An amphiphilic calix[6]arene, alone or complexed with an axle to form a pseudo-rotaxane, has been embedded into liposomes prepared from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and the permeability of the membrane-doped liposomes towards Cl- ions has been evaluated by using lucigenin as the fluorescent probe. The pseudo-rotaxane promotes transmembrane transport of Cl- ions more than calix[6]arene does. Surprisingly, the quenching of lucigenin was very fast for liposomes doped with the positively charged axle alone. Molecular dynamics (MD) simulations and quantum-chemical calculations were also carried out for providing a semi-quantitative support to the experimental results.
Keywords: Anion-π interactions; Calixarenes; Ion channel; Liposomes; Pseudo-rotaxanes.
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