Vuković Lela, Burmeister Carl F, Král Petr, Groenhof Gerrit
†Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.
∥Department of Chemistry and Nanoscience Center, University of Jyväskylä, P.O. Box 35 FI-40014 Jyväskylä, Finland.
J Phys Chem Lett. 2013 Mar 21;4(6):1005-11. doi: 10.1021/jz400133u. Epub 2013 Mar 12.
We performed ab initio excited-state molecular dynamics simulations of a gas-phase photoexcited protonated Schiff base (C1-N2═C3-C4═C5-C6) to search for control mechanisms of its photoisomerization. The excited molecule twists by ∼90° around either the N2C3 bond or the C4C5 bond and relaxes to the ground electronic state through a conical intersection with either a trans or cis outcome. We show that a large initial distortion of several dihedral angles and a specific normal vibrational mode combining pyramidalization and double-bond twisting can lead to a preferential rotation of atoms around the C4C5 bond. We also show that selective pretwisting of several dihedral angles in the initial ground state thermal ensemble (by analogy to a protein pocket) can significantly increase the fraction of photoreactive (cis → trans) trajectories. We demonstrate that new ensembles with higher degrees of control over the photoisomerization reaction can be obtained by a computational directed evolution approach on the ensembles of molecules with the pretwisted geometries.
我们对气相光激发质子化席夫碱（C1-N2═C3-C4═C5-C6）进行了从头算激发态分子动力学模拟，以寻找其光异构化的控制机制。激发态分子围绕N2C3键或C4C5键扭转约90°，并通过与反式或顺式结果的锥形交叉弛豫到基态电子态。我们表明，几个二面角的大初始畸变以及结合锥形化和双键扭转的特定法向振动模式可导致原子围绕C4C5键优先旋转。我们还表明，在初始基态热系综中（类似于蛋白质口袋）对几个二面角进行选择性预扭转可显著增加光反应性（顺式→反式）轨迹的比例。我们证明，通过对具有预扭转几何结构的分子系综采用计算定向进化方法，可以获得对光异构化反应具有更高控制程度的新系综。
