Ratiometric fluorescent probes for ClO− and in vivo applications

• Two 1,8-naphthalimide derivatives were synthesized as ratiometric fluorescent probes for ClO−.
• These two probes exhibit highly selective recognition of ClO− over other analytes.
• The potential application of probe to bioimaging was also illustrated.

Newly synthesized 1,8-naphthalimide derivatives, 1 and 2, are found to detect specifically ClO− in presence of large excess of other competing ions with associated changes in their optical and fluorescence spectral behavior. These spectral changes are significant enough in the visible region of the spectrum and thus, allow the visual detection. The detection limit is low as 10−8 M. 1 and 2 could be used as ratiometric sensors for detection of ClO− based on the intramolecular charge transfer (ICT) process involving the donor 1,8-naphthalimide and the acceptor indolium iodide. Further, confocal laser microscopic studies confirmed that the probe 1 could also be used as imaging probe for detection of ClO− in HepG2 cells.

The sensor that displayed ratiometric response toward hypochlorous acid with fluorescence color change from red to green after reaction with ClO−, was characterized using NMR and mass spectroscopy. Its potential application to bioimaging was also illustrated.Figure optionsDownload as PowerPoint slide