Synthesis and photophysical properties of novel butterfly-shaped blue emitters based on pyrene

Using 1,3,5,9-tetrabromo-7-tert-butylpyrene as the bromide precursor, a series of novel butterfly-shaped 1,3,5,9-tetraaryl substituted pyrene derivatives were synthesized by the Suzuki-Miyaura cross-coupling reaction. Their thermal, photophysical, electrochemical and related properties were systematically investigated. All compounds were found to exhibit high thermal stabilities with decomposition temperatures (Td) of up to 300 °C. All compounds show highly blue fluorescence emissions in the spectral region of 412-469 nm in solution (Φf: 0.45-0.92) and 410-470 nm in the solid- state (Φf: 0.48-0.75). It is noteworthy that these butterfly-shaped pyrenes 4 possess low-lying HOMO levels ranging from -4.76 to -5.93 eV, which make them promising candidates in OLED applications.