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ID 37976
file
creator
Boyarkin, Oleg V.
Kusaka, Ryoji
Rizzo, Thomas R.
subject
alkali metal ions
18-crown-6
15-crown-5
encapsulation
NDC
Chemistry
abstract
Electronic and vibrational spectra of benzo-15-crown-5 (B15C5) and benzo-18-crown-6 (B18C6) complexes with alkali metal ions, M+・B15C5 and M+・B18C6 (M = Li, Na, K, Rb and Cs), are measured using UV photodissociation (UVPD) and IR-UV double resonance spectroscopy in a cold, 22-pole ion trap. We determine the structure of conformers with the aid of density functional theory calculations. In the Na+・B15C5 and K+・B18C6 complexes, the crown ethers open the most and hold the metal ions at the center of the ether ring, demonstrating the optimum matching in size between the cavity of the crown ethers and the metal ions. For smaller ions, the crown ethers deform the ether ring to decrease the distance and increase the interaction between the metal ions and oxygen atoms; the metal ions are completely surrounded by the ether ring. In the case of larger ions, the metal ions are too large to enter the crown cavity and are positioned on it, leaving one of its sides open for further solvation. Thermochemistry data calculated on the basis of the stable conformers of the complexes suggest that the ion selectivity of crown ethers is controlled primarily by the enthalpy change for the complex formation in solution, which depends strongly on the complex structure.
description
This is a preprint of an article published by American Chemical Society in Journal of Physical Chemistry A, 2012, available online: http://pubs.acs.org/doi/abs/10.1021/jp3011519.
This work is supported by Grant-in-Aids (Grant No. 21350016) for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan, the Swiss National Science foundation through grant 200020_130579 and École Polytechnique Fédérale de Lausanne (EPFL).
journal title
Journal of Physical Chemistry A
volume
Volume 116
issue
Issue 16
start page
4057
end page
4068
date of issued
2012-04-26
publisher
American Chemical Society
issn
1089-5639
publisher doi
pubmed id
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) 2012 American Chemical Society
relation is version of URL
http://dx.doi.org/10.1021/jp3011519
department
Graduate School of Science