Switching Ion Binding Selectivity of Thiacalix[4]arene Monocrowns at Liquid–Liquid and 2D-Confined Interfaces

Understanding the interaction of ions with organic receptors in confined space is fundamental importance and could advance nanoelectronics sensor design. In this work, metal ion complexation conformationally varied thiacalix[4]monocrowns bearing lower-rim hydroxy (type I), dodecyloxy II), or methoxy III) fragments was evaluated. At liquid–liquid interface, alkylated thiacalixcrowns-5(6) selectively extract alkali according to induced-fit concept, whereas crown-4 were ineffective due distortion crown-ether cavity, as predicted by quantum-chemical calculations. type-I ligands, alkali-metal extraction solvent-accessible cavity prevented, which resulted competitive Ag+ sulfide bridges. Surprisingly, amphiphilic type-I/II conjugates moderately extracted other ions, attributed calixarene aggregation salt aqueous phase supported dynamic light scattering measurements. Cation–monolayer interactions at air–water interface monitored surface pressure/potential measurements UV/visible reflection–absorption spectroscopy. Topology-varied selectivity evidenced, towards Sr2+ (crown-4), K+ (crown-5), (crown-6) Na+ Ca2+ Cs+ type-II receptors. Nuclear magnetic resonance electronic absorption spectroscopy revealed exocyclic coordination ligands cation–π ligands.