Oligothiophenes end-capped

Bauerle P, Segelbacher U, Maier A, Mehring M (1993) Electronic-structure of monomeric and dimeric cation radicals in end-capped oligothiophenes. J Am Chem Soc 115 10217... 

Thiol end-capped oligothiophenes 105a-c were used to form the SAMs between the electrodes. A series of distinct periodic steps in the conductance was observed for all samples at low temperature (<100 K). These features were suggested to originate from vibrational modes in the molecules. A (weakly coupled) gate potential could be applied to the molecular junction, which shifted the step position in the I(V) curves but not the step widths. This observation was taken as an indication that only a single molecule was electrically active in the molecular junction. 

CNDO complete neglect of differential overlap ECnT end-capped oligothiophene (compare... 

The group of Umbach, studies the performance of devices with end-capped oligothiophenes [312,314]. The substrate is again ITO, electrodes are made from Mg, Al, or In or, more recently, from Ca, which leads to the highest quantum efficiency [320] (compare Table 13.10). 

The IR and Raman spectra of thiophene, 2,2 -bithienyl and of the cycloalkane end-capped oligothiophenes has been studied and the results compared with theoretical calculations at the ab initio SCF level <93JST(298)65>. The scaled theoretical and experimental vibrational frequencies and theoretical IR and Raman intensities as well as their assignments for the above compounds have been discussed. 

P. Bauerle, End-capped oligothiophenes - new model compounds for polythiophenes, Adv. Mater., 4, 102-107... 

C. Zhao, Y. Zhang, C. Wang, L. Rothberg and M. K. Ng, Synthesis of homopolymer containing diphenyl end-capped oligothiophene co-oligomer unit in the side-chain, Org. Lett., 8, 1585-1588 (2006). 

Figure 8.5 Comparison between the B3LYP/6-31 G(d,p) theoretical infrared spectra of (a) diprotonated a,a -bis(aminomethyl)terthiophene, (b) unprotonated trimer and (c) experimental infrared spectrum of a,a -bis(aminomethyl)terthiophene in neutral form. Experimental spectrum obtained on powdered samples in pressed KBr pellets. Reprinted with permission from V. Hernandez, H. Muguruma, S. Hotta, J. Casado and ). T. Lopez Navarrete, A combined spectroscopic and theoretical study of a series of aminomethyl end-capped oligothiophenes with potential applications in thin film devices, J. Phys. Chem. A, 104, 735-740 (2000), Copyright 2000 American Chemical Society...

BSuerle and co-workers described the synthesis and characterization of a complete series of end-capped oligothiophenes ECnT, up to the heptamer (Scheme 9.21) [22, 101, 111]. Their strategy relies on the use of 4,5,6,7-tetrahydrobenzo[fc]thiophene at both end of the oUgothiophene. This type of functionalization has two main consequences. Eirst, the substitution at the terminal a-positions and that at the outermost P-positions prevents the a-oT coupling and limits the a-f) coupling of the radical cation, thus making possible the characterization of the various oxidation state of the oligomers. Second, the introduction of substituents at the [ -positions confers enhanced solubility on the molecules. 

Mixing of thiophene with the fluorine ring results in enhanced ambient and radiation stability. Fluorene end-capped oligothiophenes with n = 1 -4 have been synthesized and exhibit field effect mobilities up to 0.1 cm s and /on foff up to 10 for 42a (Figure 16.24) [103]. Locklin et al. [104] investigated the... 

Procter and collaborators reported the synthesis of benzo[Z)]-carbazole end-capped oligothiophene organic semi-conductors using a tag intro-duction-cyclisation - tag removal-cyclisation approach. After the... 

Scheme 28 Procter s phase-tag assisted synthesis of benzo[fa]-carbazole end-capped oligothiophenes.

The peculiar cyclic voltammetry and ESR behavior of PT has been satisfactorily explained by studying end-capped oligothiophenes (MejTn), 3, in the solid state [174]. 

Fig. 6. Chemical structures of a-oligothiophenes (a) unsubstituted oligothiophenes (b) dimethyloligothiophenes (Me CH3) (c) and (d) partly /3-substituted sexithiophenes (R C10H21, C12H25) (e) partly 8-substituted dodecamer (R C10H21, C12H25) (f) partly /3-substituted disilylsexithio-phene (R -C4H9) (g) end-capped oligothiophenes.

With respect to their properties in solution and the solid state, the model character and their applications as new materials, the end-capped oligothiophenes ECnT seem to be one of the best investigated series up to now. Due to their defined character, their elfective purification methods and controllable processability by vacuum evaporation highly pure materials are obtained. 

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