Electron-driven proton transfer enables nonradiative photodeactivation in microhydrated 2-aminoimidazole,Faraday Discussions

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Electron-driven proton transfer enables nonradiative photodeactivation in microhydrated 2-aminoimidazole
Faraday Discussions ( IF 3.3 ) Pub Date : 2018-05-16 , DOI: 10.1039/c8fd00086g
Mikołaj J. Janicki _{1,

2,

3,

4,

5} , Rafał Szabla _{5,

6,

7,

8,

9} , Jiří Šponer _{9,

10,

11} , Robert W. Góra _{1,

2,

3,

4,

5}

Affiliation

2-Aminoimidazole (2-AIM) was proposed as a plausible nucleotide activating group in a nonenzymatic copying and polymerization of short RNA sequences under prebiotically plausible conditions. One of the key selection factors controlling the lifespan and importance of organic molecules on early Earth was ultraviolet radiation from the young Sun. Therefore, to assess the suitability of 2-AIM for prebiotic chemistry, we performed non-adiabatic molecular dynamics simulations and static explorations of potential energy surfaces of the photoexcited 2-AIM–(H₂O)₅ model system by means of the algebraic diagrammatic construction method to the second order [ADC(2)]. Our quantum mechanical simulations demonstrate that ¹πσ* excited states play a crucial role in the radiationless deactivation of the UV-excited 2-AIM–(H₂O)₅ system. More precisely, electron-driven proton transfer (EDPT) along water wires is the only photorelaxation pathway leading to the formation of ¹πσ*/S₀ conical intersections. The availability of this mechanism and the lack of destructive photochemistry indicate that microhydrated 2-AIM is characterized by substantial photostability and resistance to prolonged UV irradiation.

中文翻译：

电子驱动的质子转移可在微水合2-氨基咪唑中实现非辐射光灭活

有人提出2-氨基咪唑（2-AIM）作为可能的核苷酸活化基团，用于在益生元合理的条件下短RNA序列的非酶复制和聚合中。控制早期地球有机分子的寿命和重要性的关键选择因素之一是年轻太阳发出的紫外线。因此，为了评估2-AIM对益生元化学的适用性，我们通过代数图解法对光激发的2-AIM–（H ₂ O）₅模型系统的势能面进行了非绝热分子动力学模拟和静态探索。二阶[ADC（2）]的构造方法。我们的量子力学模拟表明¹πσ*激发态在紫外线激发的2-AIM–（H ₂ O）₅系统的无辐射失活中起着至关重要的作用。更精确地，电子驱动的质子转移（EDPT）沿着水导线是唯一photorelaxation途径，导致形成¹ πσ* / S ₀圆锥交叉。该机制的可用性以及缺乏破坏性的光化学反应表明，微水合的2-AIM的特征在于基本的光稳定性和对长时间紫外线照射的抵抗力。

更新日期：2018-12-21

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