K.-U. Gaudl

Synthesis and structural characterization of alkyl oligothiophenes—the first isomerically pure dialkylsexithiophene

Regioselective bromination of alkylated bi-and ter-thiophenes affords key building blocks for the synthesis of higher, isomerically pure alkyl oligothiophenes. For all new compounds, unequivocal structural assignment is based on a detailed analysis of the fully coupled 13C, 1H NMR spectra.

Third generation of conducting polymers: Spectroelectrochemical investigations on viologen functionalized poly (3‐alkylthiophenes)

Results of in situ electron spin resonance, optical absorption, and Fourier transform infrared spectroscopic studies during electrochemical doping and undoping processes of viologen functionalized poly (3‐alkylthiophenes) are reported. Effects of the functional group on the electronic properties of the polythiophene backbone in its conducting state are observed resulting in localization of the charge carriers. Radicals on the viologen side group show hyperfine structured electron spin resonance signals indicating a rapid motional averaging of anisotropic electron‐nuclear couplings. Experimental results are discussed by comparison with other substituted polythiophenes in terms of conformational effects of the acceptor group on the conducting polymer backbone. A structural model with counterion complexation between polythiophene backbone and the viologen functional unit is presented.

New functionalized polythiophenes

Abstract The development of a series of new functionalized polythiophenes prepared by electropolymerization is described. The corresponding monomers were synthesized starting with ω-haloalkyl substituted mono-, bi- and terthiophenes which were subsequently further reacted to yield viologens and ferrocenes. The characterization of both monomers and polymers revealed a dependence of the properties on the type of heterocyclic unit involved in the monomer, on the steric and electronic influence of the functional group and on the ratio of functional groups per monomeric units.

Evidence for counterion complexation in the conducting state of viologen-functionalized poly (3-alkylthiophenes)

Abstract Results of in situ electron-paramagnetic resonance, optical absorption, Fourier-transform-infrared spectroscopy during electro-chemical doping and undoping processes, as well as solid-state 1 H NMR relaxation studies in the doped and undoped form of viologen-functionalized poly (3-alkylthiophenes) are reported. Effects of the viologen side group on the electronic properties of the polythiophene backbone in its conducting state are observed. Experimental results are discussed in terms of localization of charge carriers on the polythiophene backbone. Considering the NMR relaxation data, we propose a structural model with counterion complexation between the polymer backbone and the viologen side group.

Polythiophenes Functionalized with Redoxactive Groups

A series of functionalized alkyl(oligo)thiophenes bearing covalently linked donor and acceptor groups were synthesized. Their electrochemical polymerization led to various new conducting polymers which besides their electrical conductivity incorporate the specific redoxactivity of viologen-, ferrocene-, quinone- and metal-complexed 2,2’-bipyridine groups. Unexpected effects concerning the interplay of the functional group and the polymeric backbone were observed and rationalized.

In Situ Spectroscopic Studies on Viologen Functionalized Poly(3-Alkylthiophenes) During Electrochemical Redox Processes

In this work we present results of in situ optical absorption, electron spin resonance, as well as Fourier transform infrared spectroscopic studies during electrochemical doping and undoping processes of viologen functionalized poly(3-alkylthiophenes). Two reduction processes of the viologen side group in addition to the oxidation process of the polythiophene backbone are observed. The spectroscopic data indicate influences of the viologen side group on the electronic properties of polythiophene backbone. Radicals on the viologen side group show hyperfine structured electron spin resonance signals indicating a rapid motional averaging of anisotropic electron-nuclear couplings.

A Solid State 1 H NMR Study of Motion in Polythiophenes

We have investigated, via solid state 1H NME, the motional dynamics in three classes of polythiophenes - polythiophene, poly (3-alkyl thiophene), and viologen functionalized poly (3-alkylthiophene). Evidence for backbone stiffening of polythiophene upon doping is presented. Two distinct types of sidechain motion are identified in the substituted polythiophenes and the effect of the electron acceptor, viojogen, on these motions in both the doped and undoped states is discussed.