Synthesis and characterization of a europium coordination polymer as a fluorescent sensor for the selective detection of PO43-, DTZ, and NFT

A new europium coordination polymer [Eu(2,3 '-oba)(2,3 '-Hoba)(IP)]n (Eu-CP) has been synthesized by hydro-thermal reaction using 2,3 '-oxbis (benzoic acid) (2,3 '-H2oba) and 1H-imidazole [4,5-f] [1,10]-phenanthroline (IP). The semi-rigid ligand 2,3 '-H2oba and large rigid ligand IP form a 1D chain structure of the Eu-CP, which is further stacked into a 3D supramolecular architecture through C-H center dot center dot center dot O and O-H center dot center dot center dot N hydrogen bonding. Below 400 degrees C, the Eu-CP does not decompose. It shows good chemical stability in common solvents and aqueous solutions with pH in the range of 3-12. The Eu-CP emits strong red luminescence, attributed to the 5D0 -> 7FJ (J = 0-4) transitions of the Eu3+ ion. The luminescence quantum yield and lifetime are 61% and 0.94 ms, respectively. The Eu-CP has a broad absorption in the range of 200-400 nm, with a maximum excitation wavelength of 365 nm. Furthermore, Eu-CP is used as a sensor for the detection of PO43-, dimetridazole (DTZ), and nitro-furantoin (NFT) in aqueous systems, and NFT in biological samples (calf serum) based on the luminescence quenching effect. Notably, luminescent Eu-CP@film was prepared for sensing PO43-, NFT, and DTZ, which can be reused more than 20 times, facilitating a visually simple and rapid online detection platform. In addition, we also studied the luminescence quenching mechanism of Eu-CP by analytes.