Simple Schiff-Base Covalent Organic Framework Nanoprobe for Resonance Rayleigh Scattering Detection of Trichlorophenol

Utilizing 1,3,5-triformylphloroglucinol (Tp) and tetramethylbenzidine (TMB) as functional monomers, nano Fe₃O₄ as the substrate, and 2,4,6-trichlorophenol (TCP) as the model molecule, a Schiff-base bond-based covalent organic framework nanoprobe (Fe₃O₄@COF) with specific recognition capability for TCP was synthesized through a microwave-assisted procedure. The nanoprobe was characterized through a comprehensive suite of techniques, including absorption spectroscopy, resonance Rayleigh scattering (RRS), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and zeta potential analysis. It exhibited a significant RRS peak at a wavelength of 510 nm. As the concentration of TCP increased, the resonance Rayleigh scattering energy transfer (RRS-ET) effect was intensified, leading to a decrease in the RRS signal intensity detected at 510 nm. The magnetic separation enrichment procedure demonstrates a linear response varying between 0.0025 and 0.05 μmol/L, with a detection limit (LOD) of 0.0016 μmol/L for TCP. Leveraging these characteristics, we developed an RRS-ET method that enables rapid, simple, selective, and sensitive detection of TCP.