A Small-Molecule Fluorescent Probe Featuring an Iminophosphorane Linker for Sequential Detection of Sn2⁺ Ions and Water with Bioimaging Applications

Abstract

A novel small-molecule fluorescent probe, NAP-TPP, derived from 1,4-naphthalic anhydride and incorporating an iminophosphorane functionality, has been developed for the sequential detection of Sn²⁺ ions and moisture. This work represents the first investigation into the metal ion complexation capabilities of fluorescent iminophosphorane derivatives for sensing applications. Upon coordination with Sn²⁺, the probe undergoes a distinct fluorescence change accompanied by a visible colorimetric shift, indicative of complex formation. The probe exhibits excellent aqueous stability and further demonstrates the ability to visualize Cu²⁺ ions in various cultured cell lines. Notably, the Sn²⁺ complex formed under anhydrous conditions functions as a highly sensitive ratiometric fluorescent sensor for trace levels of moisture. Collectively, these findings establish NAP-TPP as an effective dual-purpose sensing platform for detecting Sn²⁺ ions and monitoring moisture.

Keywords: 1,4‐Napthalic anhydride; Cell imaging; Density function theory; Fluorescent probe; Iminophosphorane.