Polymerization Time-Optimized Covalent Organic Framework for Ultrasensitive Ethylene Glycol Sensing.

Ethylene glycol (C2H6O2) is a widely used yet toxic compound, requiring energy-efficient detection methods beyond prevalent high-temperature sensors. Here, an imine covalent organic framework (COF-TPC) was synthesized at room temperature (RT) using 2,4,6-trihydroxy-benzene-1,3,5-tricarbaldehyde (Tp) and 2,5-dichlorobenzene-1,4-diamine (Pa-Cl) as ligands, with acetic acid as a catalyst. The structure-property relationship was investigated by controlling Schiff base reaction time (1-70 h), yielding four sensors (COF-T-30, COF-T-40, COF-T-50, and COF-T-60) for testing. Gas sensing data revealed that the COF-T-50 sensor exhibited a response of 6107% to 500 ppm C2H6O2, significantly outperforming the other sensors. It also exhibited outstanding selectivity toward C2H6O2 among 13 gases, along with excellent repeatability and moisture resistance. DFT calculations elucidated the adsorption mechanism and the origin of its exceptional selectivity. This work provides a new approach for rapid, stable C2H6O2 detection using COFs, expanding their application scope.