Dual-emissive ratiometric probe integrating TP-BDB-COF and N-CDs@ZIF-8 for ultrasensitive hypochlorite detection in aqueous environments

A ratiometric fluorescence probe was developed by integrating a covalent organic framework (TP-BDB-COF) with N-doped quantum dots (N-CDs) encapsulated in zeolitic imidazolate framework-8 (N-CDs@ZIF-8), enabling highly sensitive and selective detection of hypochlorite (ClO⁻) in aqueous environments. The yellow-orange-emissive TP-BDB-COF, synthesized by the condensation of 2,4,6-triformylphloroglucinol (TP) and 3,3’-dimethyl-[1,1’-biphenyl]-4,4’-diamine (BDB), exhibited specific fluorescence quenching at 570 nm upon interaction with ClO⁻. The blue-emissive N-CDs@ZIF-8 served as a stable reference signal at 430 nm, enabling self-calibration via the ratiometric signal (F 430 /F 570 ). This dual-signal strategy significantly improved detection accuracy and reliability. This sensor exhibited a broad linear fluorometric response range of 0.05 to 200 µM for ClO⁻, with an exceptionally low detection limit of 22 nM. Moreover, its practical applicability was validated through analysis of real water samples, yielding satisfactory spike recoveries between 98.53% and 101.30%. This approach not only offers a robust method for monitoring ClO⁻ in complex matrices but also provides a versatile framework for constructing high-performance ratiometric sensors. Graphical abstract