A novel fluorescence enhancement Al(III) sensor based on C1 symmetric Binol imine derivative: Recognition, binding mechanism and Bio-imaging application

A novel C1 symmetric Binol imine Schiff base fluorescence sensor (Sa,R)-6 was designed and synthesized by using (S)-Binol-3-aldehyde as initial material. The probe showed great fluorescence enhancement at λ = 552 nm and visual light yellow fluorescence under 365 nm UV lamp irradiation with presence of Al3+. Quantitative test was feasible from 10 μM to the detection limit which reaches nanomole level. Job's plot, HRMS spectroscopic and NMR titration indicated the formation of Al[(Sa,R)-6]2+. DFT calculations suggested the coordination reaction lead to a CHEF effect and the "turn-on" fluorescence response. Moreover, (Sa,R)-6 was well tolerable to human normal astrocyte cell line HA-1800 in cell viability test so that it could be utilized for detecting trace Al3+ in vitro in a concentration-dependent manner via confocal imaging which proved its potential of diagnosis and treatment of Aluminum related diseases.