在星际媒介中合成H2NCH2CN分子的理论研究

摘要

Amino acids are important biological compounds that played an essential role in the formation of peptides, the backbone of protein, in the prebiotic chemistry of the early Earth for the origin of life. To probe for a possible new origin of amino acids, density functional theory at the B3LYP/6-311++G(d, p) level has been carried out for important reactions between methaneimine, CH2NH, and the two isomers HNC/HCN via Strecker synthesis route,leading to the formation of aminoacetonitrile, H2NCH2CN, a precursor of glycine, both in the gas phase and on a model icy grain surface in the interstellar medium (ISM). This study shows the very feasible formation of H2NCH2CN among the CH2NH, HCN, HNC, and H2O molecules that are widespread in the interstellar dense molecular cloud before the Earth began and on the model icy grain surface in the ISM via Strecker synthesis route. This article discusses that H2NCH2CN might be prevalent throughout the Universe in the interstellar dense molecular cloud and then implies the importance of H2NCH2CN in the origin of amino acids and in the origin of life with respect to the "Primordial Soup" theory on the early Earth.%在早期地球原始化学生命起源过程中,氨基酸是重要的必需的生物化合物,生成肽和蛋白.为了探究一个可能的新的氨基酸起源,采用密度泛函理论(B3LYP)在6-311++G(d,p)基组水平上研究了在星际媒介条件下在气相中和在模拟的冰颗粒表面上的化学反应:CH2NH分子和两个异构体分子HNC/HCN通过Strecker合成生成H2NCH2CN(氨基乙氰,一个重要的苷氨基酸前置分子).在研究体系中,CH2NH、HCN、HNC和H2O分子存在于星际密集分子云中,且早于地球广泛存在.研究证明,这些分子之间在星际媒介条件下和在冰颗粒表面上通过Strecker合成路线很容易生成H2NCH2CN.所以,H2NCH2CN分子在宇宙的星际密集分子云中是广泛存在的.还讨论了H2NCH2CN分子在新的氨基酸起源中所起的作用,以及在通过"原始汤"生命起源理论解析早期地球生命起源中可能所起的作用.