An effective long-wavelength fluorescent sensor for Cu2+ based on dibenzylidenehydrazine-bridged biphenylacrylonitrile.

Although numerous fluorescence sensors for Cu2+ have been presented, a long-wavelength sensor in aqueous media has rarely been reported as expected due to practical application requirements. In this work, a novel AIE molecule (DHBB) containing two biphenylacrylonitrile units bridged by dibenzylidenehydrazine was prepared. It possessed the merits of long-wavelength emission, good emission in aqueous media, and multiple functional groups for binding Cu2+. It exhibited good sensing selectivity for Cu2+ among all kinds of tested metal ions. The detection limit was as low as 1.08 × 10-7 M. The sensing mechanism was clarified as 1:1 stoichiometric ratio based on the binding cooperation of O and N functional groups of DHBB. The selective sensing ability for Cu2+ remained stable at pH = 5-9 and was influenced little by other metal ions. The Cu2+ sensing ability of DHBB was applied in real samples with 96% recovery rate. The bio-imaging experiment of living cells suggested that DHBB possessed not only good bio-imaging performance but also sensing ability for Cu2+ in living environments. This work suggested the good application prospect of DHBB to sense Cu2+ in real samples and living environment.