Green fluorescence pyrene-based dye as a new π-extended system: Synthesis, photophysical and theoretical studies

The introduction of phenylethynyl groups on to the 4-(pyren-1-yl)butanoic acid core structure using a copper-free Sonogashira coupling resulted in the formation of a highly efficient green light emitting material. The new photoluminescente pyrene derivative has a large fluorescence quantum yield of 0.72 in DMSO (τ = 1.89 ns) and a small solvatochromic effect. The structure of the new pyrene derivative was investigated by density functional theory (DFT) calculations. The results corroborate the participation of the phenylethynyl groups as part of the structure of both the HOMO and the LUMO orbitals, thus explaining the red shifted emission, relative to pyrene, into the visible region as a consequence of the extended π-conjugation.