Methionine-derived Schiff base as selective fluorescent “turn-on” chemosensor for Zn2+ in aqueous medium and its application in living cells imaging.

We describe the quantitative synthesis of a Schiff base derived from methionine and salicylaldehyde (SMSB) which displayed turn-on selective fluorescent chemo-sensing properties for Zn 2+ in buffered CH 3 CN/H 2 O (1:1) solution. In physiological pH (7.2 buffered) SMSB exhibited high selectivity and sensitivity toward Zn 2+ over the other selected metal ions. Upon the addition of Zn 2+ 33 folds of emission enhancement was observed in SMSB and limit of detection ( C L ) for Zn 2+ was found to be 5.0 × 10 −7 M. This binding phenomenon was studied by 1 H NMR and HR-MS analysis. Mass spectrometry analysis revealed that SMSB interacts with Zn 2+ and form a 1:1 complex, also confirmed by Job's plot. This probe was completely retrieved by adding EDTANa 2 solution, exhibited a fluorescent quenching effect by removing Zn 2+ from the sensor. SMSB was observed to have a good tolerance for fluorescence detection of Zn 2+ in pH range 6–10. Furthermore it is successfully investigated for living cells imaging using MCF-7 cells. Combine experimental results indicated SMSB to be a useful and powerful chemosensing probe for Zn 2+ in water as well as in living cells. [ABSTRACT FROM AUTHOR]