Effect of DNA Environment on Electronically Excited States of Methylene Blue Evaluated by a Three-Layered QM/QM/MM ONIOM Scheme,Journal of Chemical Theory and Computation

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Effect of DNA Environment on Electronically Excited States of Methylene Blue Evaluated by a Three-Layered QM/QM/MM ONIOM Scheme
Journal of Chemical Theory and Computation ( IF 5.7 ) Pub Date : 2018-06-15 00:00:00 , DOI: 10.1021/acs.jctc.8b00185
Juan J. Nogueira ₁ , Sven Roßbach ₂ , Christian Ochsenfeld ₂ , Leticia González ₁

Affiliation

Interactions between chromophores and biological environments may alter the electronic properties of the chromophores. A three-layered QM/QM/MM ONIOM scheme with electrostatic embedding is implemented to investigate the influence of an additional QM layer on excited-state calculations with respect to a standard QM/MM description. The implemented ONIOM scheme is employed to compute the electronic excitations of the photosensitizer methylene blue interacting with a solvated DNA double strand. It is shown that the additional quantum mechanical description of several nucleobases in the vertical energy calculations induces energy shifts in the excited states of methylene blue, compared to the energies of a traditional QM/MM scheme, where the solvated double strand is described fully classically. The energy shifts present an electrostatic component, caused by a charge redistribution of the environment, and an electronic-coupling component, originated by the mixing between the electronic bright state of methylene blue and a charge-transfer state between methylene blue and guanine. In addition, hydrogen bonding and stacking interactions are stronger when the environment is described quantum mechanically during the geometry optimizations than when it is fully described by molecular mechanics. These larger intermolecular interactions produce further energy shifts in the excitation energies of the photosensitizer.

中文翻译：

三层QM / QM / MM ONIOM方案评估DNA环境对亚甲基蓝电激发态的影响

生色团与生物环境之间的相互作用可能会改变生色团的电子特性。实施了带有静电嵌入的三层QM / QM / MM ONIOM方案，以针对标准QM / MM描述研究附加QM层对激发态计算的影响。实施的ONIOM方案用于计算与溶剂化DNA双链相互作用的光敏剂亚甲基蓝的电子激发。结果表明，与传统的QM / MM方案的能量（其中溶剂化的双链被完全经典地描述）相比，垂直能量计算中几个核碱基的额外量子力学描述在亚甲基蓝的激发态中引起了能量转移。能量转移呈现出静电成分，由环境电荷的重新分布和电子耦合成分引起的，这是由亚甲基蓝的电子亮态与亚甲基蓝和鸟嘌呤之间的电荷转移态之间的混合引起的。另外，当在几何优化过程中用量子力学描述环境时，氢键和堆积相互作用要比用分子力学完全描述时强。这些较大的分子间相互作用在光敏剂的激发能中产生进一步的能量转移。当在几何优化过程中以机械方式描述量子环境时，氢键和堆叠相互作用比通过分子力学全面描述时更强。这些较大的分子间相互作用在光敏剂的激发能中产生进一步的能量转移。当在几何优化过程中以机械方式描述量子环境时，氢键和堆叠相互作用比通过分子力学全面描述时更强。这些较大的分子间相互作用在光敏剂的激发能中产生进一步的能量转移。

更新日期：2018-06-15

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