A theoretical study on the size-dependence of ground-state proton transfer in phenol-ammonia clusters
A theoretical study on the size-dependence of ground-state proton transfer in phenol-ammonia clusters
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酚-氨团簇中基态质子转移尺寸依赖性的理论研究
DOI：
10.1039/c7cp05247b
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发表时间：
2018
影响因子：
3.3
通讯作者：
Fujii Masaaki
中科院分区：
文献类型：
--
作者：
Shimizu Toshihiko;Hashimoto Kenro;Hada Masahiko;Miyazaki Mitsuhiko;Fujii Masaaki
使用密度泛函理论 (DFT) 研究了苯酚–(氨)n (PhOH–(NH3)n) (n = 0–10) 团簇中红外区域的几何形状和红外 (IR) 光谱，以研究促进基态质子转移 (GSPT) 所需的溶剂分子的临界数量。对于 n ≤ 8 簇，最稳定的异构体是非质子转移（非 PT）结构，并且在 1.5 kcal mol−1 范围内发现的所有异构体也都是非 PT 结构。对于n=9，最稳定的异构体也是非PT结构；然而，第二个稳定异构体是PT结构，其相对能量在总体实验标准（0.7 kcal mol−1）内。当 n = 10 时，PT 结构是最稳定的结构。因此，我们可以估计 GSPT 的临界尺寸为 n = 9。这些计算出的红外光谱与我们之前的中红外光谱实验结果非常一致，这一事实证实了这一点。结果表明，骨骼振动区域ν9a和ν12带的特征变化提供了GSPT反应发生的明确信息。还发现π环和溶剂部分之间的最短距离是PT反应的良好指标。
Geometries and infrared (IR) spectra in the mid-IR region of phenol–(ammonia)n (PhOH–(NH3)n) (n = 0–10) clusters have been studied using density functional theory (DFT) to investigate the critical number of solvent molecules necessary to promote ground-state proton transfer (GSPT). For n ≤ 8 clusters, the most stable isomer is a non-proton-transferred (non-PT) structure, and all isomers found within 1.5 kcal mol−1 from it are also non-PT structures. For n = 9, the most stable isomer is also a non-PT structure; however, the second stable isomer is a PT structure, whose relative energy is within the experimental criterion of population (0.7 kcal mol−1). For n = 10, the PT structure is the most stable one. We can therefore estimate that the critical size of GSPT is n = 9. This is confirmed by the fact that these calculated IR spectra are in good accordance with our previous experimental results of mid-IR spectra. It is demonstrated that characteristic changes of the ν9a and ν12 bands in the skeletal vibrational region provide clear information that the GSPT reaction has occurred. It was also found that the shortest distance between the π-ring and the solvent moiety is a good indicator of the PT reaction.