Synthesis of new porphyrins with dicyanopyrazine moiety and their optical properties

5,10,15,20-Tetra[5-{2-(4-alkoxyphenyl)-ethenyl}-6-{2-phenyl-ethenyl}-2,3-dicyano-pyrazino]-porphyrin (5) was prepared by the condensation reaction of pyrrole and a bis-styryl derivative (4) containing 2,3-dicyanopyrazine. The existence of a strong intramolecular charge-transfer chromophoric system was confirmed for dyes 5, and its large Stokes shift of over 200 nm resulted in the emission of red fluorescence. The chromophoric systems of these dyes were studied from the viewpoint of the protonation and deprotonation effects on their absorption and fluorescence spectra in solution. (c) 2005 Elsevier Ltd. All rights reserved.