title: Crowned dendrimers: pH-responsive pseudorotaxane formation.
abstract: With the end goal of incorporating the unique structural and physical properties of dendrimers into supramolecular assemblies, bis(m-phenylene)-32-crown-10-functionalized poly(propyleneimine) dendrimers of the first and third generations have been synthesized and their interaction with paraquat diol has been investigated. Using (1)H NMR, we determined that binding to the 4 or 16 crown ether sites occurred in an anti-cooperative fashion, most likely a result of steric influences. Upon protonation of the tertiary amines in the dendritic interior, binding became independent, i.e., statistical, and the average apparent association constant increased by nearly 5-fold; this effect is attributed to rigidification of the dendrimer, which makes its binding sites more accessible and less crowded.
authors.affiliation: Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0212, USA.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Jones
authors.forename: William S
authors.initials: WS
authors.lastname: Bryant
authors.forename: Anton W
authors.initials: AW
authors.lastname: Bosman
authors.forename: Rene A J
authors.initials: RA
authors.lastname: Janssen
authors.forename: E W
authors.initials: EW
authors.lastname: Meijer
authors.forename: Harry W
authors.initials: HW
authors.lastname: Gibson