A simple Michael acceptor type quinoline derivative for highly selective sequential recognition of CN− and Cu2+ in aqueous solution

Abstract

A 2-(quinolin-2-ylmethylene) malononitrile (6) chemosensor has been designed and synthesized. The fluorogenic properties of 6 toward different anions and metal ions were investigated in DMSO/H₂O (1 : 9, v/v) solution. Probe 6 exhibits high selectivity and sensitivity (5.09 × 10⁻⁸ M) to CN⁻ as fluorescence “off–on” behavior through Michael addition. Moreover, the in situ formed 6-CN⁻ is further utilized to sense the Cu²⁺ through complexation reaction with high selectivity and fluorescence quenching performance in aqueous water. Probe 6 has selectively detected CN⁻ in real water sample, and on test strips. The FTIR, ¹HNMR and ESI-MS spectroscopy supported the proposed mechanism of interaction.