Quantum Chemical Benchmark Studies of the Electronic Properties of the Green Fluorescent Protein Chromophore. 1. Electronically Excited and Ionized States of the Anionic Chromophore in the Gas Phase
Quantum Chemical Benchmark Studies of the Electronic Properties of the Green Fluorescent Protein Chromophore. 1. Electronically Excited and Ionized States of the Anionic Chromophore in the Gas Phase
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DOI：
10.1021/ct900143j
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发表时间：
2009-07-01
影响因子：
5.5
通讯作者：
Krylov, Anna I.
中科院分区：
文献类型：
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作者：
Epifanovsky, Evgeny;Polyakov, Igor;Krylov, Anna I.
我们提出了绿色荧光蛋白发色团阴离子形式在气相中电子性质的量子化学计算结果。发现发色团的垂直剥离能在2.4 ~ 2.5 eV之间，低于强吸收态π π *的2.6 eV。最低三重态的垂直激发在1.9 eV左右，低于光剥离连续体。因此，最低亮单重态是嵌入在光剥离连续体中的共振态，而最低三重态是规则束缚态。根据我们对垂直分离能量的估计，我们将作用谱中的一个小特征归因于光分离跃迁。亮π π *态的基准结果表明，缩放的反自旋方法在距离实验最大值2.59 eV (479 nm) 0.1 eV （20 nm）的范围内产生垂直激发。我们还报道了用单双方法的运动方程耦合簇，多参考摄动理论修正方法MRMP2以及带距离分离泛函的时变密度泛函理论获得的垂直激发能估计。用漫射函数扩展基集，使π π *垂直激发能降低0.1 eV，同时显示出连续的“电离”态，其中嵌入了明亮的π π *跃迁。
We present the results of quantum chemical calculations of the electronic properties of the anionic form of the green fluorescent protein chromophore in the gas phase. The vertical detachment energy of the chromophore is found to be 2.4-2.5 eV, which is below the strongly absorbing pi pi* state at 2.6 eV. The vertical excitation of the lowest triplet state is around 1.9 eV, which is below the photodetachment continuum. Thus, the lowest bright singlet state is a resonance state embedded in the photodetachment continuum, whereas the lowest triplet state is a regular bound state. Based on our estimation of the vertical detachment energy, we attribute a minor feature in the action spectrum as due to the photodetachment transition. The benchmark results for the bright pi pi* state demonstrated that the scaled opposite-spin method yields vertical excitation within 0.1 eV (20 nm) from the experimental maximum at 2.59 eV (479 nm). We also report estimations of the vertical excitation energy obtained with the equation-of-motion coupled cluster with the singles and doubles method, a multireference perturbation theory corrected approach MRMP2 as well as the time-dependent density functional theory with range-separated functionals. Expanding the basis set with diffuse functions lowers the pi pi* vertical excitation energy by 0.1 eV at the same time revealing a continuum of "ionized" states, which embeds the bright pi pi* transition.