Specific detection of nonylphenol in ambient waters based on dinaphthyl fluorescent ionic liquids

Nonylphenol (NP) is a common pollutant with high biotoxicity in industrial waste waters, such as printing and dyeing, cleaning, preparation of surfactant and detergents, etc., and can disrupt the endocrine and reproductive system. Therefore, its emission is imperative to be monitored. To achieve the specific detection of NP, we herein synthesized a novel fluorescent ionic liquid (NAIm) bearing a double naphthalene ring. The fluorescent intensity of NAIm was significantly quenched upon the addition of NP, and the underlying quenching mechanism belonged to a static quenching mode. DFT theoretical calculations suggested that the band gap increased by 0.11 eV, where the ground state electrons were transferred from the HOMO orbitals of NP to the LUMO ones of NAIm. The specific detection of NP by NAIm was demonstrated to be feasible. NAIm was also able to identify and quantify NP in ambient samples, and the fortified recoveries for NP was in the range 89–110 %. The newly developed fluorescent ionic liquid holds great promise in specific detection of NP in environmental waters.