LAUSR

Abstract Novel 5,6,5,6-tetracyclic pyrazine/pyrrole-fused unsymmetric bis(BF2) fluorescent dyes (BOPYPYs) were obtained by reaction of pyrrole-2-carboxaldehyde with 1-(pyrazin-2-yl)hydrazine in the presence of Et3N-BF3·Et2O for the first time. The absorption maxima of pyrazine-fused BOPYPY are obviously bathochromic shifts, in contrast to those of the reported BOPPY, indicating that the discrepant substitute groups between pyridine and pyrazine result in the remarkable wavelength difference. The new series of BOPYPYs possess high molar extinction coefficients, high fluorescence quantum yields, and larger Stokes shifts. A Knoevenagel reaction of BOPYPY with 4-dimethylaminobenzaldehyde smoothly produced the dye with the extension of π-conjugation. Dimethylamino-containing BOPYPY as a pH-responsive fluorescent sensor could detect pH value.