Terpyridine functionalized α-cyanostilbene derivative as excellent fluorescence and naked eyes Fe2+ probe in aqueous environment

A novel carbazole derivative (L) functionalized by terpyridine was designed and synthesized. Its structure was fully characterized by FT-IR, HR-MS, H-1 NMR spectra. L formed J-aggregates and possessed aggregation-induced emission enhancement property in aqueous environment. In addition, compound L showed specific response to Fe2+ in UV-vis spectra at 557 nm in EtOH-H2O mixed solvent, owing to metal-to-ligand-charge-transfer (MLCT). The emission quenched much more sharply than other metal ions when adding Fe2+. The interaction between compound L and Fe2+ was analyzed by UV-vis and fluorescence spectrum titration. The limit of detection was calculated to be 1.63 mu M. The stoichiometric of L and Fe2+ was 2:1 confirmed by Job's plots. Competition experiment indicated that other metal ions caused little interference. In this way, L could be a fluorescent and "naked eyes" probe for Fe2+ detection. This dual mode Fe2+ sensor can be considered to have potential value in practical applications.