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

Abstract

(formula presented) Dibenzylammonium (DBA+) ions thread through the cavity of tribenzo[27]crown-9 (TB27C9) to generate [2]pseudorotaxanes that are stabilized principally by hydrogen-bonding interactions. The stabilities and complexation kinetics associated with these pseudorotaxanes depend markedly on the nature of the substituents situated on the phenyl rings of the DBA+ ions. For example, the complex formed between TB27C9 and the DBA+ ion bearing electron-withdrawing P-CO2Me substituents is stronger than that obtained from TB27C9 and the "parent", unsubstituted DBA+ ion itself. Furthermore, the "parent" complex equilibrates much more rapidly with its uncomplexed components than do the complexes generated from TB27C9 and substituted DBA ions.