Super-quenching: Multiple migration channels of excitons cause 'area quenching'

Fluorescent conjugated polymers are widely used for trace detection of explosives due to their super-quenching effect. In this work, a hyper-branched conjugated polymer P2 and a linear conjugated polymer P1 were synthesized. Compared with P1, P2 showed the superior sensitivity toward 2,4,6-trinitrophenol (PA). The Stern-Volmer constants (Ksv) of P2 (1.56 × 104 M−1) was 2.7 times higher than that of P1 (0.57 × 104 M−1), and the LODs to PA of P2 (8.8 μM) was 3.2 times lower than that of P1 (24 μM). These data indicated the enhanced super-quenching effect in P2. Due to the electrons transfer among the conjugated backbone of polymer, the super-quenching effect of P1 with one-dimensional (1D) configuration may be defined as “length quenching”, while that of P2 with two-dimensional (2D) configuration can be defined as “Area quenching”. The 2D conjugation nature of P2 provided multi migration channel for excitons, which resulted in the remarkably enhanced super-quenching.