Synthesis and characterization of unsymmetrical phenylene–ethynylene trimers and tetramers with different chromophores as blue-light-emitters

A series of highly fluorescent p-phenylene–ethynylene π-conjugated oligomers (trimers and tetramers) with different chromophore substituents have been synthesized stepwise under oxygen-free Sonogashira conditions. The emission wavelengths range from 400 to 455 nm for the series. All four trimers and tetramers have visible blue emission under sunlight especially for the case of the pyrene-substituted trimer and tetramer. All oligomers also exhibit very high quantum yields (0.9–1.1), which suggest that these types of compounds could be used as blue-light-emitters.