Exploring fluorescent covalent organic frameworks for selective sensing of Fe3+

Covalent organic frameworks (COFs) have been widely applied in gas capture and separation, but the fluorescent property of COFs with large -conjugated system tends to be underexplored. Here we report the fluorescent properties of several COFs including TaTa, DhaTab, TRITER-1 and TzDa and the effect of metal ions of Na+, Mg2+, K+, Ca2+, Cu2+, Zn2+, Pb2+, Ag+, Cd2+ and Fe3+ on the fluorescence of these COFs. The results show that only Fe3+ significantly quenched the fluorescence of the studied COFs. The possibility of the four COFs for selective sensing of Fe3+ was demonstrated. The possible mechanism of the effect of Fe3+ on the fluorescence of the COFs was based on the absorption competition quenching.