Twisted Cucurbit[n]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)(4)Cd(H2O)(4)tQ[13]}center dot 2.5[CdCl4]-65H(2)O and {Cd-0.5(H2O)(2)tQ[15]}center dot [CdCl4]center dot 47H(2)O. 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 to[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.