Tribenzo[27]crown-9: A new ring for dibenzylammonium rods

[GRAPHICS] Dibenzylammonium (DBA(+)) ions thread through the cavity of tribenzo[27]cro wn-9 (TB27C9) to generate [2]pseudorotaxanes that are stabilized principall y by hydrogen bonding interactions. The stabilities and complexation kineti cs associated with these pseudorotaxanes depend markedly on the nature of t he substituents situated on the phenyl rings of the DBA(+) ions. For exampl e, the complex formed between TB27C9 and the DBA(+) ion bearing electron wi thdrawing p-CO2Me substituents is stronger than that obtained from TB27C9 a nd the "parent", unsubstituted DBA(+) ion itself. Furthermore, the "parent" complex equilibrates much more rapidly with its uncomplexed components tha n do the complexes generated from TB27C9 and substituted DBA(+) ions.