Chromogenic and fluorogenic off-on-off chemosensor for selective and sensitive detection of aluminum (Al3+) and bifluoride (HF2-) ions in solution and in living Hep G2 cells: synthesis, experimental and theoretical studies

A simple pyridine-dicarbohydrazide based colorimetric and fluorometric chemosensorLwas designed and synthesized for Al(3+)ion sensing in organo aqueous solution. In the presence of Al(3+)ions, probeLexhibited visible color changes and fluorescence enhancement (20-fold) due to Al(3+)induced chelation-enhanced fluorescence (CHEF) effects. ChemosensorLrevealed high selectivity toward Al(3+)ions by turn-on fluorescence among the other competitive metal ions examined with a detection limit of 0.8 mu M. ProbeLwas found to bind with Al(3+)ions in a 1 : 2 (probe : metal) stoichiometric fashion, with an association constant (K-a) of 4.26 x 10(4)M(-2). In addition, DFT and TDDFT calculations were carried out to recognize the binding nature and electronic properties of probeLand its Al-complex. Furthermore, thein situprepared [L-Al] complex was able to detect HF(2)(-)anionsviaa metal displacement strategy. The bioimaging application of Al(3+)and HF(2)(-)was implemented in living human liver cancer cells (Hep G2).