A simple coumarin-based colorimetric and ratiometric chemosensor for acetate and a selective fluorescence turn-on probe for iodide

A novel colorimetric and ratiometric anion chemosensor bearing phenylhydrazone- coumarin moieties as recognition sites was rationally designed and synthesized. Upon addition of a series of anions to receptor R1 in 1:1 CH₃CN/H₂O, only the appearance of the solution of receptor R1 with acetate showed a color change from pale yellow to purple (bathochromic shift from 411 to 573 nm) which can be detected by the naked eye at parts per million. The probe R1 developed herein represents the rational design of a fluorescence turn-on probe for iodide, which is a notorious fluorescence quencher due to the heavy atom effect. The probe developed herein represents the fluorescence amplified probe for iodide.