Photophysical pore control in an azobenzene-containing metal-organic framework

Jonathan W. Brown*, Bryana L. Henderson, Matthew D. Kiesz, Adam C. Whalley, William Morris, Sergio Grunder, Hexiang Deng, Hiroyasu Furukawa, Jeffrey I. Zink, J. Fraser Stoddart, Omar M. Yaghi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

162 Scopus citations


The synthesis and structure of an azobenzene functionalized isoreticular metal-organic framework (azo-IRMOF-74-III) [Mg2(C26H16O6N2)] are described and the ability to controllably release a guest from its pores in response to an external stimulus has been demonstrated. Azo-IRMOF-74-III is an isoreticular expansion of MOF-74 with an etb topology and a 1-D hexagonal pore structure. The structure of azo-IRMOF-74-III is analogous to that of MOF-74, as demonstrated by powder X-ray diffraction, with a surface area of 2410 m2 g−1 BET. Each organic unit within azo-IRMOF-74-III is decorated with a photoswitchable azobenzene unit, which can be toggled between its cis and trans conformation by excitation at 408 nm. When propidium iodide dye was loaded into the MOF, spectroscopic studies showed that no release of the luminescent dye was observed under ambient conditions. Upon irradiation of the MOF at 408 nm, however, the rapid wagging motion inherent to the repetitive isomerization of the azobenzene functionality triggered the release of the dye from the pores. This light-induced release of cargo can be modulated between an on and an off state by controlling the conformation of the azobenzene with the appropriate wavelength of light. This report highlights the ability to capture and release small molecules and demonstrates the utility of self-contained photo-active switches located inside highly porous MOFs.

Original languageEnglish (US)
Pages (from-to)2858-2864
Number of pages7
JournalChemical Science
Issue number7
StatePublished - Jun 4 2013

ASJC Scopus subject areas

  • Chemistry(all)

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