Aromatic gain in a supramolecular polymer

V.S. Talens, P. Englebienne, Thuat Trinh, W.E.M. Noteborn, I.K. Voets, R.E. Kieltyka

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Abstract

The synergy of aromatic gain and hydrogen bonding in a supramolecular polymer is explored. Partially aromatic bis(squaramide) bolaamphiphiles were designed to self-assemble through a combination of hydrophobic, hydrogen-bonding, and aromatic effects into stiff, high-aspect-ratio fibers. UV and IR spectroscopy show electron delocalization and geometric changes within the squaramide ring indicative of strong hydrogen bonding and aromatic gain of the monomer units. The aromatic contribution to the interaction energy was further supported computationally by nucleus-independent chemical shift (NICS) and harmonic oscillator model of aromaticity (HOMA) indices, demonstrating greater aromatic character upon polymerization: at least 30 % in a pentamer. The aromatic gain–hydrogen bonding synergy results in a significant increase in thermodynamic stability and a striking difference in aggregate morphology of the bis(squaramide) bolamphiphile compared to isosteres that cannot engage in this effect.
Original languageEnglish
Pages (from-to)10502-10506
JournalAngewandte Chemie - International Edition
Volume54
Issue number36
DOIs
Publication statusPublished - 1 Sep 2015

Keywords

  • aromaticity
  • non-covalent interactions
  • self-assembly
  • squaramides
  • supramolecular polymers

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