Kusaka Ryoji, Inokuchi Yoshiya, Ebata Takayuki
Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan.
Phys Chem Chem Phys. 2008 Nov 7;10(41):6238-44. doi: 10.1039/b807113f. Epub 2008 Sep 1.
The structure of dibenzo-18-crown-6-ether (DB18C6) and its hydrated clusters has been investigated in a supersonic jet. Two conformers of bare DB18C6 and six hydrated clusters (DB18C6-(H(2)O)(n)) were identified by laser-induced fluorescence, fluorescence-detected UV-UV hole-burning and IR-UV double-resonance spectroscopy. The IR-UV double resonance spectra were compared with the IR spectra obtained by quantum chemical calculations at the B3LYP/6-31+G* level. The two conformers of bare DB18C6 are assigned to "boat" and "chair I" forms, respectively, among which the boat form is dominant. All the six DB18C6-(H(2)O)(n) clusters with n = 1-4 have a boat conformation in the DB18C6 part. The water molecules form a variety of hydration networks in the boat-DB18C6 cavity. In DB18C6-(H(2)O)(1), a water molecule forms the bidentate hydrogen bond with the O atoms adjacent to the benzene rings. In this cluster, the water molecule is preferentially hydrogen bonded from the bottom of boat-DB18C6. In the larger clusters, the hydration networks are developed on the basis of the DB18C6-(H(2)O)(1) cluster.
在超声速射流中研究了二苯并 - 18 - 冠 - 6 - 醚（DB18C6）及其水合簇的结构。通过激光诱导荧光、荧光检测的紫外 - 紫外空穴烧蚀和红外 - 紫外双共振光谱鉴定了裸DB18C6的两种构象异构体和六个水合簇（DB18C6-(H₂O)ₙ）。将红外 - 紫外双共振光谱与在B3LYP/6 - 31 + G*水平通过量子化学计算获得的红外光谱进行了比较。裸DB18C6的两种构象异构体分别被指定为“船式”和“椅式I”形式，其中船式形式占主导。所有六个n = 1 - 4的DB18C6-(H₂O)ₙ簇在DB18C6部分具有船式构象。水分子在船式 - DB18C6腔内形成各种水合网络。在DB18C6-(H₂O)₁中，一个水分子与苯环相邻的O原子形成双齿氢键。在这个簇中，水分子优先从船式 - DB18C6的底部形成氢键。在较大的簇中，水合网络是在DB18C6-(H₂O)₁簇的基础上发展而来的。
