Chiral Nanostructures from Helical Copolymer-Metal Complexes: Tunable Cation-π Interactions and Sergeants and Soldiers Effect
Abstract
Poly(phenylacetylene) (PPA) copolymers containing (R)- or (S)-MPA as minor chiral pendant can be forced to selectively adopt the right- o left-handed helix, in the presence of small amounts of Na+ or Ag+ (“Sergeants and Soldiers Effect”) by addition of a donor cosolvent. The helical sense depends exclusively on the chiral monomer/donor cosolvent ratio, and this allows a perfect on/off tuning of the helicity of the copolymer. When the amount of the donor cosolvent is low, the metal ion complex is stabilized by a cation–π interaction, which is selectively cleaved when the amount of cosolvent is higher. Macroscopically chiral nanospheres and nanotubes composed by helical copolymers with P or M helical sense are also described. Our results demonstrate that it is possible to obtain the two enantiomeric helical structures (P and M helicities) and the corresponding nanospheres and nanotubes from a single helical copolymer, by controlled activation/deactivation of the Sergeant and Soldiers Effect with a donor cosolvent.Keywords
Funding Information
- MEC (CTQ2012-33436, CTQ2012-31381, CTQ2014-61470-EXP)
- Xunta de Galicia (EM2013/0032, GRC2014/040)
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