An ionic-liquid-based low-dimensional fluorosensor for ultrasensitive detection of perchlorate ions in aqueous media

Abstract

An anthracene-coupled phenanthroimidazolate-based ionic liquid (APIL) is synthesized and processed via reprecipitation to yield its microstructured form (mAPIL). Structural and morphological characterization studies were performed using spectroscopic and microscopic techniques. Neat APIL displays bluish green photoluminescence upon excitation with 365 nm UV light; however, its emission is perceived as bright green-yellow by the naked eye, and it can be used as a fluorescent security ink under solvent-free conditions. In an aqueous suspension, mAPIL displays weak fluorescence, which is significantly enhanced upon exposure to ClO₄⁻ ions, driven by ion-induced molecular clustering, enabling sensitive detection with a limit of detection (LOD) of 12.7 nM, substantially below the regulatory limit established by the EPA for drinking water. A portable detection kit was fabricated for real-world applications, and performance validation using spiked environmental samples confirmed the system's practical utility. The present work demonstrates a promising strategy for the design of ionic-liquid-derived nanofluorosensors for ecological monitoring of hazardous ions, such as perchlorate.