Interactions of α, ω-alkyldiammonium with inverted cucurbit[6]uril

Molecular interactions between an inverted cucurbit[6]uril ( i Q[6]) with α , ω -alkyldiammonium guests (H 3 N(CH 2 ) x NH 3 Cl 2 , x = 2, 4, 6, 8, 10, and 12 named 1 – 6 ) were investigated in aqueous and acidic solutions by various techniques. 1 H NMR spectroscopy revealed that only compounds 3 and 4 underwent an equilibrium interaction with the i Q[6] host, with association constants in acidic solution of ~83 and ~41 L mol −1 , respectively, while the other guests showed no obvious interaction. Only two host–guest interaction systems gave rise to single crystals in the presence of polychloride transition metal anions as structure-directing agents. X-ray diffraction revealed that guests 1 and 3 interacted with i Q[6] through portal and cavity interactions, respectively.