• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The Journal of Chemical Physics >Inelastic neutron scattering of large molecular systems: The case of the original benzylic amide [2]catenane
【24h】

Inelastic neutron scattering of large molecular systems: The case of the original benzylic amide [2]catenane

机译：大分子系统的非弹性中子散射：原始苄基酰胺[2]环烷的情况

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

The inelastic neutron scattering (INS) spectrum of the original benzylic amide [2]catenane is recorded and simulated by a semiempirical quantum chemical procedure coupled with the most comprehensive approach available to date, the CLIMAX. program. The successful simulation of the spectrum indicates that the modified neglect of differential overlap (MNDO) model can reproduce the intramolecular vibrations of a molecular system as large as a catenane (136 atoms). Because of the computational costs involved and some numerical instabilities, a less expensive approach is attempted which involves the molecular mechanics-based calculation of the INS response in terms of the most basic formulation for the scattering activity. The encouraging results obtained validate the less computationally intensive procedure and allow its extension to the calculation of the INS spectrum for a second, theoretical, co-conformer, which, although structurally and energetically reasonable, is not, in fact, found in the solid state. The second structure was produced by a Monte Carlo simulated annealing method run in the conformational space (a procedure that would have been prohibitively expensive at the semiempirical level) and is characterized by a higher degree of intramolecular hydrogen bonding than the x-ray structure. The two alternative structures yield different simulated spectra, only one of which, the authentic one, is compatible with the experimental data. Comparison of the two simulated and experimental spectra affords the identification of an inelastic neutron scattering spectral signature of the correct hydrogen bending motif in the region slightly above 700 cm(-1). The study illustrates that combinations of simulated INS data and experimental results can be successfully used to discriminate between different proposed structures or possible hydrogen bonding motifs in large functional molecular systems, (C) 1998 American Institute of Physics. [S0021-9606(98)30948-4]. [References: 30]
机译：原始的苄基酰胺[2]链烷的非弹性中子散射（INS）光谱是通过半经验量子化学方法与迄今为止最全面的方法CLIMAX进行记录和模拟的。程序。光谱的成功模拟表明，修正的差分重叠忽略（MNDO）模型可以重现与链烷烃（136个原子）一样大的分子系统的分子内振动。由于所涉及的计算成本和某些数值不稳定性，尝试了一种较便宜的方法，该方法涉及基于分子力学的INS响应计算，涉及最基本的散射活性公式。获得的令人鼓舞的结果验证了计算强度较低的过程，并允许其扩展到第二个理论上的同构者的INS谱的计算，尽管在结构和能量上是合理的，但实际上并不是固态的。第二种结构是通过在构象空间中运行的蒙特卡罗模拟退火方法生产的（该过程在半经验水平上本来是昂贵的），并且其特征在于分子内氢键的程度高于X射线结构。这两种替代结构可产生不同的模拟光谱，其中只有一种是真实的，与实验数据兼容。两种模拟光谱和实验光谱的比较提供了在略高于700 cm（-1）的区域中正确的氢弯曲模体的非弹性中子散射光谱特征的标识。这项研究表明，模拟的INS数据和实验结果的组合可以成功地用于区分大型功能分子系统中不同的提议结构或可能的氢键基序，（C）1998年美国物理研究所。 [S0021-9606（98）30948-4]。 [参考：30]

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