Aromatic aldehyde based chemosensors for fluoride and cyanide detection in organic and aqueous medium: Ascertained by characterization, Spectroscopic and DFT Studies

Abstract In the present investigation, a series of new aromatic aldehyde based chemosensors (S1-S4) have been sensibly designed and synthesized by the simple condensation reaction and their anion sensing properties were investigated. The compounds were characterized by spectroscopic techniques such as FT-IR, UV-Visible, 1 H NMR, 13 C NMR and ESI-MS. The probes exhibited high sensitivity and selectivity towards fluoride and cyanide ions over the anions such as Br - , HSO - 4 , Cl - , OH - , I - , NO - 2 and NO - 3 in dry DMSO and DMSO-water mixture (DMSO: H 2 O 9:1 v/v). The binding mechanism of fluorometric chemosensors with N-H-F and N-H-CN ion was determined based on 1 H NMR titration and were also theoretically supported by DFT (Density functional theory) calculation. The stoichiometry and binding constant (Ka) of the host-guest complexes formed were determined by the Benesi–Hildebrand (B–H) plot and Job's method respectively. Finally, economically visible paper-based colorimetric “test stripes” of (S1-S4) were fabricated to the detection of F - and CN - ions in 100% aqueous solution.