A Zn²⁺ Fluorescent Sensor Derived from 2-(Pyridin-2-yl)benzoimidazole with Ratiometric Sensing Potential

A fluorescent Zn²⁺ sensor based on the 2-(2′-pyridinyl)benzoimidazole (2-PBI) fluorophore has been devised by incorporation with a Zn²⁺ ionophore, bis(pyridin-2-ylmethyl)amine. The sensor (PBITA) demonstrates a Zn²⁺-specific emission shift and enhancement with a 1:1 binding ratio. Due to the Zn²⁺-induced coplanation of 2-PBI via reversion/rotation, PBITA is shown to behave as a ratiometric sensor. The intracellular Zn²⁺ imaging ability of the sensor has been tested in HeLa cells using a confocal microscope.