Theoretical Study of the Electronic Spectroscopy of Peptides. 1. The Peptidic Bond: Primary, Secondary, and Tertiary Amides
Theoretical Study of the Electronic Spectroscopy of Peptides. 1. The Peptidic Bond: Primary, Secondary, and Tertiary Amides
复制标题
肽电子光谱的理论研究。
DOI：
10.1021/ja961996
复制
发表时间：
1996
影响因子：
15
通讯作者：
M. Fülscher
中科院分区：
文献类型：
--
作者：
L. Serrano;M. Fülscher
本文讨论了一系列简单酰胺的吸收光谱，目的是研究蛋白质电子光谱的来源。用从头算量子化学方法、完全活性空间（CAS）SCF方法和多组态二阶微扰理论（CASPT 2）研究了激发态。我们计算了三个伯酰胺（甲酰胺，乙酰胺和丙酰胺），两个仲酰胺（N-甲基甲酰胺和N-甲基乙酰胺），和一个叔酰胺（N，N-二甲基甲酰胺）的垂直吸收光谱。计算包括大量的单重态和三重态价态和里德堡激发态。结果支持了光谱的基本结构：在气相中，一个强的π → π* 跃迁位于6.5和7.4 eV之间，第二个弱的π → π* 跃迁发生在9.6−10.5 eV。氮上的烷基取代对价态转变有重要影响：从伯原子到仲原子时能量下降，…
With the general aim to characterize the origin of electronic spectra of proteins, the present paper discusses the absorption spectra of a series of simple amides. Excited states were studied by means of ab initio quantum chemical methodsthe Complete Active Space (CAS) SCF method and multiconfigurational second order perturbation theory (CASPT2). We calculated the vertical absorption spectra of three primary amides (formamide, acetamide, and propanamide), two secondary amides (N-methylformamide and N-methylacetamide), and one tertiary amide (N,N-dimethylformamide). The calculations comprise a large number of singlet and triplet valence and Rydberg excited states. The results support a basic structure of the spectra: In gas phase one intense valence π → π* transition is placed between 6.5 and 7.4 eV and a second weak valence π → π* transition occurs at 9.6−10.5 eV. Alkyl substitutions on the nitrogen have a major effect on the valence transitions: The energy drops when going from primary to secondary and...