Synthesis of 3,5-diaryl substituted indole derivatives and its selective iodide ion chemosensing

In this contribution, we have synthesized series of 1-ethyl-3,5-bis[2-(aryl)ethenyl]-1H-indole based derivatives with different functional groups using Wadsworth–Emmons coupling. The sensing ability of the receptors has been studied for halides like tetrabutylammonium fluoride, chloride, bromide, iodide and bisulphate by UV–vis spectroscopy methods. In THF solution, compound A–E exhibits excellent selectivity with iodide ions over the other ions like tetrabutylammonium bromide (TBABr), tetrabutylammonium chloride (TBACl), tetrabutylammonium fluoride (TBAF) and tetrabutylammonium bisulphate (TBAHSO4). The indole cores were observed effectively and selectively recognized biologically important iodide was reported. Significant absorption change was observed only for tetrabutylammonium iodide and no change with other anions. The absorption spectra indicated the formation of complex between host and guest is in 1:1 stoichiometric ratio. The association constants of A–E for iodide ions were found to be 3.2 × 104 M−1, 3.9 × 104 M−1, 4.2 × 103 M−1, 2.9 × 103 M−1 and 2.14 × 103 M−1, respectively.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Development of simple and efficient heterocyclic based chemosensors is an active area of current global interest. ► Manuscript explores novel synthesis of indole based chemosensors and photophysical properties. ► All the compounds well characterized by analytical techniques and properties also have been reported. ► 3,5-Diaryl indole derivative has been highlighted as potential sensors for iodide ions.