Pyrrolodiazine derivatives as blue organic luminophores: synthesis and properties. Part 3

A fast, efficient, general and environmentally friendly method for preparation of highly fluorescent derivatives containing the pyrrolodiazine moiety using microwave (MW) irradiation, in liquid phase, is reported. Under MW irradiation the yields are much higher, sometimes substantially (by almost double) and, the amount of solvent used is at least 5-fold less. The pyrrolopyridazine (PP) derivatives are very intense blue emitters and have high quantum yields (up to 90%) while pyrrolophthalazine (PHP) compounds are still intense blue emitters but the quantum yield is negligible. A certain influence of the substituents concerning fluorescence was found, those ones at the 7 position being crucial for fluorescence. The number of the substituents from the pyrrolo ring seems not to play an important role in regard with the fluorescence but, with an increasing number of substituents a certain hypsochromic shift in the absorption spectra was found.