Blue-red emitting 2,12-disubstituted [5]helicenes for high fluorescence efficiency and sensing application

We report photochemical synthesis of two new fluorene and carbazole-based 2,12-disubstituted [5]helicenes namely FLU-HEL and CBZ-HEL respectively. Both FLU-HEL and CBZ-HEL exhibit very intense fluorescence property in solution as well as solid state. The fluorescence quantum yield (Φf) = 27 % and 30 % and life time ⟨τf⟩=9.7 ns and 4.2 ns were observe for both [5]helicenes, respectively. Also, both the [5]helicene dyes have shown very good sensing properties towards Fe3+ transition metal ion than other transition metal ions. We have also explored the feasibility of these compounds for security applications.