Pyrophosphate-selective fluorescent chemosensor based on ratiometric tripodal-Zn(II) complex: Application in logic gates and living cells

A new C-3-symmetry tri-arm 8-hydroxyquinoline based fluorescent chemosensor, termed THL has been designed and synthesized, and found to be a ratiometric and selective fluorescent detector of Zn2+ over a wide range of tested metal ions. The addition of Zn2+ to the solution of THL in aqueous-organic solvent induced the formation of a 1:3 ligand metal complex, THL center dot 3Zn(2+), which exhibits a remarkable enhanced fluorescent emission centered at 491 nm, with the disappearance of the fluorescent emission of THL centered at 405 nm due to the mechanism of internal charge transfer. These newly formed Zn2+ complex was shown to exhibit strong green fluorescence. In addition, this THL center dot 3Zn(2+) complex was found to act as selective 'turn-on' fluorescent sensor for pyrophosphate (PPi). Such fluorescence modulation behavior of THL and THL center dot 3Zn(2+) complex mimics the performance of a combinatorial logic circuit with INHIBIT and AND logic gates. Finally, THL was also successfully used to image intracellular Zn2+ ions in cultured RAW cells. (C) 2014 Elsevier B.V. All rights reserved.