Argentivorous Molecules Bearing Two Aromatic Side-Arms: Ag+–π and CH−π Interactions in the Solid State and in Solution

Abstract

Seven double-armed cyclens bearing two aromatic side-arms, at the 1- and 7-positions of the cyclens, were prepared via three steps from dimethyl 2,2'-iminodiacetate. The X-ray structures of the Ag(+) complexes and Ag(+)-ion-induced (1)H NMR spectral changes suggest that the two aromatic side-arms cover the Ag(+) ions incorporated in the ligand cavities, as if the aromatic ring "petals" catch the Ag(+) ions in the way a real insectivorous plant (Venus flytrap) catches insects, using two leaves. It is also reported that the CH-π interactions between the aromatic side-arms, as well as the Ag(+)-π interactions, are crucial for double- and tetra-armed cyclens to work as argentivorous molecules.