Supramolecular Packing Controls H2 Photocatalysis in Chromophore Amphiphile Hydrogels

Adam S. Weingarten, Roman V. Kazantsev, Liam C. Palmer, Daniel J. Fairfield, Andrew R. Koltonow, Samuel I Stupp

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

Light harvesting supramolecular assemblies are potentially useful structures as components of solar-to-fuel conversion materials. The development of these functional constructs requires an understanding of optimal packing modes for chromophores. We investigated here assembly in water and the photocatalytic function of perylene monoimide chromophore amphiphiles with different alkyl linker lengths separating their hydrophobic core and the hydrophilic carboxylate headgroup. We found that these chromophore amphiphiles (CAs) self-assemble into charged nanostructures of increasing aspect ratio as the linker length is increased. The addition of salt to screen the charged nanostructures induced the formation of hydrogels and led to internal crystallization within some of the nanostructures. For linker lengths up to seven methylenes, the CAs were found to pack into 2D crystalline unit cells within ribbon-shaped nanostructures, whereas the nine methylene CAs assembled into long nanofibers without crystalline molecular packing. At the same time, the different molecular packing arrangements after charge screening led to different absorbance spectra, despite the identical electronic properties of all PMI amphiphiles. While the crystalline CAs formed electronically coupled H-aggregates, only CAs with intermediate linker lengths showed evidence of high intermolecular orbital overlap. Photocatalytic hydrogen production using a nickel-based catalyst was observed in all hydrogels, with the highest turnovers observed for CA gels having intermediate linker lengths. We conclude that the improved photocatalytic performance of the hydrogels formed by supramolecular assemblies of the intermediate linker CA molecules likely arises from improved exciton splitting efficiencies due to their higher orbital overlap.

Original languageEnglish
Pages (from-to)15241-15246
Number of pages6
JournalJournal of the American Chemical Society
Volume137
Issue number48
DOIs
Publication statusPublished - Dec 9 2015

Fingerprint

Amphiphiles
Hydrogels
Nanostructures
Photocatalysis
Chromophores
Perylene
Nanofibers
Crystallization
Nickel
Crystalline materials
Hydrogen
Salts
Gels
Light
Water
Hydrogen production
Excitons
Electronic properties
Aspect ratio
Screening

ASJC Scopus subject areas

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

Cite this

Weingarten, A. S., Kazantsev, R. V., Palmer, L. C., Fairfield, D. J., Koltonow, A. R., & Stupp, S. I. (2015). Supramolecular Packing Controls H2 Photocatalysis in Chromophore Amphiphile Hydrogels. Journal of the American Chemical Society, 137(48), 15241-15246. https://doi.org/10.1021/jacs.5b10027

Supramolecular Packing Controls H2 Photocatalysis in Chromophore Amphiphile Hydrogels. / Weingarten, Adam S.; Kazantsev, Roman V.; Palmer, Liam C.; Fairfield, Daniel J.; Koltonow, Andrew R.; Stupp, Samuel I.

In: Journal of the American Chemical Society, Vol. 137, No. 48, 09.12.2015, p. 15241-15246.

Research output: Contribution to journalArticle

Weingarten, AS, Kazantsev, RV, Palmer, LC, Fairfield, DJ, Koltonow, AR & Stupp, SI 2015, 'Supramolecular Packing Controls H2 Photocatalysis in Chromophore Amphiphile Hydrogels', Journal of the American Chemical Society, vol. 137, no. 48, pp. 15241-15246. https://doi.org/10.1021/jacs.5b10027
Weingarten, Adam S. ; Kazantsev, Roman V. ; Palmer, Liam C. ; Fairfield, Daniel J. ; Koltonow, Andrew R. ; Stupp, Samuel I. / Supramolecular Packing Controls H2 Photocatalysis in Chromophore Amphiphile Hydrogels. In: Journal of the American Chemical Society. 2015 ; Vol. 137, No. 48. pp. 15241-15246.
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