Construction of a Fluorescence‐Based Logic Gate Seeing the Effect of Perchlorate Ions on Hemicyanine Dye–β‐Cyclodextrin Complexes to Certify Safe Drinking Water

Perchlorate ions (ClO 4 − ) are prevalent contaminants in the surface, and drinking water that disrupt thyroid function by competitively inhibiting the sodium‐iodide symporter (NIS), posing significant health risks. Here, fluorescence‐based logic gates have been constructed by leveraging the binding interactions between a hemicyanine dye, 4‐[4‐(dimethylamino)‐styryl]‐1‐docosylpyridinium bromide (DASPC22) and β ‐cyclodextrin ( β ‐CD) that could be useful to know whether ClO 4 − ions in water are within the toxicity range or not. In aqueous media, DASPC22 forms nonfluorescent H‐aggregates, but fluorescence is enhanced upon forming host‐guest inclusion complexes with β ‐CD. At low ClO 4 − ions concentrations, fluorescence intensity further increases due to enhanced complex stability through hydrogen bonding. ONIOM‐based quantum chemical calculations have supported this phenomenon. The enhancement of fluorescence intensity of DASPC22 in the presence of β ‐CD and a low concentration of ClO 4 − ions leads to the construction of a YES logic gate that would enable one to quantify ClO 4 − ions’ toxicity range in water. Dual‐input‐single‐output AND and INHIBIT logic gates with low and high concentrations of ClO 4 − ions, respectively, have also been constructed. The present system could be useful in addressing safety concerns related to perchlorate contamination of water.