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 AM_n (n = 1–4) clusters in supersonic jet by monitoring their fragments of H⁺AM_n–1 (n = 1–4) with vacuum ultraviolet single-photon soft ionization/IR-depletion technique. IR spectra of AM_n (n = 1–4) clusters were recorded in the CH and OH vibration bands in the range of 2700–3800 cm^–1. Spectra of AM_n (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 AM₃ conformers with the single ring on the C₁ side of acrylonitrile, such as C₁-AM-a, C₁-AM₂-a, and C₁-AM₃-a, are dominant in the gas phase, while the C₂-AM₄-a conformer with the H-bonded ring formed by the OH groups on the C₂ side 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.

中文翻译：

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气相星际分子簇[（C ₃ H ₃ N）（CH ₃ OH）_n，n = 1-4]的构象态势和红外光谱

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）是最常用的溶剂之一，它也在外层空间中发现。在这里，我们通过用真空紫外单脉冲监测H ⁺ AM _{n –1}（n = 1–4）的碎片，在超声速射流中获得了大小选定的AM _n（n = 1–4）团簇的红外光谱。光子软电离/红外耗尽技术。在CH和OH振动带的2700–3800 cm ^–1范围内记录了AM _n（n = 1-4）团簇的红外光谱。AM _n（n= 1-4）团簇在CH伸展区相似，但随着甲醇分子的增加，在OH伸展区出现明显变化。用B3LYP-D3（BJ）/ aug-cc-pVDZ方法预测的红外光谱与实验结果进行了比较。对于AM，AM ₂和AM ₃，具有与丙烯腈的[N1-C4（H6）]键合的甲醇环氢的结构比其他与H键合的结构更稳定。但是，对于AM ₄的最稳定结构，结果表明，丙烯腈与由四个甲醇分子的OH基形成的H键环结合。在C上带有单环的AM，AM ₂和AM ₃构象体丙烯腈的₁侧（例如C ₁ -AM-a，C ₁ -AM ₂ -a和C ₁ -AM ₃ -a）在气相中占优势，而C ₂ -AM ₄ -a构象与丙烯腈相同。在我们的实验条件（> 130 K）下，由丙烯腈C ₂侧的OH基形成的H键环比CM ₄ -Aa稳定。这些发现可能为星际分子和气相中其他生物分子的微溶剂化过程提供有价值的见解。