Colorimetric, fluorometric, and electrochemical sensing of cyanide ion in aqueous media using merocyanine-ferrocene conjugate

Rapid detection of hazardous ions has received a considerable deal of attention in recent decades due to its usefulness in preserving a greener environment for humans. The severe toxicity of cyanide (CN-) ions is a major environmental problem. Therefore, a substituted merocyanine salt having a ferrocene segment was designed and synthesized with the expectation to yield a probe with colorimetric, and electrochemical properties. The merocyanine derivative was characterized by NMR, IR, and high-resolution mass spectrometric analysis. The merocyanine salt was screened for the colorimetric detection of toxic ions in aqueous media. Utilizing UV-vis, fluorescence spectroscopy, cyclic voltammetry, and digital image analysis, an acceptable limit of detection value was witnessed. A hypochromic and hypsochromic shift in the absorption spectra was observed in the presence of cyanide ions. The 1H NMR spectroscopy shows the interaction of CN- with the probe at the spiro-carbon of the merocyanine salt and metal center of the ferrocene segment. The electrochemical input during cyclic voltammetric studies resulted in the formation of C-C bonds on complexation with cyanide ions due to an increase in electron density on the nitrogen atom of the indoline segment. The limit of detection calculated using UV-visible spectroscopy was 2.28 mu M, fluorescence spectroscopy provided 1.48 mu M , and 0.61 mu M was witnessed using cyclic voltammetry.

Automated summary

Rapid detection of hazardous ions has been a significant focus in recent decades for its utility in protecting the environment. This study designed and synthesized a substituted merocyanine salt with a ferrocene segment to create a probe with colorimetric and electrochemical properties. The probe was able to detect toxic ions in aqueous media through UV-vis, fluorescence spectroscopy, and cyclic voltammetry, with acceptable limit of detection values observed. The interaction of the probe with cyanide ions was characterized using NMR and resulted in the formation of C-C bonds. The calculated limit of detection values were 2.28 μM using UV-visible spectroscopy, 1.48 μM using fluorescence spectroscopy, and 0.61 μM using cyclic voltammetry.