A sensitive naked eye probe based on spiropyran for exactness sensing of F ⁻ ions in aqueous

Most areas have long been affected by endemic fluorosis, which can lead to fluorosis bone disease and cardiovascular damage. The detection and treatment of fluoridated water has been of great concern. In this work, the sensors SP-1 and SP-2 were synthesized from naphthylamine and pyreneamine with carboxy-modified spiropyran via amidation reaction. The photoisomerization of spiropyran molecules under alternating ultraviolet/visible light irradiation resulted in changes in the conjugation system, which amplifies the combination between F − and the amide bonds of SP-1 and SP-2 molecules, enabling rapid and naked-eye detection of F − . Simultaneously, the impact of two distinct conjugated rings, pyridineamine and naphthaleneamine, on spiropyran detection of F − was investigated. Based on results from the UV spectrum, 1 HNMR, and DFT theoretical calculation, it was determined that both sensor SP-1 and SP-2 can detect F − with a binding ratio of 1:1. The detection limits for sensor SP-1 are 0.978 µM for F − , and SP-2 are 0.173 µM for F − . The detection limit of SP-2, with a larger chromophore than SP-1, is lower and exhibits a more pronounced phenomenon. This study holds significant practical implications for rapid anion detection in aqueous environments, visual recognition without the need for specialized equipment, and energy conservation.