Luminescent zinc porphyrinic MOF as a ratiometric fluorescence sensor for determination of tetracycline hydrochloride

Two-dimensional luminescent metal-organic frameworks (2D LMOFs), have garnered significant attention for their unique fluorescent properties and highly accessible active sites, yet designing these LMOFs with target-dependent fluorescence for sensing remains a challenging endeavor. Herein, a zinc tetra(4-carboxyphenyl) porphine (Zn-TCPP) LMOF was prepared and first applied to the fast and sensitive sensing of tetracycline hydrochloride (TCH). Upon TCH exposure, the signature red fluorescence of Zn-TCPP at 609 nm diminishes, accompanied by the emergence of a 520 nm peak, which were originated from photo-induced electron transfer (PET) of Zn-TCPP to TCH and inner filter effect (IFE) of TCH towards Zn-TCPP, and the triggers of Zn-TCPP on the instinct fluorescence of TCH, respectively. Notably, the I_{520 nm}/I_{609 nm} fluorescence intensity ratio showed good linearity over a wide range of TCH concentrations (0.1‒25 μmol/L), with a limit of detection (LOD) of 65.4 nmol/L. Additionally, the Zn-TCPP probe showed good TCH selectivity and anti-interference properties. The probe’s practicability was also validated by detecting TCH in spiked tap water, milk and chicken samples. Furthermore, test papers impregnated with the Zn-TCPP probe were prepared, allowing the visual detection of TCH with a smartphone. Results suggest the developed method is suitable for practical TCH detection.