Shishido Ryunosuke, Kawai Yuki, Fujii Asuka
Department of Chemistry, Graduate School of Science, Tohoku University , Sendai 980-8578, Japan.
J Phys Chem A. 2014 Sep 4;118(35):7297-305. doi: 10.1021/jp4115157. Epub 2014 Mar 28.
The essence of the molecular recognition of the neurotransmitter acetylcholine has been attributed to the attractive interaction between a quaternary ammonium and aromatic rings. We employed protonated trimethylamine-(benzene)n clusters (n = 1-4) in the gas phase as a model to study the recognition mechanism of acetylcholine at the microscopic level. We applied size-selective infrared spectroscopy to the clusters and observed the NH and CH stretching vibrational regions. We also performed density functional theory calculations of stable structures, charge distributions, and infrared spectra of the clusters. It was shown that the methyl groups of protonated trimethylamine are solvated by benzene one at a time in the n > 1 clusters, and the validity of these clusters as a model system of the acetylcholine recognition was demonstrated. The nature of the interactions between a quaternary ammonium and aromatic rings is discussed on the basis of the observed infrared spectra and the theoretical calculations.
神经递质乙酰胆碱的分子识别本质归因于季铵盐与芳香环之间的吸引相互作用。我们采用气相中的质子化三甲胺 -（苯）n 簇（n = 1 - 4）作为模型，在微观层面研究乙酰胆碱的识别机制。我们对这些簇应用了尺寸选择性红外光谱，并观察了 NH 和 CH 伸缩振动区域。我们还对簇的稳定结构、电荷分布和红外光谱进行了密度泛函理论计算。结果表明，在 n > 1 的簇中，质子化三甲胺的甲基一次被一个苯溶剂化，证明了这些簇作为乙酰胆碱识别模型系统的有效性。基于观察到的红外光谱和理论计算，讨论了季铵盐与芳香环之间相互作用的本质。
