A fluorescent covalent triazine framework consisting of donor–acceptor structure for selective and sensitive sensing of Fe3+

Abstract

A covalent triazine framework (FL-CTF) consisting of electron-donating thiophene units and electron-accepting benzothiadiazole units was synthesized using Suzuki polycondensation. The successful polymerization and chemical structure of FL-CTF were revealed by a combination of FTIR, solid-state 13C NMR, and XPS. The as-prepared FL-CTF with donor–acceptor structure shows fluorescence property in DMF. A series of fluorescent measurements were performed to ascertain the sensing property of FL-CTF toward metal ions. The fluorescence quenching appears upon addition of Fe3+ and the fluorescence intensity recovers facilely after the addition of a chelating agent tetrabutylammonium fluoride. To understand the fluorescence quenching and recovery process, UV–Vis absorption spectra and XPS were further measured. The electron transfer from FL-CTF to electron-deficient Fe3+ and the interaction between Fe3+ and nitrogen sites in FL-CTF may lead to fluorescence quenching. The interference experiments indicated that FL-CTF can selectively detect Fe3+ in the presence of other metal ions or different counter anions. Moreover, FL-CTF can detect Fe3+ with high sensitivity with the detection limit of 0.78 μM. These results demonstrate that FL-CTF has high selectivity and sensitivity toward Fe3+ and thus is expected to be a fluorescent sensor in practical applications.