A porous and chemical stable Co(II)-based metal-organic framework for the selective fluorescence sensing of Fe3+ and tetracycline

As a novel class of sensing materials, metal-organic frameworks (MOFs) have been developed as promising candidates for application of efficient sensing. Herein, a stable Co(II)-based MOF (noted as Co-MOF) was selected as the fluorescent sensor for the exploration of its sensing ability towards metal ions and antibiotic molecules. The fluorescence sensing experiments suggested that Co-MOF exhibited selective and sensitive sensing of Fe3+ and tetracycline among other ions and antibiotic molecules. The Stern-Volmer quenching constant (Ksv) of Fe3+ and tetracycline (TC) were determined to be 1.38 × 104 M−1 and 1.77 × 104 M−1, respectively, while the limit of detection values were calculated as 6.04 μM for Fe3+ and 4.71 μM for tetracycline. Additionally, the sensing mechanism of Co-MOF was further explored by UV–vis absorption spectroscopy and density functional theory (DFT) calculation, indicating that the fluorescence quenching is attributed to synergistic effect of photoinduced electron transfer (PET) and energy competition.