Cubane Arrives on the Cucurbituril Scene

Cubane, an intriguing
chemical curiosity first studied in the early
1960s, has become a valuable structural motif and has recently been
involved in the structures of a great number of prospective compounds.
The first dicationic supramolecular guest 5 is prepared
and derived from a 1,4-disubstituted cubane moiety, and its binding
behavior toward cucurbit­[n]­urils (CBn) and cyclodextrins (CD) is studied. The bisimidazolium salt 5 forms 1:1 inclusion complexes with CB7, CB8, and β-CD
with the respective association constants (6.7 ± 0.5) ×
1011 M–1, (1.5 ± 0.2) × 109 M–1, and <102 M–1 in water. The solid-state structures of the 5@CB7 and 5@CB8 complexes are also reported.