Single excited state intramolecular proton transfer (ESIPT) chemodosimeter based on rhodol for both Hg2+ and OCl-: ratiometric detection with live-cell imaging

For ratiometric, fluorogenic and naked eye detection of the environmentally and biologically important ions Hg2+ and OCl- in one platform, a 2-(2'-hydroxyphenyl)-benzothiazole (HBT) inserted thiolactam containing a new rhodol system, spirothiolactamized benzothiazole substituted N,N-diethylrhodol (STBR), is designed and synthesized. We can detect Hg2+ and OCl- in solutions by a simple, easy-to-synthesize practical ratiometric chemodosimeter with two different modes of reactions with a low detection limit. The observed color in the presence of Hg2+ or OCl- may arise from the reaction of Hg2+ or OCl- with STBR - the thiolactam moiety is broken and it helps to achieve maximum pi-pi* conjugation which results in a brilliant red fluorescence. From H-1-NMR and ESI-MS data, it is clear that the modes of the reaction for Hg2+ and OCl- are different. Test strips are also prepared to observe color changes. The sensing phenomena are fruitfully applied for live-cell imaging in Saccharomyces cerevisiae cells (from a short to long time range, 0 min to 120 min). The single crystal X-ray structure of the synthesised ESIPT rhodol moiety is also reported.