Naphthalimide-Based Turn-On Fluorosensor for Aqueous Sulfide Ions for Staining in Living Cells

摘要

A newly synthesized and characterized naphthalimide derivative (L1) acts as a highly sensitive chemosensor for aqueous sulfide ions in water/DMSO (3:1, v/v) medium as L~1 offers distinctive reactive properties toward aqueous sulfide ions to be converted to L~(1A) of potential turn-on fluorescent properties over other competitive anions. Gradual addition of aqueous sulfide ions led to the formation of in situ L~(1A) compound which showed a single point fluorescence enhancement based on intramolecular charge transfer (ICT). To establish this new interesting pathway in favor of ICT for sensing sulfide ions, the detailed spectroscopic studies of other three similar type new 1,8-naphthalimide based organic probes (L~2, L~3 and L~4) duly structurally characterized including theoretical (DFT) studies have been carried out systematically. The probe (L~1) detects aqueous sulfide ions as low as 2.4 mM in at biological pH within a very short responsive time (15-20 s) and this non-cytotoxic the probe, L1 is also useful in acquiring the fluorescent image of the distribution of sulfide ions in living cells using fluorescence microscope.