A novel colorimetric and ratiometric fluorescent CN− sensor based on rhodamine B hydrazone derivatives in aqueous media and its application in sprouting potatoes

Abstract

A novel highly selective chemosensor Z based on rhodamine B hydrazone derivatives was designed and synthesized, and it showed both colorimetric and “turn-on” fluorescence responses for CN⁻ in an aqueous solution. The results showed that after adding CN⁻ ions in aqueous solution, the chemosensor Z showed significant color change from colorless to pale-yellow, which was visible to the naked eye, and it rapidly produced strong green fluorescence. The probe could distinguish CN⁻ by deprotonation and intramolecular charge transfer (ICT) mechanisms, as evidenced by ¹H-NMR titration and DFT calculations. In addition, the detection limit of the fluorescence response of the sensor for CN⁻ was 5.81 × 10⁻⁸ M, which was measured by titration. The chemosensor Z has been successfully used to detect CN⁻ in sprouting potatoes. Z-containing test strips have also been prepared, and they can be used as a colorimetric tool for CN⁻ detection in potential applications.