Solvation Effect on the NH Stretching Vibrations of Solvated Aminopyrazine, 2-Aminopyridine, and3-Aminopyridine Clusters
Solvation Effect on the NH Stretching Vibrations of Solvated Aminopyrazine, 2-Aminopyridine, and3-Aminopyridine Clusters
复制标题
溶剂化氨基吡嗪、2-氨基吡啶和3-氨基吡啶簇的NH伸缩振动的溶剂化效应
DOI：
10.1021/jp306609f
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Y. Nibu
中科院分区：
文献类型：
--
作者：
Y. Yamada;H. Ohba;Y. Noboru;S. Daicho;Y. Nibu
用红外-紫外双共振光谱法测量了氨基吡嗪、2-氨基吡啶和3-氨基吡啶的水化和甲醇溶剂化产物在超声速射流中的振动光谱。将氨基吡嗪的IR光谱与2-氨基吡啶和3-氨基吡啶簇的IR光谱进行比较，我们确定氨基吡嗪的溶剂化结构是与水合2-氨基吡啶簇类似的环状结构[Wu等人，Phys.Chem.Chem.Phys.2004，6，515]。在一水合氨基吡嗪簇合物中，OH和NH伸缩局域模组成的一个简正模给出了非常弱的红外强度，这归因于OH和NH伸缩局域模之间的偶极矩变化的抵消.溶剂化的3-氨基吡啶簇合物在吡啶氮原子和OH基团之间形成氢键，但氨基间接地受到影响，引起NH 2伸缩线轻微蓝移。这一现象是由诱导效应解释的，其中在溶剂化时从氨基基团吸电子导致氨基基团的“类醌”结构。
The vibrational spectra of the hydrated and methanol-solvated aminopyrazine, 2-aminopyridine and 3-aminopyridine in supersonic jets have been measured in terms of IR-UV double-resonance spectroscopy. Comparing the IR spectrum of aminopyrazine with those of 2-aminopyridine and 3-aminopyridine clusters, we determine the solvation structure of aminopyrazine to be a similar cyclic structure as hydrated 2-aminopyridine clusters [Wu, et al.,Phys. Chem. Chem. Phys.2004, 6, 515]. In the case of monohydrated aminopyrazine cluster, one of the normal modes composed of the hydrogen-bonded OH and NH stretching local modes gives the anomalously weak IR intensity, which is ascribed to the cancellation of the dipole moment change between the OH and NH stretching local modes. The solvated 3-aminopyridine clusters forms the hydrogen-bond between the pyridyl nitrogen atom and the OH group, but the amino group is indirectly affected to induce slight blue shift of the NH2stretches. This phenomenon is explained by inductive effect where the electron withdrawing from the amino group upon the solvation results in a “quinoid-like” structure of the amino group.