Hydration effect on positron binding ability for proline: Positron attachment induces proton-transfer to form zwitterionic structure
Hydration effect on positron binding ability for proline: Positron attachment induces proton-transfer to form zwitterionic structure
复制标题
水合对脯氨酸正电子结合能力的影响：正电子附着诱导质子转移形成两性离子结构
DOI：
10.1021/acs.jpca.8b11653
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发表时间：
2019
期刊：
影响因子：
2.9
通讯作者：
and M. Tachikawa
中科院分区：
文献类型：
--
作者：
K. Suzuki;Y. Sugiura;T. Takayanagi;Y. Kita;and M. Tachikawa
用多组分分子轨道（MC_MO）方法研究了脯氨酸及其水合团簇的正电子结合能力。利用全局反应路线作图程序对中性脯氨酸·（H2O）n（n= 0-2）团簇的低位平衡结构进行了系统的研究.然后计算了平衡结构的正电子结合能。我们发现，两性离子的形式通常显示高的正电子结合能，由于其高极性的性质。我们还发现，非两性离子的形式可以表现出高的正电子结合能，如果水的加入显着增加的总电偶极矩。这些结果表明，最稳定的正电子束缚脯氨酸·（H2O）n（n= 1和2）结构比最稳定的中性结构更稳定，这意味着如果正电子-电子湮灭寿命相对于核运动的时间尺度足够长，正电子与中性水合脯氨酸团簇的连接可以引起结构变化.我们还研究了正电子结合对质子转移反应的能量分布的影响，从非两性离子形式的两性离子形式。
The positron binding abilities of proline and its hydrated clusters were theoretically studied using multicomponent molecular orbital (MC_MO) calculations. Low-lying equilibrium structures of the neutral proline·(H2O)n(n= 0–2) clusters were systematically explored with the aid of global reaction route mapping code. The positron binding energies were then calculated for the equilibrium structures. We found that the zwitterionic forms generally displayed high positron binding energies owing to their highly polar nature. We also found that nonzwitterionic forms can exhibit high positron binding energies if the addition of water significantly increases the total electric dipole moment. These results demonstrate that the most stable positron-bound proline·(H2O)n(n= 1 and 2) structures are more stable than the most stable neutral structures, which implies that the attachment of a positron to a neutral hydrated proline cluster can induce structural changes if the positron–electron annihilation lifetime is sufficiently long relative to the time scale of nuclear motion. We also examined the influence of positron binding on the energy profiles of the proton transfer reactions from the nonzwitterionic form to the zwitterionic form.