1,8-Naphthalimide: A Versatile Platform for the Design of Fluorescent Probes Targeting Hydrogen Sulfide in Biological...

Hydrogen sulfide (H₂S) has emerged as an important gaseous signaling molecule involved in numerous physiological and pathological processes, including redox regulation, inflammation, and cellular signaling. Accurate detection of H₂S in biological systems is therefore essential for understanding its roles in health and disease. Among various fluorescent platforms, the 1,8-naphthalimide scaffold has attracted considerable attention due to its unique photophysical properties, structural tunability, and high sensitivity to substituent modification. This review summarizes recent advances in the development of 1,8-naphthalimide-based fluorescent probes for H₂S detection. The fundamental photophysical mechanisms associated with the 1,8-naphthalimide fluorophore, including intramolecular charge transfer (ICT), photoinduced electron transfer (PET), and Förster resonance energy transfer (FRET), are discussed in relation to probe design. Emphasis is placed on reaction-based sensing strategies, highlighting organic reactions that enable selective recognition of H₂S, such as reduction, nucleophilic addition, nucleophilic substitution, and intramolecular cyclization. Representative probes are summarized and compared with respect to sensing mechanisms and photophysical behavior. In addition, the current challenges of 1,8-naphthalimide-based H₂S probes are discussed. We hope this review will provide useful perspectives for the development of efficient 1,8-naphthalimide-based fluorescent probes for H₂S detection.