在质子结合的离子中探测伦敦分散:基-基立体相互作用是否可靠地建模?
Vladimir Gorbachev1, Adélaïde Savoy1, Alexandra Tsybizova1
1Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich 8093, Switzerland.
这项研究使用光谱学和光谱学研究了质子化二氧化中的伦敦分散相互作用. 结果表明密度函数理论计算可能高估了三基相互作用的强度.
科学领域:
- 物理化学
- 计算化学
- 光谱学
背景情况:
- 伦敦分散力是影响分子结构和属性的关键非共价相互作用.
- 精确的分散相互作用的计算建模,特别是像特-基这样的大型基组,仍然是一个挑战.
研究的目的:
- 用实验方式探测和量化 protonated bis-pyridines 中的 tert-butyl 替代剂之间的伦敦分散相互作用.
- 评估分散校正密度函数理论 (DFT-D3BJ) 在预测涉及三基的结构和相互作用方面的性能.
主要方法:
- 气相红外多光子解离光谱分析N-H拉伸频率并推断基本状态几何.
- 捕获的离子移动性光谱测定碰撞截面,提供独立的结构读数.
- 用各种交换相关函数进行分散校正密度函数理论 (DFT-D3BJ) 的计算.
主要成果:
- 随着替代剂大小的增加,观察到伦敦分散相互作用强度的系统调节 (从H到Me到tert-Bu).
- 实验数据显示与DFT-D3BJ预测的差异,特别是在 tert-butyl-tert-butyl相互作用方面.
- 发现DFT-D3BJ计算显著过度结合基-基相互作用,在分散与结合相竞争时无法可靠地预测最小能量结构.
结论:
- 实验方法为复杂分子系统中的伦敦分散相互作用提供了可靠的见解.
- 目前的DFT-D3BJ函数可能需要精细化,以准确描述强-分散相互作用,特别是在存在竞争的非对应力的情况下.
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