A covalent organic framework rich in lanthanide Eu3+ binding sites for sensitive and selective determination of tetracycline

Herein, a valid fluorescence sensor using covalent organic framework (COF) coupled with Eu3+ is built for the detection of TC. Based on the Schiff base reaction, a new covalent organic framework (Bpydah-Tt-COF) rich in N atoms is synthesized by using [2,2′-bipyridine]-5,5′-dicarbaldehyde (Bpydah) and 1,3,5-triazine-2,4,6-triamine (Tt). Since the abundance of N atoms (up to 33.46%) on the skeleton of Bpydah-Tt-COF, more Eu3+ can facilely anchor on Bpydah-Tt-COF by means of post-modification. Therefore, a Eu3+-functioned covalent organic framework (Bpydah-Tt-COF@Eu) is synthesized and used for sensitive detection of TC via "antenna effect". And the detection sensitivity (3.1 nM) and detection range (from 0.08 to 35 μM) for TC by Bpydah-Tt-COF@Eu fluorescence sensor will be significantly improved due to more target analytes can be identified by Eu3+ on the Bpydah-Tt-COF@Eu. Besides, the Bpydah-Tt-COF@Eu fluorescence sensor has been successfully utilized for TC monitoring in actual samples with good precision (RSD<1.98%) and recoveries (99.89–105.1%).