A new ratiometric and colorimetric fluorescent Th4+ probe under extreme acidity and cell imaging

It is always a significant challenge to develop a probe for Th 4+ in the environment and in vivo under extreme acidity conditions, especially on real-time in the field. Herein, a new Th 4+ fluorescent probe N1′,N2′-bis((3-hydroxytetrastyrene-2yl)methylene malonohydrazide ( BH-TPE ) was designed and studied. It could realize to detect Th 4+ in a ratiometric way, which showed relative strong blue fluorescence at 450 nm and yellow-green fluorescence at 522 nm in the absence or present of Th 4+ , respectively, with good selectivity and sensitivity under extreme acidity environment. And the value of I 522 /I 450 of the probe had good linear relationship with Th 4+ ion concentration in the range of 0–10 μM and the low detection limit 2 × 10 −8  M. Meanwhile, it could monitor Th 4+ ion by “naked eye” in the field on real-time due to the BH-TPE solution changed from colorless to light green with the increase of Th 4+ . Moreover, the possible fluorescent mechanism was proposed. Most importantly, the viability of BH-TPE to Th 4+ ion was successfully applied to live cell imaging and environmental sample.