Microhydration Effects on the Encapsulation of Potassium Ion by Dibenzo-18-Crown-6
Journal of the American Chemical Society 136 巻 5 号
1815-1824 頁
2014-02-05 発行
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| ファイル情報(添付) | |
| タイトル ( eng ) |
Microhydration Effects on the Encapsulation of Potassium Ion by Dibenzo-18-Crown-6
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| 作成者 |
Rizzo Thomas R.
Boyarkin Oleg V.
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| 収録物名 |
Journal of the American Chemical Society
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| 巻 | 136 |
| 号 | 5 |
| 開始ページ | 1815 |
| 終了ページ | 1824 |
| 抄録 |
We have measured electronic and conformer-specific vibrational spectra of hydrated dibenzo-18-crown-6 (DB18C6) complexes with potassium ion, K+・DB18C6・(H2O)n (n = 1－5), in a cold, 22-pole ion trap. We also present for comparison spectra of Rb+・DB18C6・(H2O)3 and Cs+・DB18C6・(H2O)3 complexes. We determine the number and the structure of conformers by analyzing the spectra with the aid of quantum chemical calculations. The K+・DB18C6・(H2O)1 complex has only one conformer under the conditions of our experiment. For K+・DB18C6・H2O)n with n = 2 and 3, there are at least two conformers even under the cold conditions, whereas Rb+・DB18C6・(H2O)3 and Cs+・DB18C6・(H2O)3 each exhibit only one isomer. The difference can be explained by the optimum matching in size between the K+ ion and the crown cavity; since the K+ ion can be deeply encapsulated by DB18C6 and the interaction between the K+ ion and the H2O molecules becomes weak, different kinds of hydration geometries can occur for the K+・DB18C6 complex, giving multiple conformations in the experiment. For K+・DB18C6・(H2O)n (n = 4 and 5) complexes, only a single isomer is found. This is attributed to a cooperative effect of the H2O molecules on the hydration of K+・DB18C6; the H2O molecules form a ring, which is bound on top of the K+・DB18C6 complex. According to the stable structure determined in this study, the K+ ion in the K+・DB18C6・(H2O)n complexes tends to be pulled largely out from the crown cavity by the H2O molecules with increasing n. Multiple conformations observed for the K+ complexes will have an advantage for the effective capture of the K+ ion over the other alkali metal ions by DB18C6 because of entropic effects on the formation of hydrated complexes.
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| 著者キーワード |
alkali metal ions
18-crown-6
encapsulation
water
crown ether
infrared
ion trap
electrospray
solvent effect
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| 内容記述 |
This is a preprint of an article published by American Chemical Society in Journal of the American Chemical Society, 2014, available online: http://pubs.acs.org/doi/abs/10.1021/ja4086066.
This work is partly supported by JSPS KAKENHI Grant Number 21350016, and the Swiss National Science foundation through grant 200020_130579 and École Polytechnique Fédérale de Lausanne (EPFL).
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| NDC分類 |
化学 [ 430 ]
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| 言語 |
英語
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| 資源タイプ | 学術雑誌論文 |
| 出版者 |
American Chemical Society
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| 発行日 | 2014-02-05 |
| 権利情報 |
Copyright (c) 2014 American Chemical Society
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| 出版タイプ | Author’s Original（十分な品質であるとして、著者から正式な査読に提出される版） |
| アクセス権 | オープンアクセス |
| 収録物識別子 |
[ISSN] 0002-7863
[DOI] 10.1021/ja4086066
[PMID] 24422522
[DOI] http://dx.doi.org/10.1021/ja4086066
～の異版である
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