting moiety. Macromolecules, 34, 2522-2527 (2001). Copyright 2001 American Chemical Society.

J. Ohshita, K. Kimura, K.-H. Lee, A. Kunai, Y.-W. Kwak, E.-C. Son, Y. Kunugi, Synthesis of sihcon-bridged polythiophene derivatives and their apphcations to EL device materials, J. Polym. ScL, Part A Polym. Ghem., 45, 4588-4596 (2007). 

Ohshita J, Kimura K, Lee KH, Kunai A, Kwak YW, Son EC, Kunugi Y (2007) Synthesis of silicon-bridged polythiophene derivatives and their applications to EL device materials. J Polym Sci A Polym Chem 45 4588-4596... 

Polythiophene 6 provides a system closely related to polypyrrole 5, but in a certain respect it is easier to study. Like polypyrrole, polythiophene can be obtained by electrochemical polymerization of the heterocyclic monomer (Figure 11.2). It is also totally insoluble. The structure of polythiophene is, however, more easily controlled by synthesis. Several polythiophene derivatives merit mentioning. 

In this article we report the synthesis and electrochemical properties of the polymer derived from oxidation of X, poly(I), and the characteristics of a microelectrochemical transistor based on the polymer. Poly(I), which is formed by electrochemical oxidation of X, Equation 1, consists of a conducting polymer backbone, polythiophene. 

A modular and flexible approach to polythiophene sensors based on the polymerization of a thiophene-activated ester has been reported (Bernier et al. 2002). Subsequent reaction of the pol5mierized NHS ester with a variety of diamines permits the synthesis of sensors for different analytes from a common platform. For example, reaction of the NHS polymer with an aminomethyl-modified 15-crown-5 derivative yielded a polymer that underwent color changes in the presence of alkah cations (Fig. 12.14). 

Thiophene, pyrrole and their derivatives, in contrast to benzene, are easily oxidized electrochemically in common solvents and this has been a favourite route for their polymerization, because it allows in situ formation of thin films on electrode surfaces. Structure control in electrochemical polymerization is limited and the method is not well suited for preparing substantial amounts of polymer, so that there has been interest in chemical routes as an alternative. Most of the methods described above for synthesis of poly(p-phenylene) have been applied to synthesise polypyrrole and polythiophene, with varying success. 

The second method is the synthesis of copolymers or derivatives of a parent conjugated polymer with more desirable properties. This method is the more traditional one for making improvements to a polymer. It modifies the structure of the polymer to increase its processibility without compromising its conductivity or its optical properties. All attempts to do this on polyacetylene have failed as they always significantly reduced its conductivity. However, such attempts on polythiophenes and polypyrroles proved more fruitful. 

Summaries on the synthesis, properties, and uses of polythiophenes are included in two general reviews on poly thiophenes [259,260]. A synopsis of important aspects of polythiophenes are also included in several reviews on various aspects of conducting polymers [221-226], Cation radicals are the propagating species in both electrochemical and chemical oxidative polymerizations of thiophene and its derivatives. The polymer obtained by this method is linked primarily by a,a-linkages. However, other types of linkages (a,f3 and /3,/3) are present in varying amounts (Fig. 59). Substituted thiophene derivatives can couple in a head-to-tail or head-to-head manner. 

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