Ranga Santosh, Mukherjee Madhubani, Dutta Achintya Kumar
Department of Chemistry, Indian Institute of Technology (IIT), Bombay, Powai, Maharastra, 400076, India.
Chemphyschem. 2020 May 18;21(10):1019-1027. doi: 10.1002/cphc.202000133. Epub 2020 Apr 14.
We have investigated the effect of base pairing on the electron attachment to nucleobases in bulk water, taking the guanine-cytosine (GC) base pair as a test case. The presence of the complementary base reinforces the stabilization effect provided by water and preferentially stabilizes the anion by hydrogen bonding. The electron attachment in bulk-solvated GC happens through a doorway mechanism, where the initial electron attached state is water bound, and it subsequently gets converted to a GC bound state. The additional electron in the final GC bound state is localized on the cytosine, similar to that in the gas phase. The transfer of the electron from the initial water-bound state to the final GC bound state happens due to the mixing of electronic and nuclear degrees of freedom and takes place at a picosecond time scale.
我们以鸟嘌呤 - 胞嘧啶（GC）碱基对作为测试案例，研究了碱基配对对本体水中核碱基电子附着的影响。互补碱基的存在增强了水所提供的稳定作用，并通过氢键优先稳定阴离子。本体溶剂化的GC中的电子附着通过一种门道机制发生，其中初始电子附着态是与水结合的，随后它会转变为与GC结合的状态。最终与GC结合状态下的额外电子定域在胞嘧啶上，这与气相中的情况类似。电子从初始与水结合的状态转移到最终与GC结合的状态是由于电子和核自由度的混合，且发生在皮秒时间尺度上。
