Controlled self-assembly of hexa-peri-hexabenzocoronenes in solution

Jishan Wu, Andreas Fechtenkötter, Jürgen Gauss, Mark D. Watson, Marcel Kastler, Chrys Fechtenkötter, Manfred Wagner, Klaus Müllen

Research output: Contribution to journalArticlepeer-review

157 Scopus citations

Abstract

Disc-shaped hexa-peri-hexabenzocoronenes (HBCs) peripherally substituted by flexible dodecyl chains (molecule 1) or rigid polyphenylene dendrons (molecules 2a,b and 3) were efficiently synthesized. Steric hindrance arising from the substituents, from less hindered dodecyl to bulky dendrons, was utilized to program the self-assembly of the HBC cores in solution. The high tendency of the hexadodecyl-substituted HBC 1 to aggregate was determined by concentration and temperature-dependent 1H NMR spectroscopic measurements and nonlinear least-squares analysis of the experimental data. The rigid dendrons in molecule 2a suppress the π-π interactions of the HBC cores to a certain extent, and a slow (with respect to the NMR time scale) monomer-dimer equilibrium is observed. This unique equilibrium was further controlled by temperature, concentration, and solvent to afford discrete monomeric or dimeric species. Further structural modifications such as the replacement of dodecyl groups in 2a with hydrogen atoms resulted in a stable dimer structure in 2b due to diminished steric hindrance, as supported by quantum chemical calculations. "Moving" the dendron arms closer to the HBC core gives molecule 3, which exists only as a nonaggregated monomer. UV-vis absorption and fluorescence spectra of these discrete species revealed obvious differences in their electronic and optoelectronic properties which can be explained by the existence or absence of π-π interactions.

Original languageEnglish
Pages (from-to)11311-11321
Number of pages11
JournalJournal of the American Chemical Society
Volume126
Issue number36
DOIs
StatePublished - Sep 15 2004

ASJC Scopus subject areas

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

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