Imidazole as a Donor/Acceptor Unit in Charge‐Transfer Chromophores with Extended π‐Linkers |
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Authors: | Prof Jiří Kulhánek Prof Filip Bureš Prof Oldřich Pytela Dr Tomáš Mikysek Prof Jiří Ludvík |
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Institution: | 1. Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, 53210 (Czech Republic), Fax: (+420)?46‐603‐7068;2. Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, 53210 (Czech Republic);3. J. Heyrovsky Institute of Physical Chemistry, Academy of Science of the Czech Republic, v.v.i. Dolej?kova 3, Prague 8, 18223 (Czech Republic) |
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Abstract: | Eleven new, stable, push–pull systems that feature 4,5‐bis4‐(N,N‐dimethylamino)phenyl]imidazole and 4,5‐dicyanoimidazole as the donor and acceptor moieties and the systematically extended and varied π‐linker were prepared and investigated. Evaluation of the measured UV/Vis spectra, electrochemical data (cyclic voltammetry (CV), rotating‐disc voltammetry (RDV), and polarography) and calculated β and γ polarizabilities showed efficient charge transfer (CT) in biimidazole‐type chromophores. Push–pull system 27 , which features a planar thiophene‐derived π‐linker, was revealed to be the most efficient chromophore within the studied series. This chromophore possessed the most bathochromically shifted CT band, the lowest electrochemical gap, and highest β and γ polarizabilities. The CT transition was most significantly affected by structural features such as π‐linker length, planarity, conjugating arrangement, and the presence of olefinic/acetylenic or 1,4‐phenylene/thiophene subunits in the π‐linker. |
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Keywords: | charge transfer conjugation donor– acceptor systems electrochemistry imidazoles |
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