Imidazole as a donor/acceptor unit in charge-transfer chromophores with extended π-linkers

Jiří Kulhánek; Filip Bureš; Oldřich Pytela; Tomáš Mikysek; Jiří Ludvík

doi:10.1002/asia.201100097

Imidazole as a donor/acceptor unit in charge-transfer chromophores with extended π-linkers

Chem Asian J. 2011 Jun 6;6(6):1604-12. doi: 10.1002/asia.201100097. Epub 2011 May 19.

Authors

Jiří Kulhánek¹, Filip Bureš, Oldřich Pytela, Tomáš Mikysek, Jiří Ludvík

Affiliation

¹ Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, 53210, Czech Republic.

PMID: 21598401
DOI: 10.1002/asia.201100097

Abstract

Eleven new, stable, push-pull systems that feature 4,5-bis[4-(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.