Ratiometric covalent organic framework florescence sensor for detecting hydrazine produced from isoniazid metabolism in cell

Designing luminescent COFs with high fluorescence quantum yield is always a huge challenge. In this work, we synthesized COF TzDha through Schiff base reaction between 4, 4′, 4′'-(1,3,5-triazine-2,4,6-triyl) trianiline (Tz) and 2,5-dihydroxyterephthalaldehyde (Dha), and post-modified COF TzDha-AC was grafted by refluxing in acetic anhydride. TzDha-AC shows higher relative fluorescence quantum yield (Φf) in various organic solvents and water, which is approximately 1.35 to 5.31 times to TzDha. What’s more surprising, TzDha-AC shows excellent ratiometric effect when it is used to detecte hydrazine (N2H4). Detection mechanism is attributed to that hydrazine prevents the intramolecular charge transfer (ICT) from benzene ring to triazine ring of TzDha-AC, thus the emission blue shifted from 601 nm to 526 nm. The detection limit (DL) of N2H4 is calculated to be 0.038 mM in the linear range of 0−10 mM. In addition, we also use TzDha-AC to detecte hydrazine produced from isoniazid metabolism in mouse liver cells and find that TzDha-AC could be a new material employed for simple isoniazid metabolism in cell.