Observation of OH stretching vibrations of hydrogen-bonded molecular clusters

氢键分子簇OH伸缩振动的观察

• 批准号: 07454144
• 负责人: EBATA Takayuki
• 金额: $ 4.99万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454144/
• 关键词: hydrogen-bond; clusters; OH stretching vibration; supersonic jet; double resonance; phenol; vibrational relaxation; クラスター; 赤外スペクトル; ラマンスペクトル; hydrogen-bond; clusters; OH stretching vibration; supersonic jet; double resonance; phenol; vibrational relaxation; クラスター; 赤外スペクトル; ラマンスペクトル

The OH stretching vibrations of size-selected hydrogen-bonded clusters of aryl alcohols were observed in supersonic jets. Two spectroscopic methods were applied ; IR-UV double resonance and stimulated Raman-UV double resonance spectroscopies. The investigated hydrogen-bonded systems are phenol-(H_2O)_n, naphthol-(H_2O)_n, tropolone-(H_2O)_n, and also the clusters with other base molecules.In phenol-(H_2O)_n clusters (n=1-5), not only ^vOH of the phenol site but also of the water sites were observed. The cluster structures were investigated by comparing the observed spectra with the ones obtained by ab initio molecular orbital calulation. It was found that ring form hydrogen-bonded structure is most stable for the clusters with 2<less than or equal>n<less than or equal>4, and for larger size clusters, isomers different from the ringstructure seems to becomestable. The OH stretching spectra of naphthol-(H_2O)_n clusters are essentially the same with those of phenol-(H_2O)_n and a similar cluster structures are suggested. It was also found that the relaxation rate of the hydrogen bonded ^vOH are much larger than that of ^vOH free from the hydrogen bondThe decrease of ^vOH frequency by the hydrogen-bond formation versus the strength of basicity was investigated nad it was found the increase shows good correlation with the proton affinity of the base molecules.

在超音速喷气机中观察到了大小选择的氢键簇的OH拉伸振动。采用了两种光谱法。 IR-UV双共振和刺激Raman-UV双共振光谱。所研究的氢键系统是苯酚 - （H_2O）_n，Naphthol-（H_2O）_n，Tropolone-（H_2O）_n，以及其他基本分子的簇。通过比较观察到的光谱与从头算分子轨道小组获得的光谱来研究簇结构。已经发现，对于2 <小于或等于> n <少于或等于> 4的簇，环形的氢键结构最稳定，对于较大尺寸的簇，与环结构不同的异构体似乎是可变的。 Naptthol-（H_2O）_n簇的OH拉伸光谱与苯酚（H_2O）_n的簇基本相同，并建议使用类似的群集结构。还发现，氢键 ^voH的松弛速率比没有氢键的 ^voh的弛豫率大得多，氢键形成与碱性强度相比，研究了 ^voh频率的降低，发现增加的增加显示了与基础分子的质子亲和力的良好相关性。