Synthesis, characterization, and hydrazine sensing property of two covalent organic frameworks

Abstract Sensitive and efficient detection of hydrazine is of great significance because hydrazine is a highly toxic organic molecule, which can pose great threats to human health. Herein, two covalent organic frameworks (COFs) modified with ester groups in the pores, TAPB‐DHE and TAPT‐DHE, have been successfully synthesized via esterification reaction. Both of the two COFs have good crystallinity, thermal stability, and fluorescence properties. TAPB‐DHE can be used as a turn‐on fluorescence sensor for the sensitive detection of trace hydrazine in aqueous solution with a detection limit of 0.40 μM and a wide linear range of 0–100 μM due to the fluorescence enhancement of TAPB‐DHE caused by the chemical reaction between hydrazine and TAPB‐DHE, in which the ester group of the COF is converted into hydroxyl group, leading to the restriction of the intramolecular charge transfer (ICT) effect. This work provides a reference for the design of COFs with hydrazine recognition function and a helpful expansion for the practical application of COFs.