Through bond energy transfer (TBET)-based chemosensor with large Stokes shift for colorimetric and fluorogenic determination of Fe3+ in aqueous system and intracellular imaging application

Abstract

Chemosensor based on through-bond energy transfer (TBET) mechanism with triazaborolopyridinium (TBP) fluorophore as energy donor and rhodamine fluorophore as energy acceptor was designed, and its Fe3+ ion sensing properties were investigated in aqueous media. Prominent change of solution from yellow to pink and turn-on fluorescence emission was realized by employing Fe3+ selective recognition to form a Fe3+-rhodamine conjugate giving rise to emission at 590 nm with a large Stokes shift (210 nm) under the excitation at 380 nm. This sensor was highly selective and sensitive for distinguishing Fe3+ ions from other common cations. Interestingly, the achieved chemosensor exhibits the detection limits of 32 ppb and 14 ppb for chromogenic and fluorometric analysis, respectively, which are lower than the WHO and U.S. EPA permissible levels in drinking water. The reversible behavior of the Fe3+-sensor complex with the alternate additions of hydrazine and Fe3+ could establish the potential reusability. Moreover, the sensor has also been successfully applied for imaging the presence of Fe3+ ions in living cells.