Interconversion between [5]pseudorotaxane and [3]pseudorotaxane by pasting/detaching two axle molecules

摘要

An acceptor-donor-acceptor-type linear molecule 1~(2+) containing one electron-rich naphthoxy (NP) unit and two monocharged viologen (MCV) units was synthesized. Through the noncovalent interaction of cucurbit[8]uril (CB[8]) with one NP and one MCV in 1~(2+), we first obtained a [2]pseudorotaxane ([1~(2+)]?CB[8]), and the excess CB[8] included simultaneously the two bare MCV units of two [2]pseudorotaxanes to form a [5]pseudorotaxane ([1~(2+)]_2?[CB[8]]_3). Its transformation to [3]pseudorotaxane was achieved through detaching the two axle molecules in the presence of acid, and then the addition of base may result in a reversible switch between two different pseudorotaxanes. This novel methodology elongating reversibly linear molecules by noncovalent interactions will benefit the development of stimuli-responsive functional molecular devices.