Bisphenol-based cyanide sensing: Selectivity, reversibility, facile synthesis, bilateral "OFF-ON" fluorescence, C-2 nu structural and conformational analysis

Abstract

A structurally characterized novel dual-pocketed tetra-conjugated bisphenol-based chromophore (fluorescence = 652 nm) was synthesized in gram scale in similar to 90% yield from its tetraaldehyde. Highly selective, naked-eye detection of CN- (DMSO/H2O) was confirmed by interferent testing. A detection limit of 0.38 mu M, within the permissible limit of CN- concentration in drinking water was achieved as mandated by WHO. The "reversibility" study shows potential applicability and reusability of Sen. Moreover, costeffective and on-site interfaces, application tools such as fabricated cotton swabs, plastic Petri dishes, and filter papers further demonstrated the specific selectivity of Sen for the toxic CN-. In addition, an easily available and handy smartphone-assisted "Color Picker" app was utilized to help estimate the concentration of CN- ion present. A dual phenol deprotonation mechanism is active and supported by H-1 NMR spectroscopic data and DFT calculation results. (C) 2021 Elsevier B.V. All rights reserved.