A colorimetric and absorption ratiometric anion sensor based on indole & hydrazide binding units.

Abstract A colorimetric and absorption ratiometric anion sensor ( L ) based on indole and hydrazide binding units was designed and synthesized, and its recognition & sensing properties towards different anions were studied by naked-eye observations, UV–vis and 1 H NMR titration spectra. Sensor L could selectively recognize biologically important F − , AcO − and H 2 PO 4 − in DMSO over other anions, along with a significant change in its color and absorption spectrum, resulting from the formation of corresponding 1:2 ( L /F − ) and 1:1 ( L /AcO − and L /H 2 PO 4 − ) complexes. The 1 H NMR titration experiments proved that sensor L experienced deprotonation of NH fragment and produced [HF 2 ] − species, whereas a stable H-bonding complex was formed in the presence of AcO − and H 2 PO 4 − .