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ID 37647
本文ファイル
著者
Kusaka, Ryoji
Kokubu, Satoshi
NDC
化学
抄録(英)
Complexes of dibenzo-18-crown-6 (DB18C6, host) with water, ammonia, methanol, and acetylene (guest), formed in supersonic jets, have been characterized by using various spectroscopic methods: laser induced fluorescence (LIF), UV-UV hole-buning (UV-UV HB), and IR-UV double resonance (IR-UV DR) spectroscopy. Firstly, we reinvestigated the conformations of bare DB18C6 (species m1 and m2) and the structure of DB18C6-H2O (species a) [R. Kusaka, Y. Inokuchi, T. Ebata, Phys. Chem. Chem. Phys., 2008, 10, 6238] by measuring the IR-UV DR spectra in the region of the methylene CH stretching vibrations. From the IR-UV DR spectra, it was found that the IR spectral feature of the methylene CH stretch of DB18C6-H2O is clearly different from those of bare DB18C6 conformers, suggesting that DB18C6 changes its conformation when it forms the complex with a water molecule. With the aid of Monte Carlo simulation for extensive conformational search and density functional calculations (at B3LYP and M05-2X/6-31+G* levels), we reassigned the species m1 and m2 to the conformers belonging to C1 and C2 symmetry, respectively. On the other hand, we confirmed the DB18C6 part in the species a to be “boat” conformation, which is an unstable structure as the bare form. Secondly, we identified nine, one, and two species for DB18C6-ammonia, -methanol, and -acetylene complexes, respectively, by the combination of LIF and UV-UV HB spectroscopy. From the IR-UV DR spectra in the methylene CH stretching region, similar conformational change was identified in the DB18C6-ammonia complex, but not in the complexes with methanol or acetylene. The structures of all the complexes were determined by analyzing the electronic transition energies, exciton splitting, and IR-UV DR spectra in the region of the OH, NH, and CH stretching vibrations. In the DB18C6-ammonia complexes, a NH3 molecule is incorporated into the cavity of the boat conformation by forming bifurcated and bidentate hydrogen-bond (H-bond), similar to the case of the DB18C6-H2O complex. On the other hand, in the DB18C6-methanol and -acetylene complexes, methanol and acetylene molecules are simply attached to the C1 and C2 conformers, respectively, with their original conformations retained. From the difference of the DB18C6 conformation depending on the type of the guest molecules, it is concluded that DB18C6 distinguishes water and ammonia from methanol and acetylene when it forms complexes, depending on whether guest molecules have an ability to form bidentate H-bonding.
掲載誌名
Physical Chemistry Chemical Physics
13巻
15号
開始ページ
6827
終了ページ
6836
出版年月日
2011-03-14
出版者
Royal Society of Chemistry
ISSN
1463-9076
出版者DOI
言語
英語
NII資源タイプ
学術雑誌論文
広大資料タイプ
学術雑誌論文
DCMIタイプ
text
フォーマット
application/pdf
著者版フラグ
author
権利情報
Copyright (c) the Owner Societies 2011
関連情報URL(IsVersionOf)
http://dx.doi.org/10.1039/C0CP02523B
部局名
理学研究科