Laser Spectroscopic Study on (Dibenzo-24-Crown-8-Ether)-Water and -Methanol Complexes in Supersonic Jets
Laser Spectroscopic Study on (Dibenzo-24-Crown-8-Ether)-Water and -Methanol Complexes in Supersonic Jets
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超音速射流中 (二苯并-24-冠-8-醚)-水和-甲醇配合物的激光光谱研究
DOI：
10.1039/b924822f
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
and T. Ebata
中科院分区：
文献类型：
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作者：
S. Kokubu;R. Kusaka;Y. Inokuchi;T. Haino;and T. Ebata
通过激光诱导荧光 (LIF)、紫外-紫外烧孔 (UV-UV HB) 和红外-紫外双共振 (IR-UV DR) 光谱研究了喷射冷却的二苯并-24-冠-8-醚 (DB24C8) 的构象和与客体分子的复合物形成。将结果与二苯并18冠6醚（DB18C6）的结果进行比较，并在B3LYP/6-31+G*水平上通过密度泛函理论（DFT）计算进行分析。在喷射冷却条件下，DB24C8 鉴定出 5 个构象异构体，并且主要异构体的结构被确定为船形，类似于 DB18C6 的情况。研究两种分子（水和甲醇）作为封装实验的客体物种。 DB24C8几乎不封装水分子，这与有效捕获水分子的DB18C6的情况不同。然而，DB24C8 腔中可能会捕获较大的（水）n 团簇。 DB24C8和DB24C8与水分子形成复合物的不同特征归因于DB24C8比DB18C6具有更大的空腔尺寸。对于甲醇，通过IR-UV DR 光谱鉴定出两种DB18C6–(methanol)1 异构体；一种是“OH⋯π”氢键异构体，是带有一个OH基团的甲醇的特征，另一种是“OH⋯O”氢键异构体。这些结果表明，与醚环的氧原子形成的多个氢键可能在DB24C8或DB18C6与水的络合物中起重要作用。
The conformation and complex formation with guest molecules have been investigated for jet-cooled dibenzo-24-crown-8-ether (DB24C8) by laser induced fluorescence (LIF), UV-UV hole-burning (UV-UV HB), and IR-UV double-resonance (IR-UV DR) spectroscopy. The results are compared with the results of dibenzo-18-crown-6-ether (DB18C6) and analyzed by density functional theory (DFT) calculations at the B3LYP/6-31+G* level. Five conformers are identified for DB24C8 under jet-cooled conditions, and the structure of the major isomer is determined to be a boat form, similar to the case of DB18C6. Two molecules (water and methanol) are investigated as the guest species for the encapsulation experiment. DB24C8 hardly encapsulates a water molecule, different from the case of DB18C6 in which a water molecule is efficiently captured. However, it is likely that larger (water)n clusters can be captured in the DB24C8 cavity. The different feature in the complex formation between DB24C8 and DB24C8 with the water molecules are attributed to a larger cavity size of DB24C8 than that of DB18C6. For methanol, two kinds of DB18C6–(methanol)1 isomers are identified by IR-UV DR spectroscopy; one is the “OH⋯π” H-bonded isomer, characteristic of methanol with one OH group, and the other is the “OH⋯O” H-bonded ones. These results indicate the multiple H-bond formation to the oxygen atoms of the ether ring may play an important role in the complexes of DB24C8 or DB18C6 with water.