Cooperativity of hydrogen-bonded networks in 7-azaindole(CH3OH)n (n=2,3) clusters evidenced by IR-UV ion-dip spectroscopy and natural bond orbital analysis.
Cooperativity of hydrogen-bonded networks in 7-azaindole(CH3OH)n (n=2,3) clusters evidenced by IR-UV ion-dip spectroscopy and natural bond orbital analysis.
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DOI：
10.1063/1.2961031
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发表时间：
2008-08
期刊：
影响因子：
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通讯作者：
Kenji Sakota;Yutaka Kageura;H. Sekiya
中科院分区：
文献类型：
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作者：
Kenji Sakota;Yutaka Kageura;H. Sekiya
在氢键NH和OH拉伸区测量了7-氮杂吲哚（7AI）（CH(3)OH）(n) （n=1-3）簇的IR-UV离子浸光度，研究了7AI(CH(3)OH)(n) （n=1-3）在S(0)态的稳定结构和氢键网络中氢键相互作用的协同性。红外紫外光谱与量子化学计算得到的红外光谱对比表明，7AI(CH(3)OH)(n) （n=1-3）具有环状氢键结构，其中NH基团和杂芳香n原子分别作为质子给体和质子受体。7AI(CH(3)OH)(2)的氢键伸展基与（CH(3)OH）(2)的相应基明显红移286 cm(-1)，这是氢键相互作用中协同性的实验表现。同样，7AI(CH(3)OH)(3)的两个局部OH基元也表现出较大的红移。7AI(CH(3)OH)(n) （n=2,3）的协同性在自然键轨道（NBO）分析中用质子受体的孤对轨道和质子给体的反键轨道之间的电子离域相互作用成功地解释了。
IR-UV ion-dip spectra of the 7-azaindole (7AI)(CH(3)OH)(n) (n=1-3) clusters have been measured in the hydrogen-bonded NH and OH stretching regions to investigate the stable structures of 7AI(CH(3)OH)(n) (n=1-3) in the S(0) state and the cooperativity of the H-bonding interactions in the H-bonded networks. The comparison of the IR-UV ion-dip spectra with IR spectra obtained by quantum chemistry calculations shows that 7AI(CH(3)OH)(n) (n=1-3) have cyclic H-bonded structures, where the NH group and the heteroaromatic N atom of 7AI act as the proton donor and proton acceptor, respectively. The H-bonded OH stretch fundamental of 7AI(CH(3)OH)(2) is remarkably redshifted from the corresponding fundamental of (CH(3)OH)(2) by 286 cm(-1), which is an experimental manifestation of the cooperativity in H-bonding interaction. Similarly, two localized OH fundamentals of 7AI(CH(3)OH)(3) also exhibit large redshifts. The cooperativity of 7AI(CH(3)OH)(n) (n=2,3) is successfully explained by the donor-acceptor electron delocalization interactions between the lone-pair orbital in the proton acceptor and the antibonding orbital in the proton donor in natural bond orbital (NBO) analyses.