Water-bridged hydrogen-bonding interactions with liquid-liquid interfacial Nanoarchitectonics: A molecular recognition strategy for preferential separation of Rh(III)

Liquid-liquid interfacial molecular recognition. • Water-bridged hydrogen-bonding networks as molecular sieving mechanism. • Viscoelasticity-guided molecular self-assembly for selective separation. • A novel strategy coupling interfacial states with separation performance. Controlling molecular recognition at liquid-liquid interfaces remains a formidable challenge due to the dynamic and complex nature of interfacial environments. In this study, using Dicyclohexano-18-crown-6 (DC18C6) as the molecular recognizer and sorbitan monooleate (Span80) as the viscoelastic regulator to enhance liquid film stability, a novel strategy based on viscoelastic molecular recognition is proposed, achieving controllable separation of PtCl 6 2- , PdCl 4 2- , and RhCl 6 3- . Under flow shear conditions, an ordered and dense hydrogen-bonded entangled network structure was formed at the oil-water interface by the surfactant Span80 and the macrocyclic molecule DC18C6. Spatial coordination with RhCl 6 3- anions was achieved via hydrogen-bonded water bridges interaction, through the synergistic cooperation of Span80 molecules with DC18C6 in either adjacent or opposing configurations, thereby enhancing the stability of the thin oil film. Compared to PdCl 4 2- and PtCl 6 2- , RhCl 6 3- anions exhibit a stronger hydration capacity, leading to the formation of a denser interfacial hydrogen-bonded self-assembled structure with DC18C6 and Span80 molecules. This structure can be further reinforced by adjusting the aqueous phase flow rate and the oil film thickness, thus enabling selective regulation of the differences in interfacial hydrogen‑bonding interactions. Download: Download high-res image (281KB) Download: Download full-size image