Synthesis and characterization of X-shaped oligo(para-phenylene) derivatives functionalized with fluorene ethynylene

A series of linear and X-shaped oligo(para-phenylene) derivatives functionalized with fluorene ethynylenes 1, 3 and 4 were synthesized through sequent Sonogashira coupling and Suzuki–Miyaura reaction in high yield. The electron-donating group –OCH3 and electron-withdrawing counterparts –CF3 were introduced to tune the spectra properties of compounds 3 and 4. The detail investigation of their photophysical properties in solution and film indicated that the introduction of both –OCH3 and –CF3 makes maximum emission distinct red-shift in comparison with parent compound 1, but the latter more prominently.