On the Simulation of Two-dimensional Electronic Spectroscopy of Indole-containing Peptides
On the Simulation of Two-dimensional Electronic Spectroscopy of Indole-containing Peptides
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DOI：
10.1111/php.12770
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发表时间：
2017-11-01
影响因子：
3.3
通讯作者：
Nenov, Artur
中科院分区：
文献类型：
--
作者：
Giussani, Angelo;Marcheselli, Jacopo;Nenov, Artur
对用于计算吲哚电子结构的低成本多组态CASSCF/CASPT2格式进行了基准研究。这有助于模拟近紫外(UV)泵浦可见(VIS)探针(即双色)同聚体和杂聚体的二维电子光谱(2DES)，以及处理来自分子动力学模拟的多个快照。在10~25k cm(-1)的宽光谱范围内，可识别吲哚的指纹激发态吸收特征。18-24k cm(-1)的光谱窗口不吸收单体和非相互作用的聚集体，非常适合在堆积聚集体中嵌入电荷转移特征。小肽Trp-Cage含有色氨酸和酪氨酸氨基酸，分别以吲哚和苯酚为侧链，用于证明这一概念。在生色团间距为5埃的光谱窗口中发现了清晰的电荷转移特征，这使得近紫外泵浦VIS探针2DES是一种适合于解析紧密堆积聚集体的技术。我们证明了利用超短脉冲的2DES有可能分辨光谱分辨电子态的性质，并且激发态吸收信号的线形可以与相关态的极性相关联。
A benchmark study of low-cost multiconfigurational CASSCF/CASPT2 schemes for computing the electronic structure of indole is presented. This facilitates the simulation of near-ultraviolet (UV) pump visible (VIS) probe (i.e. two-color) two-dimensional electronic spectra (2DES) of homo- and hetero-aggregates as well as for processing of multiple snapshots from molecular dynamics simulations. Fingerprint excited-state absorption signatures of indole are identified in a broad spectral window between 10 and 25 k cm(-1). The 18-24 k cm(-1) spectral window which has no absorption of the monomer and noninteracting aggregates is ideally suited to embed charge-transfer signatures in stacked aggregates. The small peptide Trp-cage, containing a tryptophan and a tyrosine amino acids, having indole and phenol as side chains, respectively, serves to prove the concept. Clear charge-transfer signatures are found in the proposed spectral window for an interchromophore distance of 5 angstrom making near-UV pump VIS probe 2DES a suitable technique for resolving closely packed aggregates. We demonstrate that 2DES utilizing ultra-short pulses has the potential to resolve the nature of the spectroscopically resolved electronic states and that the line shapes of the excited-state absorption signals can be correlated to the polarity of the relevant states.