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Molecules 2007, 12(4), 723-734; doi:10.3390/12040723

Multi-step Redox Systems with NIR-Fluorescence Based on 4H-Imidazoles

 and *
Institute of Organic and Makromolecular Chemistry, Friedrich-Schiller University D-07743 Jena, Humboldtstr. 10, Germany
* Author to whom correspondence should be addressed.
Received: 22 March 2007 / Revised: 29 March 2007 / Accepted: 29 March 2007 / Published: 5 April 2007
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A new class of 4H-imidazoles was synthesized starting from fused-ring aromatic dinitriles. Strong bathochromic shifts of the longest wavelength absorptions were observed in the corresponding UV/vis spectra due to a conversion of the merocyanine chromophores into cyanines/(aza)oxonoles upon protonation/deprotonation of the 4H-imidazoles. Novel boratetraazapentalenes were synthesized via a cyclization reaction with boron trifluoride. These mesoionic species bearing a cyanine chromophore not only show NIR-fluorescence, they also participate as part of a quasi-reversible multi-step redox system. Large calculated semiquinone formation constants KSEM (3x1010 to 5x1011) indicate a high thermodynamic stability of the corresponding radical anions (SEM).
Keywords: 4H-Imidazoles; boratetraazapentalenes; multi-step redoxsystems; NIR-fluorescence 4H-Imidazoles; boratetraazapentalenes; multi-step redoxsystems; NIR-fluorescence
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Matschke, M.; Beckert, R. Multi-step Redox Systems with NIR-Fluorescence Based on 4H-Imidazoles. Molecules 2007, 12, 723-734.

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