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pH‐Regulated Selectivity in Supramolecular Polymerizations: Switching between Co‐ and Homopolymers
Author(s) -
Frisch Hendrik,
Nie Yan,
Raunser Stefan,
Besenius Pol
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201406281
Subject(s) - comonomer , copolymer , supramolecular chemistry , chemistry , polymer chemistry , selectivity , polymerization , aqueous solution , amphiphile , fluorophore , dispersity , photochemistry , combinatorial chemistry , fluorescence , organic chemistry , polymer , molecule , catalysis , physics , quantum mechanics
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.