An imine COF as a dual-functional fluorescent sensing platform for vitamin K1 and water

Luminescent covalent organic frameworks (LCOFs) with large π-conjugated system were a family of crystalline porous materials with promising applications. However, the actual application and quenching mechanisms of the LCOFs with dual-functionality remain poor understood. Here, a micro-mesoporous luminescent covalent organic framework (LCOF-DT) with high crystallinity and good stability was prepared by the solvothermal method using 1, 3, 5-tri-(4-aminophenyl) benzene and 2, 5-dihydroxyterephthalaldehyde as monomers through Schiff base condensation reaction. The LCOF-DT exhibited not only a good sensitivity and colorimetric visualization for water in conventional organic solvents over a relatively broad linear range (0 %-50 %) but also showed exceptional fluorescent recognition capability for vitamin K1, even in the presence of 17 different competing substrates. Additionally, a sensitive, specific, rapid, and practical fluorescent method for vitamin K1 detection in the commercially vitamin K1 tablets was developed. Based on the aforementioned research, designing covalent organic frameworks with multifunctional fluorescent response would be a tendency in the further application of detection technology.