Selective recognition of cyanide ion by colorimetric hydrazide based Cr(III) chemosensor

A novel chemosensor based on Nifuroxazide Cr(III) complex was developed for recognizing CN^– over other tested anions e.g., F^–, Cl^–, Br^–, I^–, CH₃COO^–, NO₂^–, PO₄^3–, and SCN^– in DMSO–H₂O (9:1, v/v) and THF. Without any interference from the tested anions, UV–vis spectroscopy was used to investigate the recognition of CN^–. The deprotonated species that resulted from the ionization of the phenolic group may be the cause of the color shift that occurred after adding CN^– to the solution of the Cr(III) complex. The charge transfer interaction between the electron-donor unit and the electron-deficient nitro-furan moiety was improved as a result of the ionization of the phenolic group. The fact that the developed color vanishes in protic polar solvents e.g., H₂O, CH₃OH, and C₂H₅OH may lend credence to this assumption. The Lambert–Beer's law was obeyed in the concentration ranges of 3.4 × 10⁻³–3.4 × 10⁻⁵ M and 1.0 × 10⁻⁴–5.0 × 10⁻⁶ M in DMSO–H₂O (9:1, v/v) and THF, respectively, reflecting the significant role of the solvent in controlling the sensitivity of the developed probe. The electronic transitions were investigated by executing time-dependent density functional theory calculations.