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Synthesis and Electronic Properties of Monodisperse Oligophenothiazines
Author(s) -
Sailer Markus,
Franz Adam W.,
Müller Thomas J. J.
Publication year - 2008
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.200701341
Subject(s) - borylation , dispersity , chemistry , suzuki reaction , oligomer , random hexamer , cyclic voltammetry , fluorescence , absorption (acoustics) , absorption spectroscopy , photochemistry , polymer chemistry , crystallography , materials science , organic chemistry , alkyl , physics , electrode , quantum mechanics , aryl , electrochemistry , composite material
Starting from N ‐hexylphenothiazine, a versatile construction kit of brominated and borylated phenothiazines can be easily prepared by a sequence of bromination, bromo–lithium exchange/borylation, and Suzuki coupling. Subsequent Suzuki arylation of the building blocks gives soluble, monodisperse, and structurally well defined oligophenothiazines in good yields. The molecular weights at the peak maximum ( M p ), obtained by GPC ( g el p ermeation c hromatography), and the actual molecular weights of the oligomer series, obtained by mass spectrometry, show excellent correlation. A QM/MM conformational analysis for the complete series reveals that the obvious butterfly‐shaped phenothiazine structure multiplies and significantly reduces the hydrodynamic volume of the oligomers. The electronic properties (absorption and emission spectroscopy and cyclic voltammetry) give reasonable correlations with the chain length. With regard to the emission maxima, the effective conjugation length is already reached with the hexamer. Oligophenothiazines are highly fluorescent, with high fluorescence quantum yields, and are simultaneously highly electroactive, with low oxidation potentials.