Design and characterization of high performance fluorescent probe for neutral red based on fluorescein monoaldol-3-acetyl coumarin

•Fluorescent organic small molecule probes for the detection of neutral red substances were developed for the first time.•The probe is bound to the neutral red by ionic bonding while FRET occurs, resulting in quenching of the fluorescence.•It has good water solubility and has been successfully applied to the detection of neutral red content in real water samples. Based on the fluorescence resonance energy transfer (FRET) principle, a yellow-green light fluorescent probe was designed and synthesized for the detection of neutral red using fluorescein monoaldehyde-3-acetylcoumarin as the fluorophore. The fluorescein moiety in the probe structure is readily interchangeable and heterogeneous in the form of an anion, and the neutral red is a quaternary ammonium salt structure with N. Therefore, the two are bound together in the form of ionic bonds through the mutual attraction of anions and cations. At the same time, FRET occurs, resulting in the absorption of the fluorescence emitted by the probe by the neutral red molecule, leading to a significant quenching of its fluorescence. The probe has a high selectivity for neutral red with a linear range of 0–30 μM and a detection limit of 8. 68 μM. Furthermore, the fluorescent probe has been successfully applied to the detection of neutral red content in real water samples with a recovery of 101 %-115 %. The probe has promising potential in the quantitative detection of neutral red.