Synthesis and Photophysical Properties of Polyfluorene With Dipicolylamine Groups on the Side Chain: Highly Selective and Sensitive Detection of Histidine

Two new polyfluorenes with dipicolylamine (DPA) pendant, PF‐TDPA and PF‐HDPA, are designed and synthesized by pre‐ and post‐functionalization, respectively. PF‐TDPA with a rigid side chain shows a selective fluorescence quenching upon the addition of Cu²⁺ in a mixture solution of tetrahydrofuran and 4‐(2‐hydroxyethyl)‐1‐piperazineethanesulfonic acid (HEPES) buffer. What is more, the PF‐TDPA/Cu²⁺ complex can selectively detect histidine over other amino acids with a fluorescence recovery. In contrast, PF‐HDPA with a flexible spacer exhibits a fluorescence quenching to Cu²⁺ but slightly fluorescence recovery after the addition of histidine. This indicates that the proper distance between the two DPA groups play an important role in the detection of histidine.