A novel chemosensor for Fe3+ based on open–closed-loop mechanism and imaging in living cells

In this paper, a novel chemosensor (named L1) for Fe3+ based on the rhodamine 6G and o-vanillin has been synthesized, which can selectively recognize Fe3+. The L1 solution showed a distinguishable colour change by naked eye, and the fluorescence turns on response after the addition of Fe3+. In addition, the experimental results showed that the spirocyclic of L1 was opened by cooperation between L1 and Fe3+, and then the fluorescence emission after excitation of the mixture solution was detected with the change in solution colour. The complexation coefficient of L1 towards Fe3+ was 1:1. Furthermore, L1 for Fe3+ sensing had a remarkable low detection limit of 427 nM (UV) and 130 nM (fluorescence), which is far below the drinking water standards (0.3 mg/L) of China. Meanwhile, the in vivo imaging and cell viability assay experiments demonstrated that L1 could be used for sensing Fe3+ in vivo.