Angewandte Chemie International Edition
10.1002/anie.201906606
compared to the Z-rich shell, demonstrating that the shell is
functioning as a kinetic barrier for the diffusion of guests into the
pores. A similar, yet less pronounced initial difference was also
observed in the release experiments. Uptake experiments with
two other guests, methylene blue and 8-hydroxypyrene-1,3,6-
trisulfonic acid trisodium salt (HPTS), were also performed and
show a similar uptake behavior for the different setups. The
uptake of methylene blue is much faster, presumably due to its
smaller size as compared to the pyrene derivatives, yet the
modulation upon photoisomerizing the shell is less pronounced.
The opposite can be observed for the larger HPTS guest (see
Figures S24 and S25).
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In conclusion we have developed a UiO-68 based two-
component core-shell MOF composed of a non-functionalized
interior for storage of guest molecules and a light-responsive
outer shell acting as a gate for their uptake and release in
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Our findings demonstrate that the azobenzene-ligand shell is
acting as a photoresponsive kinetic barrier for the diffusion in
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(
and out) of the MOF interior. In a next step, we are currently
aiming at implementing catalytically active cores to exploit our
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access of substrates and thus influence the outcome of the
reaction.
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Acknowledgements
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The authors thank Jana Hildebrandt and Jutta Schwarz for up-
[11] Review: O. Karagiaridi, W. Bury, J. E. Mondloch, J. T. Hupp, O. K. Farha,
azo
core
Angew. Chem. Int. Ed. 2014, 53, 4530-4540.
scaling the synthesis of linkers L and L , Dr. Matthias Karg
for pXRD measurements, Dr. Björn Kobin for TGA, Dr. Lutz
Grubert for electrochemistry, and Svante Ihrig for the design of
the TOC figure. A.G.-H. is indebted to the Alexander von
Humboldt-Foundation and the FQRNT for providing postdoctoral
[12] Z. Wang, K. Müller, M. Valášek, S. Grosjean, S. Bräse, C. Wöll, M. Mayor,
L. Heinke, J. Phys. Chem. C 2018, 122, 19044−19050.
[13] M. V. Peters, PhD thesis, Humboldt-Universität zu Berlin, 2008.
[14] A. Schaate, P. Roy, A. Godt, J. Lippke, F. Waltz, M. Wiebcke, P. Behrens,
fellowships.
Generous
support
by
the
Deutsche
Chem. Eur. J. 2011, 17, 6643–6651.
Forschungsgemeinschaft (Projektnummer 182087777 - SFB 951
and BL 1269 “Visimat”), the Daimler Benz-Foundation (via 32-
0
2
2/14) as well as the European Research Council (via ERC-
012-StG_308117 “Light4Function”) is gratefully acknowledged.
Conflict of Interests
The authors declare no conflict of interest.
Keywords: azobenzene • guest uptake/release • metal-organic
frameworks • photochromism • visible light
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