Molecular Packing of Amphiphilic Nanosheets Resolved by X-ray Scattering

Boris Harutyunyan, Adam Dannenhoffer, Sumit Kewalramani, Taner Aytun, Daniel J. Fairfield, Samuel I. Stupp, Michael J. Bedzyk*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Molecular packing in light harvesting 2D assemblies of photocatalytic materials is a critical factor for solar-to-fuel conversion efficiency. However, structure-function correlations have yet to be fully established. This is partly due to the difficulties in extracting the molecular arrangements from the complex 3D powder averaged diffraction patterns of 2D lattices, obtained via in situ wide-angle X-ray scattering. Here, we develop a scattering theory formalism and couple it with a simple geometrical model for the molecular shape of chromophore 9-methoxy-N-(sodium hexanoate)perylene-3,4-dicarboximide (MeO-PMI) used in our study. This generally applicable method fully reproduces the measured diffraction pattern including the asymmetric line shapes for the Bragg reflections and yields the molecular packing arrangement within a 2D crystal structure with a remarkable degree of detail. We find an approximate edge-centered herringbone structure for the PMI fused aromatic rings and ordering of the carboxypentyl chains above and below the nanosheets. Such a packing arrangement differs from the more symmetric face-to-face orientation of the unsubstituted PMI rings. This structural difference is correlated to our measurement of the reduced catalytic performance of MeO-PMI nanosheets as compared to the mesoscopically similar unsubstituted PMI assemblies.

Original languageEnglish (US)
Pages (from-to)1047-1054
Number of pages8
JournalJournal of Physical Chemistry C
Issue number2
StatePublished - Jan 19 2017

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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