A1 Journal article (refereed)
Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution (2017)


Kaabel, Sandra; Adamson, Jasper; Topic, Filip; Kiesilä, Anniina; Kalenius, Elina; Öeren, Mario; Reimund, Mart; Prigorchenko, Elena; Lõokene, Aivar; Reich, Hans J.; Rissanen, Kari; Aav, Riina (2017). Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution. Chemical Science, 8 (3), 2184-2190. DOI: 10.1039/C6SC05058A


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Publication details

All authors or editors: Kaabel, Sandra; Adamson, Jasper; Topic, Filip; Kiesilä, Anniina; Kalenius, Elina; Öeren, Mario; Reimund, Mart; Prigorchenko, Elena; Lõokene, Aivar; Reich, Hans J.; et al.

Journal or series: Chemical Science

ISSN: 2041-6520

eISSN: 2041-6539

Publication year: 2017

Volume: 8

Issue number: 3

Pages range: 2184-2190

Publisher: Royal Society of Chemistry

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1039/C6SC05058A

Open Access: Publication published in an open access channel

Publication channel open access:

Publication open access:

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/66509


Abstract

A novel eight-membered macrocycle of the hemicucurbit[n]uril family, chiral (all-R)-cyclohexanohemicucurbit[8]uril (cycHC[8]) binds anions in a purely protic solvent with remarkable selectivity. The cycHC[8] portals open and close to fully encapsulate anions in a 1 : 1 ratio, resembling a molecular Pac-Man™. Comprehensive gas, solution and solid phase studies prove that the binding is governed by the size, shape and charge distribution of the bound anion. Gas phase studies show an order of SbF6− ≈ PF6− > ReO4− > ClO4− > SCN− > BF4− > HSO4− > CF3SO3− for anion complexation strength. An extensive crystallographic study reveals the preferred orientations of the anions within the octahedral cavity of cycHC[8] and highlights the importance of the size- and shape-matching between the anion and the receptor cavity. The solution studies show the strongest binding of the ideally fitting SbF6− anion, with an association constant of 2.5 × 105 M−1 in pure methanol. The symmetric, receptor cavity-matching charge distribution of the anions results in drastically stronger binding than in the case of anions with asymmetric charge distribution. Isothermal titration calorimetry (ITC) reveals the complexation to be exothermic and enthalpy-driven. The DFT calculations and VT-NMR studies confirmed that the complexation proceeds through a pre-complex formation while the exchange of methanol solvent with the anion is the rate-limiting step. The octameric cycHC[8] offers a unique example of template-controlled design of an electroneutral host for binding large anions in a competitive polar solvent.


Keywords: selectivity

Free keywords: macrocycles; hemicucurbituril; anion receptors


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Ministry reporting: Yes

Reporting Year: 2017

JUFO rating: 3


Last updated on 2021-15-03 at 13:32