A coumarin based Schiff base probe for selective fluorescence detection of Al and its application in live cell imaging.

A new coumarin based Schiff base compound, CSB-1 has been synthesized to detect metal ion based on the chelation enhanced fluorescence (CHEF). The cation binding properties of CSB-1 was thoroughly examined in UV-vis and fluorescence spectroscopy. In fluorescence spectroscopy the compound showed high selectivity toward Al ion and the Al can be quantified in mixed aqueous buffer solution (MeOH: 0.01M HEPES Buffer; 9:1; v/v) at pH7.4 as well as in BSA media. The fluorescence intensity of CSB-1 was enhanced by ~24 fold after addition of only five equivalents of Al. The fluorescence titration of CSB-1 with Al in mixed aqueous buffer afforded a binding constant, K=(1.06±0.2)×10M. The colour change from light yellow to colourless and the appearance of blue fluorescence, which can be observed by the naked eye, provides a real-time method for Al sensing. Further the live cell imaging study indicated that the detection of intracellular Al ions are also readily possible in living cell.