The cucurbit[n]uril (CB[n]) family of macrocycles occupies a prominent role in molecular recognition and self-assembly studies despite the current inability to access specific cucurbit[n]uril homologues, derivatives, and analogues by straightforward tailor-made synthetic procedures. In this paper, we explore an approach that circumvents the challenges posed by the tailor-made synthesis of macrocyclic CB[n] by preparing 1, which functions as an acyclic CB[6] congener. The o-xylylene connections to the glycoluril rings preorganize 1 into the (a,a,a,a)-1 conformation required for binding and reduce its tendency to undergo self-association. We surveyed the binding properties of 1 toward 16 amines (K(a)

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Multi-membered N-heterocycles R 0690Acyclic Congener of Cucurbituril: Synthesis and Recognition Properties. -The recognition properties of the acyclic congener (I) are similar to those of cucurbituril. It undergoes complexation with a range of alkaneammonium and alkanediammonium ions in water, it exhibits length-dependent selectivity, and is competitively bound by alkali metal cations in phosphate buffer. Its binding affinity is only 180-fold lower than that of cucurbituril. -(BURNETT, C. A.; WITT, D.; FETTINGER, J. C.; ISAACS*, L.; J. Org. Chem. 68 (2003) 16, 6184-6191; Dep. Chem. Biochem., Univ. Md.,

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