Conformation of Alkali Metal Ion−Benzo-12-Crown‑4 Complexes Investigated by UV Photodissociation and UV−UV Hole-Burning Spectroscopy

Journal of Physical Chemistry A 120 巻 32 号 6394-6401 頁 2016-07-26 発行
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タイトル ( eng )
Conformation of Alkali Metal Ion−Benzo-12-Crown‑4 Complexes Investigated by UV Photodissociation and UV−UV Hole-Burning Spectroscopy
作成者
Nakatsuma Maki
Kida Motoki
収録物名
Journal of Physical Chemistry A
120
32
開始ページ 6394
終了ページ 6401
抄録
We measure UV photodissociation (UVPD) spectra of benzo-12-crown-4 (B12C4) complexes with alkali metal ions, M+·B12C4 (M = Li, Na, K, Rb, and Cs), in the 36300−37600 cm−1 region. Thanks to the cooling of ions to ∼10 K, all the M+·B12C4 complexes show sharp vibronic bands in this region. For UV−UV hole-burning (HB) spectroscopy, we first check if our experimental system works well by observing UV−UV HB spectra of the K+ complex with benzo-18-crown-6 (B18C6), K+·B18C6. In the UV−UV HB spectra of the K+·B18C6 complex, gain signals are also observed; these are due to vibrationally hot K+·B18C6 complex produced by the UV excitation of cold K+·B18C6 complex. Then we apply UV−UV HB spectroscopy to the M+·B12C4 complexes, and only one conformer is found for each complex except for the Li+ complex, which has two conformers. The vibronic structure around the origin band of the UVPD spectra is quite similar for all the complexes, indicating close resemblance of the complex structure. The most stable structures calculated for the M+·B12C4 (M = Li, Na, K, Rb, and Cs) complexes also have a similar conformation among them, which coincides with the UVPD results. In these conformers the metal ions are too big to be included in the B12C4 cavity, even for the Li+ ion. In solution, it was reported that 12-crown-4 (12C4) shows the preference of Na+ ion among alkali metal ions. From the similarity of the structure for the M+·B12C4 complexes, it is suggested that the solvation of free metal ions, not of the M+·12C4 complexes, may lead to the selectivity of Na+ ion for 12C4 in solution.
内容記述
This work was partly supported by JSPS KAKENHI Grant Number 16H04098.
NDC分類
化学 [ 430 ]
言語
英語
資源タイプ 学術雑誌論文
出版者
American Chemical Society
発行日 2016-07-26
権利情報
Copyright (c) 2016 American Chemical Society
This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
出版タイプ Version of Record(出版社版。早期公開を含む)
アクセス権 オープンアクセス
収録物識別子
[ISSN] 1089-5639
[ISSN] 1520-5215
[DOI] 10.1021/acs.jpca.6b06626
[PMID] 27459367