pH-Regulated Selectivity in Supramolecular Polymerizations: Switching between Co- and Homopolymers [feedly]

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pH-Regulated Selectivity in Supramolecular Polymerizations: Switching between Co- and Homopolymers
// ChemEurJ

Abstract

A strategy is presented to regulate the selectivity in aqueous supramolecular polymerizations by changes in pH. In neutral buffered conditions, oppositely charged phenylalanine-based dendritic peptide amphiphiles self-assemble into (AB)_n alternating copolymers of low polydispersity when mixed in a 1:1 comonomer feed ratio. Via pH switch of the glutamic acid and lysine side chains, attractive Coulomb interactions in the coassembled materials are screened and selective polymerization occurs to form (A)_n homopolymers of the acidic comonomer at low pH and (B)_n homopolymers of the basic comonomer at high pH, while the complementary comonomer is released during the transition. Reversible switching is demonstrated between these three different polymeric states, which were characterized by CD and fluorescence spectroscopy, using a peptide based minimalistic fluorophore/quencher pair, and transmission electron microscopy.

Switchcraft: A strategy to regulate the selectivity in aqueous supramolecular polymerizations is presented. In neutral buffer, oppositely charged dendritic peptide amphiphiles selectively self-assemble into alternating copolymers. At high and low pH, the formation of either the basic or acidic homopolymer occurs while the complementary comonomer is released. The transition between these three different polymeric states is fully reversible and can be switched multiple times.

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B.Osmialowski