A novel turn-on Schiff-base fluorescent sensor for aluminum(iii) ions in living cells

Abstract

(E)-4-Methoxy-N-((8-methylquionline-2yl)methylene)aniline (L) was successfully synthesized and characterized. The complexation behavior of L with different metal ions was studied using UV-Vis absorption spectroscopy and fluorescence spectroscopy. Results showed that the sensor (L) exhibited a 38-fold enhancement in fluorescence at 517 nm after adding 10 equiv. of Al³⁺ ions. Such fluorescent responses could be detected by the naked eye under a UV-lamp at 365 nm. The complex solution (L–Al³⁺) showed reversibility with EDTA and the complex was a 1 : 1 ratio according to Job’s plot and electrospray ionization mass spectroscopy (ESI-MS). A photoinduced electron transfer (PET) mechanism was considered to be operational for fluorescence enhancement. The detection limit of Al³⁺ was calculated to be 1.2 × 10⁻⁷ M, a satisfying level to detect Al³⁺ in the micromolar scale. Importantly, the chemosensor L could be used to detect and quantify Al³⁺ in living cells. Therefore, this sensor has the ability to be a practical system for monitoring Al³⁺ concentrations in biological systems.