Selective Modulation of Internal Charge Transfer and Photoinduced Electron Transfer Processes in N-Aryl-1,8-Naphthalimide Derivatives: Applications in Reaction-Based Fluorogenic Sensing of Sulfide.

Three reaction-based fluorescent probes based on two new naphthalimide platforms were developed for the detection of H2 S. A new approach in detecting H2 S by the reduction of an azide to a triazene intermediate in aqueous media is reported. Given their design features, these chemodosimeters provide useful insights into the relatively unexplored area of C0 spacers between receptor:reporter components. The N-aryl-1,8-naphthalimide platform features straightforward placement of the internal charge transfer and photoinduced electron transfer (PET) modulators on the same molecule. In the three examples presented, the N-aryl component proved to be an effective photophysical device as it allows the placement of a PET modulator at the strategically important and less explored imide position of 1,8-naphthalimides. These probes or dosimetric agents demonstrated good selectivity, two-signal response, and the desirable OFF-ON fluorescence response. By implementation of both the azido and nitro group as sulfide-reactive functionalities on the same chemosensory platform in probe SNAN-3, a much broader range of H2 S can be detected. Remarkably, probe SNAN-3 exhibits both a dual-emission and dual-response for the detection of sulfide in aqueous solution.