QZ1 and QZ2: Rapid, reversible quinoline-derivatized fluoresceins for sensing biological Zn(II)

The preparation of QZ1, 2-[2-chloro-6-hydroxy-3-oxo-5-(quinolin-8-ylaminomethyl)-3H-xanthen-9-yl]benzoic acid, and QZ2, 2-[6-hydroxy-3-oxo-4,5-bis-(quinolin-8-ylaminomethyl)-3H-xanthen-9-yl]benzoic acid, two fluorescein-based dyes derivatized with 8-aminoquinoline are prepared and their photophysical, thermodynamic, and zinc-building kinetic properties are presented. Due to their low background fluorescence and highly emissive Zn(II) complexes, QZ1 and QZ2 have a large dynamic range fold fluorescence enhancements upon Zn(II) coordination.