Twisted Cucurbit[<i>n</i>]urils

Two new twisted cucurbiturils, cucurbit[13]­uril (tQ­[13]) and cucurbit[15]­uril (tQ­[15]), have been synthesized and separated, and their structures have been confirmed by NMR spectroscopy and MALDI-TOF mass spectrometry together with the X-ray structures of two new complexes, {Dy­(H2O)4Cd­(H2O)4tQ­[13]}·2.5­[CdCl4]·65H2O and {Cd0.5(H2O)2tQ­[15]}·[CdCl4]·47H2O. tQ­[15] is the largest cucurbit­[n]­uril (Q­[n]) in the Q­[n] family reported to date. The X-ray diffraction studies of both complexes indicated that these large tQ­[n]­s effectively exhibit two different cavities–a central cavity and two side cavities. Preliminary host–guest behavior by each of the new systems was investigated by NMR studies.