Abstract

The investigation of solvated ion in nonaqueous or mixed solvent is a challenging task for experimental and theoretical chemistry. One of the promising approaches to elucidate the properties of solvated ion in mixed solvents is quantum mechanical charge field molecular dynamics (QMCF MD) simulation. In this study, we report the first application of QMCF MD simulation to investigate the structural and dynamical properties of solvated Ca²⁺ in 18.4% aqueous ammonia. Radial distribution function analysis showed that the average distances of Ca²⁺–N and Ca²⁺–O are 2.55 and 2.74 Å, respectively. The mean residence times for water and ammonia in the first solvation shell were calculated to be 2.8 and 2.74 ps, respectively. These values indicated a labile first solvation shell of Ca²⁺ in 18.4% aqueous ammonia. Meanwhile, angular distribution function analysis revealed the polyhedral structure of the first solvation shell. The average coordination numbers of 5.1 and 2.7 were obtained for water and ammonia, respectively, during the simulation. The presented simulation data provide detailed information about the properties of solvated Ca²⁺ in aqueous ammonia which will be beneficial to the investigation of the role of the ion in biological processes.

Graphic abstract

中文翻译：

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第一原理法研究稀氨水中第一溶剂化壳结构和溶剂化Ca 2+的动力学：QMCF MD模拟研究

摘要

研究非水或混合溶剂中的溶剂化离子对实验和理论化学而言是一项艰巨的任务。阐明混合溶剂中溶剂化离子性质的一种有前途的方法是量子机械电荷场分子动力学（QMCF MD）模拟。在这项研究中，我们报告了QMCF MD模拟在研究18.4％氨水中溶剂化Ca ²⁺的结构和动力学性质的首次应用。径向分布函数分析表明，Ca ²⁺ –N和Ca ²⁺的平均距离–O分别为2.55和2.74Å。计算得出第一溶剂化壳中水和氨的平均停留时间分别为2.8和2.74 ps。这些值表明Ca ²⁺在18.4％的氨水中不稳定的第一溶剂化壳。同时，角分布函数分析揭示了第一溶剂化壳的多面体结构。在模拟过程中，水和氨的平均配位数分别为5.1和2.7。所提供的模拟数据提供了有关氨水中Ca ²⁺溶剂化特性的详细信息，这将有利于研究离子在生物过程中的作用。

图形摘要