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Photoswitchable Sol–Gel Transitions and Catalysis Mediated by Polymer Networks with Coumarin‐Decorated Cu 24 L 24 Metal–Organic Cages as Junctions
Author(s) -
Oldenhuis Nathan J.,
Qin K. Peter,
Wang Shu,
Ye HongZhou,
Alt Eric A.,
Willard Adam P.,
Van Voorhis Troy,
Craig Stephen L.,
Johnson Jeremiah A.
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201913297
Subject(s) - polymer , supramolecular chemistry , covalent bond , cycloaddition , ethylene glycol , alkyne , catalysis , copper , polymer chemistry , materials science , photochemistry , metal , supramolecular polymers , chemistry , rhodium , crystallography , crystal structure , organic chemistry
Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre‐irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu 24 L 24 metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between Cu II , Cu I , and Cu 0 . The instability of the MOC junctions in the Cu I and Cu 0 states leads to network disassembly, forming Cu I /Cu 0 solutions, respectively, that are stable until re‐oxidation to Cu II and supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks.