New syntheses and spectral properties of diazepine fluorescent dyes with non-planar molecular structure

Two types of new diazepine fluorescent dyes were synthesized by the condensation of N-(4-substituted-4-oxo-2-buten-2-yl) diaminomaleonitrile and 2,3-dicyano-6H-1,4-diazepines with an arylaldehyde. Regioselective condensation reaction are observed and their reactivities are evaluated from their optimized molecular structures obtained by means of the ab initio molecular orbital calculation methods. Substituent effects of the donor moiety to absorption and fluorescent properties in solution were correlated with chromophoric systems with regard to the non-planar diazepine moiety. A strong intramolecular charge-transfer chromophoric system of dyes are confirmed and its large Stokes shift of over 100 nm resulted in emission of red fluorescence. These dyes are of current interest as a red light emitter for electroluminescence devices.