Iodine‐DMSO Catalyzed β‐carboline Derivative Chemoselective Fluorescent Molecule for Detection of Fluoride and Cyanide Anion

Abstract In this work, a simple and highly sensitive fluorescent receptor 1 ‐( p ‐tolyl)‐4,9‐dihydro‐3 H‐ pyrido[3,4‐ b ]indole ( receptor 1 ), has been synthesized for the detection of fluoride and cyanide ions. The receptor 1 was very selective towards fluoride and cyanide anions over other anions such as Cl − , Br − , I − , HSO 4 − , NO 3 − , HPO 4 2− , and OAc − . Synthesized receptor 1 shows low detection limits 3.29 × 10 −8 M for fluoride ion, which was determined by UV–vis absorption. While LOD for cyanide was observed to be 61.5 nM. Importantly, while, receptor 1 produced binding constant for fluoride and cyanide in DMSO‐H 2 O (1:9, v/v) was found to be 5 × 10 −4 M −1 and 3.28 × 10 −5 M −1 , respectively. The variation in the optical and fluorescence spectroscopy confirms the formation of N─H⋯F − and N─H⋯CN − hydrogen bond of the pyrrolic proton The sensing mechanism displayed by receptor 1 for fluoride and cyanide ions was confirmed by 1 H‐NMR and FT‐IR spectroscopic along with density functional theory (DFT) calculations. Solution with the fluoride and cyanide ions in DMSO‐H 2 O (1:9, v/v) shows a color change from light yellow to blue under UV light and yellow to colorless in visible light.