Conformational Landscapes and Infrared Spectra of Gas -phase Interstellar Molecular Clusters [(C3H3N)(CH3OH), n=1-4]
Conformational Landscapes and Infrared Spectra of Gas -phase Interstellar Molecular Clusters [(C3H3N)(CH3OH), n=1-4]
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气相星际分子团簇的构象景观和红外光谱[(C3H3N)(CH3OH), n=1-4]
DOI：
10.1021/acs.jpca.9b11387
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发表时间：
2020
影响因子：
2.9
通讯作者：
Hu Yongjun
中科院分区：
文献类型：
--
作者：
Zhang Zhaoli;Nie Wuyi;Sun Fufei;Zhang Yu;Xie Min;Hu Yongjun
丙烯腈（A）是重要的星际分子之一，被认为与生命起源密切相关。甲醇（M）是常用的溶剂之一，也存在于外层空间。本文采用真空紫外单光子软电离/红外耗尽技术，通过监测H+AMn-1（n = 1 - 4）的碎片，获得了超声射流中AMn（n = 1 - 4）团簇的红外光谱。AMn（n= 1-4）簇合物的红外光谱在2700-3800 cm-1的CH和OH振动带记录。AMn（n= 1-4）团簇的光谱在CH伸缩区相似，而OH伸缩区随甲醇分子数的增加有明显的变化。用B3 LYP-D3（BJ）/aug-cc-pVDZ方法预测了红外光谱，并与实验结果进行了比较。对于AM、AM 2和AM 3，甲醇环与丙烯腈的[N1-C4（H6）]形成氢键的结构比其它氢键结构更稳定。然而，对于AM4的最稳定的结构，结果表明，丙烯腈结合到由四个甲醇分子的OH基团形成的H-键合环。在气相中，C1-AM-a、C1-AM 2-a和C1-AM3-a等单体在丙烯腈的C1侧形成单环，而C2-AM4-a在丙烯腈的C2侧形成氢键环，在我们的实验条件下（>130 K）比CM 4-A-a更稳定。这些发现可能为星际分子和其他生物分子在气相中的微溶剂化过程提供有价值的见解。
Acrylonitrile (A) is one of the important interstellar molecules, which is considered closely related to the origin of life. And methanol (M) is one of the commonly used solvents, which is also found in outer space. Herein, we obtained the infrared (IR) spectra of size-selected AMn(n= 1–4) clusters in supersonic jet by monitoring their fragments of H+AMn–1(n= 1–4) with vacuum ultraviolet single-photon soft ionization/IR-depletion technique. IR spectra of AMn(n= 1–4) clusters were recorded in the CH and OH vibration bands in the range of 2700–3800 cm–1. Spectra of AMn(n= 1–4) clusters are similar in the CH stretching regions, while those show significant variations in the OH stretching regions with the increase of methanol molecules. Calculated IR spectra, which were predicted with the B3LYP-D3(BJ)/aug-cc-pVDZ method, were employed to compare with the experimental results. For AM, AM2, and AM3, the structures with the methanol cyclic hydrogen bonded with [N1–C4(H6)] of acrylonitrile are more stable than the other H-bonded structures. For the most stable structures of AM4, however, the results show that the acrylonitrile is binding to a H-bonded ring formed by OH groups of four methanol molecules. The AM, AM2, and AM3conformers with the single ring on theC1side of acrylonitrile, such asC1-AM-a,C1-AM2-a, andC1-AM3-a, are dominant in the gas phase, while theC2-AM4-a conformer with the H-bonded ring formed by the OH groups on theC2side of acrylonitrile is more stable than that of CM4-A-a in our experimental conditions (>130 K). These findings may provide valuable insight into the microsolvation process of the interstellar molecules and other biomolecules in gas phase.