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This content will become publicly available on December 26, 2018

Title: Ultrafast rotation in an amphidynamic crystalline metal organic framework

Amphidynamic crystals are an emergent class of condensed phase matter designed with a combination of lattice-forming elements linked to components that display engineered dynamics in the solid state. Here, we address the design of a crystalline array of molecular rotors with inertial diffusional rotation at the nanoscale, characterized by the absence of steric or electronic barriers. We solved this challenge with 1,4-bicyclo[2.2.2]octane dicarboxylic acid (BODCA)-MOF, a metal-organic framework (MOF) built with a high-symmetry bicyclo[2.2.2]octane dicarboxylate linker in a Zn 4O cubic lattice. Using spin-lattice relaxation 1H solid-state NMR at 29.49 and 13.87 MHz in the temperature range of 2.3–80 K, we showed that internal rotation occurs in a potential with energy barriers of 0.185 kcal mol -1. These results were confirmed with 2H solid-state NMR line-shape analysis and spin-lattice relaxation at 76.78 MHz obtained between 6 and 298 K, which, combined with molecular dynamics simulations, indicate that inertial diffusional rotation is characterized by a broad range of angular displacements with no residence time at any given site. Furthermore, the ambient temperature rotation of the bicyclo[2.2.2]octane (BCO) group in BODCA-MOF constitutes an example where engineered rotational dynamics in the solid state are as fast as they would be in a high-densitymore » gas or in a low-density liquid phase.« less
Authors:
 [1] ;  [2] ; ORCiD logo [3] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1]
  1. Univ. of California, Los Angeles, CA (United States)
  2. Univ. of Central Florida, Orlando, FL (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Report Number(s):
PNNL-SA-125469
Journal ID: ISSN 0027-8424; 45292; KP1704020
Grant/Contract Number:
AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 52; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; Environmental Molecular Sciences Laboratory; metal-organic frameworks; molecular rotors; molecular machines; smart materials; amphidynamic crystals
OSTI Identifier:
1427926