An efficient protocol for the solid-phase synthesis of six members of a new class of extended macrocyclic
peptoids (based on ortho-, meta- and para-N-(methoxyethyl)aminomethyl phenylacetyl units) is
described. Theoretical (DFT) and experimental (NMR) studies on the free and Na+-complexed cyclic
trimers (3–5) and tetramers (6–8) demonstrate that annulation of the rigidified peptoids can generate
new hosts with the ability to sequestrate one or two sodium cations with the affinities and stoichiometries
defined by the macrocycle morphology. Ion transport studies have been also performed in order to better
appreciate the factors promoting transmembrane cation translocation.
