Selective and sensitive dual channel sensing of cyanide by bithiophene fluorophore-based D-π-A type chemodosimeters - Spectral and theoretical studies.

Two new chemodosimeters (SA2-Ind and SA2-Thio) were designed and synthesised by coupling Bisthiophene carboxaldehyde fluorophore with the two different electron-withdrawing salt cores. The developed probes exhibited instantaneous, remarkable colour and fluorescence changes selectively with CN- over other anions. The nucleophilic addition of CN- at the imine carbon atom was the sensing mechanism, as evinced by the NMR and HR-MS analyses. The computed low LoD for SA2-Ind (53 nM) and SA2-Thio (0.46 μM) were well below the safe limit established by the WHO, implying the suitability of the probes CN- detection in real samples. The DFT/TD-DFT analyses sturdily verified the experimental observations. The instant colour and fluorescent changes showed by the test-buds coated with the probes, upon contact with CN-, unveiled their on-site monitoring ability. The good recovery percentage (96.6-100%) observed in CN- estimation in three different natural water samples by the spiking method strongly authenticated its applicability in real complex matrices.