SYNTHESES AND CHARACTERIZATION OF NEW STYRYL FLUORESCENT DYES FROM DAMN .2.

2,3-Bis(bromomethyl)-5,6-dicyanopyrazine (3) can be prepared more read ily by the condensation of DAMN (1) and 1,4-dibromobutane-2,3-dione (2 ) than by direct bromination of 2,3-dimethyl-5,6-dicyanopyrazine. The Wittig reaction of 3 with arylaldehydes gave a new type of fluorescent styryl dyes (6-8). These styryl dyes have extended pi-conjugation sys tems and strong intramolecular charge-transfer chromophoric systems. T hey have strong fluorescence in solution and some have fluorescence ev en in the solid state, which is very important to evaluate their elect roluminescence (EL) property as the emitter for EL devices. Calculatio n of excitation energies using the PPP-MO method, and optimization of their structures using the MOPAC with the PM 3 method were conducted, and their spectral properties are discussed to correlate their functio nalities with chemical structures. (C) 1997 Elsevier Science Ltd.