A simple colorimetric and ratiometric fluoride ion probe with large color change

Two colorimetric and ratiometric fluoride ion probes SHJ-1 and SHJ-2 based on the acylhydrazone skeleton have been developed. Among the eight anions (F-, Cl-, Br-, I-, ClO4-, H2PO4-, HSO4-, CH3COO-), the present probes showed high selectivity and sensitivity toward fluoride ion detection with obvious color change. Notably, the probe SHJ-1 exhibited a red shift of 145 nm upon fluoride sensing, which is the largest value among fluoride ion probes based on acylhydrazone derivates to date. (HNMR)-H-1 titration study and theoretical calculations suggested that the strong binding of the probe SHJ-1 to fluoride as well as the further deprotonation may facilitate the intramolecular charge transfer transition. These two probes are 1 : 1 complexed with fluoride ions, and the detection limits were calculated to be 1.24 mu M for SHJ-1 and 15.73 mu M for SHJ-2.

Automated summary

Two new colorimetric and ratiometric fluoride ion probes, SHJ-1 and SHJ-2, based on the acylhydrazone skeleton have been developed, showing high selectivity and sensitivity towards fluoride ion detection with significant color changes. SHJ-1 exhibited the largest red shift of 145 nm among fluoride ion probes based on acylhydrazone derivatives, indicating strong binding and potential charge transfer transitions.