A multifunctional bisphenol A-based dual-fluorophore fluorescent probe for the detection of Fe3+: practical applications in water, fingerprint, and cell imaging.

BONR, a newly developed fluorescent probe, was prepared through the fusion of bisphenol A, dicyanoisophorone, and Rhodamine ethylenediamine. This probe enables the specific detection of Fe3+ ions, resulting in a synergistic enhancement of both its spectral properties and practical application. In an EtOH/HEPES (1:1, v/v, pH =7.0) system, BONR exhibits high selectivity for Fe3+, producing an "off-on" fluorescence switching response. The probe undergoes a color transition from pale yellow to orange-red under natural light, with a significant increase in fluorescence intensity when exposed to 365 nm ultraviolet (UV) light. This behavior remains stable in the coexistence of over 20 interfering ions. The binding of probe to Fe3+ occurs in a 1:1 stoichiometry, characterized by a binding constant of 2.38 × 105 M-1. It achieves a minimum detection limit of 2.92 × 10-7 M, maintains outstanding stability over the pH range of 4 to 10, and demonstrates reversible response characteristics. BONR has been effectively employed for accurate determination of Fe3+ in real water samples, rapid on-site colorimetric analysis, plant and cell imaging, and visualization of fingerprint tertiary structures. This probe represents tool for efficient Fe3+ detection in diverse contexts, underscoring its promising utility across environmental monitoring and biomedical fields.