Abstract

Electron-withdrawing natured di-nitro substituted, π···hole recognition element incorporated electron-deficient chemosensors L1, L1”, L2 and L2” have been designed and synthesised. UV-Vis and naked-eye colourimetric studies show that the nitro functionalization and numbers of nitro functionalization decide the selectivity of receptors towards cyanide anion sensing. When an electron-withdrawing natured, di-nitro substituted electron-deficient π···hole aryl moiety is present in a chemosensor, the aromatic – C-H group turns to be an additional hydrogen bonding donor, establishing selective colourimetric sensor for anion of our interest, cyanide. In addition, electron-deficient perfluoro phenyl moiety is also contributing in strengthening the sensors. The selectivity of these two chemosensors L1 and L2 towards cyanide anion is due to the overall cooperative effects of Ar-C-H···anion, traditional urea – N-H···cyanide, cyanide···π interactions present in the respective sensor molecules. To the best of our knowledge, this is the first report of colourimetric sensing of cyanide inclined by Ar-CH group.