Recognition of Al3+ through the off-on mechanism as a proficient driving force for the hydrolysis of BODIPY conjugated Schiff base and its application in bio-imaging

Two new BODIPY azine bearing quinoline and pyrazine attached Schiff base chemosensors (R1 and R2) have been synthesized and applied for the detection of Al3+ in CH3CN/H2O medium. Intramolecular hydrogen bonding makes both the sensors rigid and helps to encapsulate Al3+ in the cavity. The pink colour of R1 and R2 has been changed to green fluorescent upon excess addition of Al3+ which is only because of the hydrolysis of imine bond to regenerate compound 8. Another nitrogen atom present in quinoline and in pyrazine moiety made R1 and R2 more efficient in sensing of Al3+ ion compare to R1D, R2B and R2D. Cell viability and fluorescence microscopic experiments showed that the chemosensors are cytocompatible and can be used as an effective fluorescent probe for detecting Al3+ ion in the living cell.