Synthese und Charakterisierung von Stilbazoliumfarbstoffen mit mesoionischer 1,2-Diaziniumstruktur

Synthesis and Characterization of Stilbazolium Dyes with Mesoionic 1,2-Diazinium Structure Pyridazinium salts of typ 1 react with substituted aromatic and heteroaromatic aldehydes 2a , e–h , 8a–c and trans-p-dimethylamino-cinnamaldehyde 3a to the charge transfer dyes 4a–h , 5a–d , 9a–c . They absorb in the range between 380 and 660°nm. The dehydratisation of the aldoxime group in 4, 5 to the nitril group under formation of 6 , 7a–d causes a bathochromic shift of the absorption band up to 110 nm. The UV-VIS data are discussed dependent on the structure of the dyes.