A Luminescent Ionic/Host-Guest Framework for Rapid and Selective Detection of 2,4,6-Trinitrophenol Derivatives

Flexible porous frameworks that are engineered with intermolecular interactions have emerged as a promising class of porous materials for various potential applications. In this work, an ionic-supramolecular framework is designed and synthesized via stepped host-guest inclusion of an ionic complex composed of a cationic pillar[5]arene and a polyanionic cluster with a tetraphenylethene unit grafting with pentyl cyanide groups by proceeding with a [4 + 2] stoichiometric assembly. Owing to high specific surface area, dynamically adaptive interlayer architecture, and the incorporated luminescent sites, the formed ionic-supramolecular framework exhibits exceptional performance as an effective probe for the detection of 2,4,6-trinitrophenol (TNP) with high sensitivity, selectivity, and high speed. The sensing delivers a linear fluorescent response to TNP over the concentration range of 0–9 μM within a time of 5 s, achieving a limit of detection of 46 ppb and a Stern–Volmer quenching constant of (9.31 ± 0.04) × 10 4 M –1 at the 95% confidence level. Mechanistic investigations support a dual quenching pathway involving both photoinduced electron transfer and Förster resonance energy transfer through the characterizations of ultraviolet photoelectron spectroscopy, density functional theory calculation, and spectral overlap analysis. Collectively, these findings reveal the broad applicability by the rational design and engineering of supramolecular frameworks as a chemical detection platform.