Pentacyclic Nano‐Trefoil

Tetra‐armed cyclen (1) bearing two 4‐(4′‐pyridyl)benzyl and two 3,5‐difluorobenzyl groups and its Ag+ complexes were prepared and structurally characterized. The complexes formed between 1 and Ag+ undergoes a reversible structural transformation between a 2:2 dimeric complex and a 3:5 pentacyclic trefoil complex with changes in the Ag+/1 molar ratio. It was also revealed that the 3:5 trefoil complex could encapsulate benzene and [D6]benzene selectively in solid‐state. The benzene‐included structures are stabilized by C−H⋅⋅⋅F−C interactions between the benzene molecule and the ligand molecule. The reversible structural transformation between 2:2 (1/Ag+) dimer and 3:5 (1/Ag+) pentacyclic trefoil complexes based on the tetra‐armed cyclen with two 4‐(4′‐pyridyl)benzyl and two 3,5‐difluorobenzyl groups is reported. Also, the selective separation of a benzene molecule in the cavity of the trefoil was confirmed in the solid‐state.