A Simple Benzimidazole Based Fluorescent Sensor for Ratiometric Recognition of Zn2+ in Water

A phenylbenzimidazole derivatized sensor (L) that behaves as a ratiometric fluorescent receptor for Zn2+ in water has been described. In HEPES buffer at pH 7.4, sensor L displays a weak fluorescence emission band at 367 nm. Upon addition of Zn2+, the emission intensity at 367 nm is decreased, concomitantly, a new emission band centered at 426 nm is developed, thus facilitates a ratiometric Zn2+ sensing behavior. Sensor L binds Zn2+ through a 1:1 binding stoichiometry with high selectivity over other metal cations. Sensor L displays a linear response to Zn2+ concentration from 0 to 6.0 x 10(-5) M, sensor L also exhibits high sensitivity to Zn2+ with a detection limit of 3.31 x 10(-7) M.