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Toward the peri ‐Pentacene Framework
Author(s) -
Zöphel Lukas,
Berger Reinhard,
Gao Peng,
Enkelmann Volker,
Baumgarten Martin,
Wagner Manfred,
Müllen Klaus
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201302859
Subject(s) - pentacene , protonation , chemistry , cyclic voltammetry , reactivity (psychology) , spectroscopy , pyrene , photochemistry , nuclear magnetic resonance spectroscopy , ion , organic chemistry , electrode , electrochemistry , medicine , physics , alternative medicine , quantum mechanics , thin film transistor , pathology
Based on modern pyrene chemistry, a new route toward the synthesis of the peri ‐pentacene framework was developed. Firstly, the tetraketo form as stable precursor was targeted, because the fully aromatic peri ‐pentacene is predicted to suffer from high instability and reactivity. Therefore, a recently developed 4,5,9,10‐tetrafunctionalization of pyrene was utilized to build up a planar and a dragonfly‐shaped derivative in five steps, which only differ in the two outer bonds between the peripheral benzene rings. The planar tetraketone could only be dissolved in strong acids upon protonation, which limited the use of analytical methods. In contrast, the dragonfly‐shaped form showed excellent organosolubility. In‐depth investigation by NMR spectroscopy revealed co‐existence of atropo‐isomers in solution. The optical and electronic properties were analyzed by UV/Vis spectroscopy and cyclic voltammetry. To approach aromatic conjugation, stepwise reduction in solution by using tetrabutylammonium borohydride was carried out. Reduced species were studied by ESR and UV/Vis spectroscopy, as well as by MALDI‐TOF MS, confirming the formation of the radical anion.