A Turn-On Fluorescence Probe for Selective Detection of Al3+ in Aqueous Environment: Crystal Structure, Theoretical and Cell Imaging Studies

A furan-based water soluble fluorescent probe (E)-N '-(2,4-dihydroxybenzylidene)furan-2-carbohydrazide (DBF) has been synthesized and characterized by H-1 NMR, C-13 NMR, ESI-mass spectroscopy and single crystal X-ray diffraction techniques. The synthesized probe exhibits a turn-on fluorescence response towards Al3+ in Tris-HCl buffer (10 mM) with no significant interference from other metal ions. The strong fluorescence in the presence of Al3+ is attributed to the CHEF (chelation enhanced fluorescence), inhibition of PET (photo-induced electron transfer) and C=N isomerization. 1 : 1 stoichiometric ratio between DBF and Al3+ was rationalized by Job's plot. Binding constant and LOD were calculated to be 1.031x10(5) M-1 and 6.34x10(-8) M, respectively. MTT assay on live A549 cells indicated no serious cytotoxicity in the cells even at higher concentration. Further, DBF was successfully used for the detection of accumulated Al3+ in the cytoplasm of cells.