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Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
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...
Autores principales: | , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Royal Society of Chemistry
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5477839/ https://www.ncbi.nlm.nih.gov/pubmed/28694954 http://dx.doi.org/10.1039/c6sc05058a |
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author | Kaabel, Sandra Adamson, Jasper Topić, Filip Kiesilä, Anniina Kalenius, Elina Öeren, Mario Reimund, Mart Prigorchenko, Elena Lõokene, Aivar Reich, Hans J. Rissanen, Kari Aav, Riina |
author_facet | Kaabel, Sandra Adamson, Jasper Topić, Filip Kiesilä, Anniina Kalenius, Elina Öeren, Mario Reimund, Mart Prigorchenko, Elena Lõokene, Aivar Reich, Hans J. Rissanen, Kari Aav, Riina |
author_sort | Kaabel, Sandra |
collection | PubMed |
description | 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 SbF(6) (–) ≈ PF(6) (–) > ReO(4) (–) > ClO(4) (–) > SCN(–) > BF(4) (–) > HSO(4) (–) > CF(3)SO(3) (–) 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 SbF(6) (–) anion, with an association constant of 2.5 × 10(5) 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. |
format | Online Article Text |
id | pubmed-5477839 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | Royal Society of Chemistry |
record_format | MEDLINE/PubMed |
spelling | pubmed-54778392017-07-10 Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution Kaabel, Sandra Adamson, Jasper Topić, Filip Kiesilä, Anniina Kalenius, Elina Öeren, Mario Reimund, Mart Prigorchenko, Elena Lõokene, Aivar Reich, Hans J. Rissanen, Kari Aav, Riina Chem Sci Chemistry 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 SbF(6) (–) ≈ PF(6) (–) > ReO(4) (–) > ClO(4) (–) > SCN(–) > BF(4) (–) > HSO(4) (–) > CF(3)SO(3) (–) 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 SbF(6) (–) anion, with an association constant of 2.5 × 10(5) 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. Royal Society of Chemistry 2017-03-01 2016-11-30 /pmc/articles/PMC5477839/ /pubmed/28694954 http://dx.doi.org/10.1039/c6sc05058a Text en This journal is © The Royal Society of Chemistry 2016 http://creativecommons.org/licenses/by/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution 3.0 Unported License (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Chemistry Kaabel, Sandra Adamson, Jasper Topić, Filip Kiesilä, Anniina Kalenius, Elina Öeren, Mario Reimund, Mart Prigorchenko, Elena Lõokene, Aivar Reich, Hans J. Rissanen, Kari Aav, Riina Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution |
title | Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
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title_full | Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
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title_fullStr | Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
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title_full_unstemmed | Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
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title_short | Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
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title_sort | chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution |
topic | Chemistry |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5477839/ https://www.ncbi.nlm.nih.gov/pubmed/28694954 http://dx.doi.org/10.1039/c6sc05058a |
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