Abstract
The energy landscape of a supramolecular material can include different molecular packing configurations that differ in stability and function. We report here on a thermally driven crystalline order transition in the landscape of supramolecular nanostructures formed by charged chromophore amphiphiles in salt-containing aqueous solutions. An irreversible transition was observed from a metastable to a stable crystal phase within the nanostructures. In the stable crystalline phase, the molecules end up organized in a short scroll morphology at high ionic strengths and as long helical ribbons at lower salt content. This is interpreted as the result of the competition between electrostatic repulsive forces and attractive molecular interactions. Only the stable phase forms charge-transfer excitons upon exposure to visible light as indicated by absorbance and fluorescence features, second-order harmonic generation microscopy, and femtosecond transient absorbance spectroscopy. Interestingly, the supramolecular reconfiguration to the stable crystalline phase nanostructures enhances photosensitization of a proton reduction catalyst for hydrogen production.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 6120-6127 |
| Number of pages | 8 |
| Journal | Journal of the American Chemical Society |
| Volume | 139 |
| Issue number | 17 |
| DOIs | |
| State | Published - May 3 2017 |
Funding
This work was supported as part of the Argonne−Northwestern Solar Energy Research (ANSER) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0001059. AFM, SHG, and powder XRD experiments were also supported by the Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, of the U.S. Department of Energy under Award No. DE-FG02- 00ER45810. Use of the Advanced Photon Source (APS) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357. Variable-temperature X-ray experiments were performed at the DuPont−Northwestern−Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS). DND-CAT is supported by Northwestern University, E.I. DuPont de Nemours and Co., and The Dow Chemical Company. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357. WAXS experiments conducted at BioCARS Sector 14 at the APS were supported by grants from the National Center for Research Resources (5P41RR007707) and the National Institute of General Medical Sciences (8P41GM103543) from the National Institutes of Health. GIXS data were collected at Sector 8-IDE of APS. We thank the Biological Imaging Facility (BIF) at Northwestern for the use of TEM equipment, the Electron Probe Instrumentation Center (EPIC) and Keck-II facilities of the Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) center for the use of SEM and XPS/UPS equipment. NMR and MS equipment at the Integrated Molecular Structure Education and Research Center (IMSERC) was supported by the National Science Foundation under CHE-9871268. The NUANCE Center is supported by the International Institute for Nanotechnology, MRSEC (NSF DMR-1121262), the Keck Foundation, the State of Illinois, and Northwestern University. The energy landscape analysis was supported by by the Center for Bio-Inspired Energy Sciences (CBES), an Energy Frontiers Research Center (EFRC) funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under award number DE-SC0000989.
ASJC Scopus subject areas
- Catalysis
- General Chemistry
- Biochemistry
- Colloid and Surface Chemistry
