Understanding the effect of fluorocarbons in aqueous supramolecular polymerization: Ultrastrong noncovalent binding and cooperativity

Elisha Krieg, Haim Weissman, Eyal Shimoni, Alona Baris, Boris Rybtchinski

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Achieving supramolecular polymerization based on strong yet reversible bonds represents a significant challenge. A solution may be offered by perfluoroalkyl groups, which have remarkable hydrophobicity. We tested the idea that a perfluorooctyl chain attached to a perylene diimide amphiphile can dramatically enhance the strength of supramolecular bonding in aqueous environments. Supramolecular structures and polymerization thermodynamics of this fluorinated compound (1-F) were studied in comparison to its non-fluorinated analogue (1-H). Depending on the amount of organic cosolvent, 1-F undergoes cooperative or isodesmic aggregation. The switching between two polymerization mechanisms results from a change in polymer structure, as observed by cryogenic electron microscopy. 1-F showed exceptionally strong noncovalent binding, with the largest directly measured association constant of 1.7 × 109 M-1 in 75:25 water/THF mixture (v/v). In pure water, the association constant of 1-F is estimated to be at least in the order of 1015 M-1 (based on extrapolation), 3 orders of magnitude larger than that of 1-H. The difference in aggregation strength between 1-F and 1-H can be explained solely on the basis of the larger surface area of the fluorocarbon group, rather than a unique nature of fluorocarbon hydrophobicity. However, differences in aggregation mechanism and cooperativity exhibited by 1-F appear to result from specific fluorocarbon conformational rigidity.

Original languageEnglish
Pages (from-to)9443-9452
Number of pages10
JournalJournal of the American Chemical Society
Volume136
Issue number26
DOIs
Publication statusPublished - Jul 2 2014

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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