Adamantylated trisimidazolium-based tritopic guests and their binding properties towards cucurbit[7]uril and β-cyclodextrin

Two new homotritopic guests based on tris(benz) imidazolium salts with adamantane binding sites were prepared. NMR and calorimetric titration experiments revealed that each of the three sites independently binds beta-cyclodextrin (beta-CD) or cucurbit[7]uril (CB7) units to form binary host-guest complexes with 1:3 stoichiometry. The association constants for the single binding site for beta-CD and CB7 were determined using titration calorimetry and are in the order of 10(5) and 10(9-10) dm(3) mol(-1), respectively. In addition, both guests were able to form ternary systems with beta-CD and CB7 in ratios of 1:1:2 and 1:2:1, respectively.