Tailoring the cavities of hydrogen-bonded amphidynamic crystals using weak contacts: towards faster molecular machines
- Univ. Nacional Autonoma de Mexico (UNAM) (Mexico)
- Univ. of California, Los Angeles, CA (United States)
- Centro de Investigación y de Estudios Avanzados, Mérida (Mexico)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Univ. Nacional Autonoma de Mexico (UNAM) (Mexico)
This work describes the use of C–H∙∙∙F–C contacts in the solid-state from the stator towards the rotator to fine-tune their internal motion, by constructing a set of interactions that generate close-fitting cavities in three supramolecular rotors 1–3I. The crystal structures of these rotors, determined by synchrotron radiation experiments at different temperatures, show the presence of such C–H∙∙∙F–C contacts between extended carbazole stators featuring fluorinated phenyl rings and the 1,4-diazabicyclo[2.2.2]octane (DABCO) rotator. According to the 2H NMR results, using deuterated samples, and periodic density functional theory computations, the rotators experience fast angular displacements (preferentially 120° jumps) due to their low rotational activation energies (Ea = 0.8–2.0 kcal mol-1). The higher rotational barrier for 1 (2.0 kcal mol-1) is associated with a larger number of weak C–H∙∙∙F–C contacts generated by the stators. This strategy offers the possibility to explore the correlation among weak intermolecular forces, cavity shape, and internal dynamics, which has strong implications in the design of future fine-tuned amphidynamic crystals.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES), Scientific User Facilities Division
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1811506
- Journal Information:
- Chemical Science, Vol. 12, Issue 6; ISSN 2041-6520
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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