A coumarin based Schiff base probe for selective fluorescence detection of Al3+ 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 Al3+ ion and the Al3+ can be quantified in mixed aqueous buffer solution (MeOH: 0.01 M HEPES Buffer; 9:1; v/v) at pH 7.4 as well as in BSA media. The fluorescence intensity of CSB-1 was enhanced by similar to 24 fold after addition of only five equivalents of Al3+. The fluorescence titration of CSB-1 with Al3+ in mixed aqueous buffer afforded a binding constant, K-a = (1.06 +/- 0.2) x 10(4) M-1. 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 Al3+ sensing. Further the live cell imaging study indicated that the detection of intracellular Al3+ ions are also readily possible in living cell. (C) 2016 Elsevier B.V. All rights reserved.