Covalent Organic Frameworks with Electron-Rich and Electron-Deficient Structures as Water Sensing Scaffolds.

Covalent organic frameworks (COFs) have potential applications in gas storage, catalysis, proton conduction, sensing, and chemical removal etc., due to their highly crystalline structure, good stability, porosity, as well as structural and functional controllability. Herein, by using electron-rich group, 2,5-bis(methylthio)terephthalaldehyde (BMTA), and electron-deficient group, 1,3,5-tris-(4-aminophenyl)triazine (TAPT) as building blocks, TAPT-BMTA-COF is constructed through Schiff-base reaction. TAPT-BMTA-COF has high crystallinity, porosity, big Brunauer-Emmett-Teller surface area (BET), good chemical and thermal stability, and commendable solvatochromic properties. It can be used as the water sensing scaffold to detect the trace water in organic solvents due to the fluorescence quenching of the COF caused by the interaction between water and TAPT-BMTA-COF.