A novel fluorescence sensor based on Zn porphyrin MOFs for the detection of bisphenol A with highly selectivity and sensitivity

In this study, we designed a zinc-based porphyrin metal-organic framework (Zn-TCPP-MOF) for ultra-sensitive and quantitative detecting BPA as a novel luminescent sensor. The fluorescence experiments revealed that the detectable limit of Zn-TCPP-MOF against BPA was far lower than many other reportorial methods. Moreover, an apparent quenching merely occurs when Zn-TCPP-MOF encountered BPA compared with the other phenolic compounds that usually coexist with BPA in food plastic packaging and it will not be interfered as well. During the adsorption experiments, the Zn-TCPP-MOF exhibited the most evident adsorption performance for BPA, the zeta potential tests showed the other phenolic compounds could not significantly change the surface potential of Zn-TCPP-MOF except BPA. The highly sensitive and selective fluorescence quenching mechanism as follow, the structural characteristics of BPA and Zn-TCPP-MOF make them conducive to electrostatic interaction that strengthens the adsorption of Zn-TCPP-MOF to BPA. Furthermore, based on cyclic voltammetry (CV) and Kubelka-Munk diagram to calculate molecular orbital energies, we found that the excited state of the ligand (TCPP) in MOFs is at a higher energy level than the LUMO of BPA which allows existing a driving force for the transfer of excited electrons from TCPP to BPA, thus promote the occurrence of luminescence quenching.