β-Diketone functionalized covalent organic framework for detection of europium(III) and successive detection of tetracycline antibiotics

Abstract

A new covalent organic framework (M-TT-COF) was designed and prepared by grafting Meldrum’s acid on the scaffold of TT-COF via esterification. M-TT-COF retained the crystal structure and high thermal stability of TT-COF. M-TT-COF as a “turn-on” fluorescence sensor can selectively identify and detect Eu3+ and tetracycline antibiotics in successive mode, the other metal ions, anions and antibiotics did not exert an obvious influence on the selective detection performance. The sensing performance has high sensitivity with low detection limits, 3.94 μM of M-TT-COF for Eu3+ and 0.56 μM of Eu@M-TT-COF for tetracycline antibiotics (oxytetracycline). In addition, both M-TT-COF and Eu@M-TT-COF have satisfactory recovery in the detection of Eu3+ and tetracycline antibiotics in the practical water samples, respectively. The mechanism of the fluorescence enhancement is attributed to the energy transfers from the β-diketone structure to Eu3+. This work successfully exploits a covalent organic framework as a “turn-on” fluorescence sensor in the identification and detection of rare earth metal ions and antibiotics.