کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5225490 | 1383548 | 2008 | 7 صفحه PDF | دانلود رایگان |
A series of bichromophores consisting of a 'classical' chromophore and 4H-imidazoles were synthesized starting from appropriate cyano and carboxy functionalized systems. In their UV-vis spectra, an additive absorption of both chromophores was detected making them wide range-absorbing dyes. In addition, new properties as redox activity, pH-switchability and metal-chelating substructures are newly introduced into the molecules. In order to achieve more bathochromic absorbing systems, the chromophore of 4H-imidazoles was extended. The 4H-imidazo-[1,2-a]-pyridines, which are easily accessible by cyclization of 2-aminopyridines with bis-imidoylchlorides, show long wavelength absorptions up to 616Â nm. Their reduction reversibly yields yellow, blue fluorescent 1-azaindolizines. In contrast to leuco-forms of 4H-imidazoles, these reduction products show a high stability towards oxygen and could only be reoxidized to their starting materials by oxidation agents, such as DDQ.
Journal: Tetrahedron - Volume 64, Issue 33, 11 August 2008, Pages 7815-7821