A benzo-15-crown-5-modifying ratiometric-absorption and fluorescent OFF–ON chemosensor for Cu2 +

• A new benzo-15-crown-5-modified Schiff sensor has been first facilely synthesized.
• The employment of benzo-15-crown-5 moiety in FBC as additional binding platform for Cu2 + not only amplifies the fluorescent enhancement of FBC but also increases its binding selectivity and affinity to Cu2 + over other metal ions tested.
• The benzo-15-crown-5-modified fluorene sensor displays highly sensitive ratiometric-absorption and fluorescence OFF-ON response to Cu2 +.

One new benzo-15-crown-5-modifying fluorene Schiff base (FBC), together with the CN-linked fluorene-3,4-dimethoxybenzene (FBDMO) and fluorene-benzene (FB) references, has been designed and facilely synthesized. The binding of Cu2 + with nitrogen atom of CN moiety in these three compounds can inhibit the photo-induced electronic transition process and induce the ratiometric-absorption and fluorescent OFF–ON response to Cu2 +. Whereas the employment of benzo-15-crown-5 moiety in FBC as additional binding platform for Cu2 + not only amplifies the fluorescent enhancement of FBCvia preventing the isomerization of CN moiety, but also endows this compound high selectivity and rapid response towards Cu2 + over the references FB and FBDMO. These results render FBC highly sensitive ratiometric-absorption and fluorescent OFF–ON detecting potential for Cu2 + with the detection limit of 3.91 × 10− 6 M.

One new benzo-15-crown-5-modified fluorene Schiff base (FBC), together with the CN-linked fluorene-3,4-dimethoxybenzene (FBDMO) and fluorene-benzene (FB) references, has been designed and facilely synthesized. The binding of Cu2 + with nitrogen atom of CN moiety in these three compound can inhibit the photo-induced electronic transition process and induce the ratiometric-absorption and fluorescent OFF–ON response to Cu2 +. Whereas the employment of benzo-15-crown-5 moiety in FBC as additional binding platform for Cu2 + not only amplifies the fluorescent enhancement of FBCvia preventing the isomerization of CN moiety, but also endows this compound the efficient selectivity and binding affinity to Cu2 + over the references FB and FBDMO. These results render FBC highly sensitive ratiometric-absorption and fluorescent OFF–ON detecting potential for Cu2 + with the detection limit of 3.91 × 10− 6 M.Figure optionsDownload as PowerPoint slide