Supramolecular assembly strategy of multinuclear platinum(ii) complexes for proof-of-concept detection and extraction of perfluorohexanoic acid.

Wide applications of per-/poly-fluoroalkyl substances (PFASs) in manufacturing fluorinated-polymer coatings and products pose serious health and environmental threats due to their highly chemical robustness. The development of efficient sensors for detecting persistent organic pollutants is thus essential. In this study, we present the supramolecular assemblies of multinuclear platinum(ii) complexes, which demonstrate the capability to detect and extract perfluorohexanoic acid (PFHxA) in deionized water. These platinum(ii) complexes have exhibited remarkable photophysical properties and supramolecular self-assembly in mixed organic solvents, driven by Pt(ii)⋯Pt(ii) and π-π stacking interactions, to form two-dimensional supramolecular polymers with hexagonal and rectangular packing, manifested as sheet-like nanostructures. Specifically, the dynamic association of PFASs with the resulting nanosheets formed by platinum(ii) complexes induces significant changes in the UV-vis absorption and emission spectra. Mechanistic studies, supported by molecular dynamics simulations, suggest that these pronounced spectroscopic changes are induced by the strong interactions of PFASs with platinum(ii) complexes and the surrounding solvent molecules. By means of liquid-phase extraction, we have demonstrated the innovative use of platinum(ii) supramolecular polymer networks for proof-of-concept detection and extraction of PFHxA in deionized water. This work provides important insights into the fundamental molecular design principles that are crucial for the future development of novel supramolecular functional materials.