• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Molecular orbital studies of gas-phase interactions between complex molecules
【24h】

Molecular orbital studies of gas-phase interactions between complex molecules

机译：复杂分子间气相相互作用的分子轨道研究

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Describing, interactions among large molecules theoretically is a challenging task. As an example, we investigated gas-phase interactions between a linear nonionic oligomer and various model compounds (cofactors), which have been reported to associate experimentally, using PM3 semiempirical molecular orbital theory. As oligomer, we studied the hexamer of poly(ethylene oxide) (PEO), and as cofactors, we studied corilagin and related compounds containing phenolic groups (R-OH). These systems are of interest because they are models for PEO/cofactor flocculation systems, used in industrial applications. The PM3 delocalized molecular orbitals (DLMO) describe the bonding between (PEO)6 and cofactors, and some of them cover the complete complex. The DLMOs which cover the traditionally considered hydrogen bonds R-OH... 0 or R-CH center dot center dot center dot O show a distinct "pinch", a decrease of the electron density, between the H center dot center dot center dot O atoms. Calculations of Gibbs free energy, entropy, and enthalpy show that the PEO/cofactor complexes do not form at room temperature, because the loss of entropy exceeds the increase in enthalpy. The change in enthalpy is linearly related to the change in entropy for the different complexes. Even though bond lengths, bond angles, DLMOs, and electron densities for the PEO/cofactor complexes are consistent with the definition of hydrogen bonds, the number of intermolecular R-OH center dot center dot center dot O and R-CH center dot center dot center dot O bonds does not correlate with the enthalpy of association, indicating that the bonding mechanism for these systems is the sum of many small contributions of many delocalized orbitals.
机译：从理论上说，大分子之间的相互作用是一项艰巨的任务。例如，我们使用PM3半经验分子轨道理论研究了线性非离子低聚物与各种模型化合物（辅因子）之间的气相相互作用，据报道这些模型化合物在实验上具有相关性。作为低聚物，我们研究了聚环氧乙烷（PEO）的六聚体;作为辅因子，我们研究了可乐菌素和含有酚基（R-OH）的相关化合物。这些系统之所以令人感兴趣，是因为它们是用于工业应用中的PEO /辅因子絮凝系统的模型。 PM3离域分子轨道（DLMO）描述了（PEO）6与辅助因子之间的键合，其中一些覆盖了完整的复合物。覆盖传统上认为氢键R-OH ... 0或R-CH中心点中心点中心点O的DLMO在H中心点中心点中心点之间显示出明显的“捏”现象，即电子密度降低O原子。吉布斯自由能，熵和焓的计算表明，在室温下不会形成PEO /辅因子复合物，因为熵的损失超过了焓的增加。焓的变化与不同复合物的熵的变化线性相关。即使PEO /辅因子复合物的键长，键角，DLMO和电子密度与氢键的定义一致，分子间R-OH中心点中心点中心点O和R-CH中心点中心点的数目中心点O键与缔合焓不相关，表明这些系统的键合机制是许多离域轨道的许多小贡献的总和。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号