Hughes, Ashlea R 
ORCID: 0000-0001-9625-6921, Liu, Ming ORCID: 0000-0003-0008-1480, Paul, Subhradip, Cooper, Andrew I ORCID: 0000-0003-0201-1021 and Blanc, Frederic ORCID: 0000-0001-9171-1454
(2021)
Dynamics in Flexible Pillar[<i>n</i>]arenes Probed by Solid-State NMR.
JOURNAL OF PHYSICAL CHEMISTRY C, 125 (24).
pp. 13370-13381.
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Abstract
Pillar[<i>n</i>]arenes are supramolecular assemblies that can perform a range of technologically important molecular separations which are enabled by their molecular flexibility. Here, we probe dynamical behavior by performing a range of variable-temperature solid-state NMR experiments on microcrystalline perethylated pillar[<i>n</i>]arene (<i>n</i> = 5, 6) and the corresponding three pillar[6]arene xylene adducts in the 100-350 K range. This was achieved either by measuring site-selective motional averaged <sup>13</sup>C <sup>1</sup>H heteronuclear dipolar couplings and subsequently accessing order parameters or by determining <sup>1</sup>H and <sup>13</sup>C spin-lattice relaxation times and extracting correlation times based on dipolar and/or chemical shift anisotropy relaxation mechanisms. We demonstrate fast motional regimes at room temperature and highlight a significant difference in dynamics between the core of the pillar[<i>n</i>]arenes, the protruding flexible ethoxy groups, and the adsorbed xylene guest. Additionally, unexpected and sizable <sup>13</sup>C <sup>1</sup>H heteronuclear dipolar couplings for a quaternary carbon were observed for <i>p</i>-xylene adsorbed in pillar[6]arene only, indicating a strong host-guest interaction and establishing the <i>p</i>-xylene location inside the host, confirming structural refinements.
| Item Type: | Article |
|---|---|
| Divisions: | Faculty of Science and Engineering > School of Physical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 16 Jun 2021 08:52 |
| Last Modified: | 17 Oct 2023 19:31 |
| DOI: | 10.1021/acs.jpcc.1c02046 |
| Open Access URL: | https://pubs.acs.org/doi/10.1021/acs.jpcc.1c02046 |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3126531 |
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