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Title: Electrochemically addressable trisradical rotaxanes organized within a metal–organic framework

The organization of trisradical rotaxanes within the channels of a Zr6-based metal–organic framework (NU-1000) has been achieved postsynthetically by solvent-assisted ligand incorporation. Robust ZrIV–carboxylate bonds are forged between the Zr clusters of NU-1000 and carboxylic acid groups of rotaxane precursors (semirotaxanes) as part of this building block replacement strategy. Ultraviolet–visible–near-infrared (UV-Vis-NIR), electron paramagnetic resonance (EPR), and 1H nuclear magnetic resonance (NMR) spectroscopies all confirm the capture of redox-active rotaxanes within the mesoscale hexagonal channels of NU-1000. Cyclic voltammetry measurements performed on electroactive thin films of the resulting material indicate that redox-active viologen subunits located on the rotaxane components can be accessed electrochemically in the solid state. In contradistinction to previous methods, this strategy for the incorporation of mechanically interlocked molecules within porous materials circumvents the need for de novo synthesis of a metal–organic framework, making it a particularly convenient approach for the design and creation of solid-state molecular switches and machines. In conclusion, the results presented here provide proof-of-concept for the application of postsynthetic transformations in the integration of dynamic molecular machines with robust porous frameworks.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [1]
  1. Northwestern Univ., Evanston, IL (United States)
  2. Intel Labs, Santa Clara, CA (United States); King Abdulaziz City for Science and Technology., Riyadh (Saudi Arabia)
  3. Northwestern Univ., Evanston, IL (United States); King Abdulaziz Univ., Jeddah (Saudi Arabia)
Publication Date:
Grant/Contract Number:
AC05-06OR23100; FG87ER13808; W911NF-12-1-0130; FA9550-11-C-0028; DGE-0824162; CHE-1266201
Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 36; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Oak Ridge Associated Universities, Inc., Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; mechanically interlocked molecules; metal–organic framework; molecular switches; rotaxanes radicals
OSTI Identifier:
1235145
Alternate Identifier(s):
OSTI ID: 1348348