Fluorescein‐Based ‘‘Turn On’’ Fluorescence Detection of Zn ²⁺ and Its Applications in Imaging of Zn ²⁺ in Apoptotic Cells

Abstract

Abstract Fluorescein dye bearing imidazole has been designed and synthesized as an effective colorimetric and ‘‘turn on’’ fluorescent sensor for Zn 2+ . The probe FI‐1 shows selective and dramatic colour change from colourless to yellow and fluorescence turn‐on response for Zn 2+ with greater sensitivity. 1 H NMR titration experiments confirms that the binding of Zn 2+ ions leads to the spirolactam ring opening that causes change in absorbance and fluorescence. Density functional theory calculations also support the observed photophysical changes. The applicability of the probe for Zn 2+ detection was shown by the live cell imaging in HeLa cells. Further the probe utilized for imaging of Zn 2+ ions liberated during apoptosis.