Computational and NMR Studies on the Complexation of Lithium Ion to 8-Crown-4

Alex van der Ham, Thomas Hansen, Gerrit Lodder, Jeroen D.C. Codée, Trevor A. Hamlin, Dmitri V. Filippov*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Lithium ion selective crown ethers have been the subject of much research for a multitude of applications. Current research is aimed at structurally rigidifying crown ethers, as restructuring of the crown ether ring upon ion binding is energetically unfavorable. In this work, the lithium ion binding ability of the relatively rigid 8-crown-4 was investigated both computationally by density functional theory calculations and experimentally by 1H and 7Li NMR spectroscopy. Although both computational and experimental results showed 8-crown-4 to bind lithium ion, this binding was found to be weak compared to larger crown ethers. The computational analysis revealed that the complexation is driven by enthalpy rather than entropy, illustrating that rigidity is only of nominal importance. To elucidate the origin of the favorable interaction of lithium ion with crown ethers, activation strain analyses and energy decomposition analyses were performed pointing to the favorable interaction being mainly electrostatic in nature. 8-crown-4 presents the smallest crown ether reported to date capable of binding lithium ion, possessing two distinct conformations from which it is able to do so.

Original languageEnglish
Pages (from-to)2103-2109
Number of pages7
JournalChemPhysChem
Volume20
Issue number16
Early online date7 Jul 2019
DOIs
Publication statusPublished - 16 Aug 2019

Keywords

  • activation strain model
  • crown ethers
  • density functional calculations
  • lithium ion binding
  • perching complex

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