Highly efficient and selective red-emitting Ca²⁺ probe based on a BODIPY fluorophore

A red-emitting Ca²⁺ probe based on difluoro-boron-dipyrromethene (BODIPY) fluorophore and 1,2-bis(o-aminophenoxy)ethane-N,N,-N′,N'-tetra acetic acid (BAPTA) moiety was designed and synthesized. Four electron-donating 4-methoxyphenyl groups were introduced on BODIPY to make the emission of probe more bathochromic-shifted. Upon Ca²⁺ binding, the probe exhibits a significant increase of red fluorescence intensity (λ_max = 631 nm, Φ_F = 0.18), an excellent luminescence ON/OFF ratio (43-fold) and a detection limit of 39 μM. Furthermore, this probe shows desirable sensitivity and selectivity for Ca²⁺ over other metal ions, which could be potentially applied for Ca²⁺ detection.