A versatile synthetic strategy, which was conceived and employed to prepare doubly threaded, bistable [c2]dalsy chain compounds, Is described. Propargyl and 1-pentenyl groups have been grafted onto the stoppers of [c2]dalsy chain molecules obtained using a template-directed synthetic protocol. Such [c2]dalsy chain molecules undergo reversible extension and contraction upon treatment with acid and base, respectively. The dialkyne-functionalized [c2]dalsy chain (AA) was subjected to an [AA+BB] type polymerization with an appropriate diazide (BB) to afford a linear, mechanically Interlocked, main-chain polymer. The macromolecular properties of this polymer were characterized by chronocoulometry, size exclusion chromatography, and static light-scattering analysis. The acid-base switching properties of both the monomers and the polymer have been studied In solution, using H NMR spectroscopy, UV/vls absorption spectroscopy, and cyclic voltammetry. The experimental results demonstrate that the functionalized [c2]daisy chains, along with their polymeric derivatives, undergo quantitative, efficient, and fully reversible switching processes In solution. Kinetics measurements demonstrate that the acid/base-promoted extension/contraction movements of the polymeric [c2]daisy chain are actually faster than those of Its monomeric counterpart. These observations open the door to correlated molecular motions and to changes In material properties. 2009 American Chemical Society.
ASJC Scopus subject areas
- Colloid and Surface Chemistry