一个全面的溶解物-介质相互作用模型用于异构型NMR数据预测
1Analytical Research and Development, Pfizer Worldwide Research and Development, 445 Eastern Point Road, Groton, CT 06340, USA. Yizhou.Liu@pfizer.com.
Physical chemistry chemical physics : PCCP
|February 4, 2025
概括
一个新的模型使用溶液-介质相互作用预测分子对齐,通过核磁共振 (NMR) 数据改善结构阐明. 这种方法提高了对准介质中的分子的预测.
科学领域:
- * 生物物理化学 生物物理化学
- * 结构生物学 * 结构生物学
- * 计算化学 计算机化学
背景情况:
- * 预测分子结构对于理解生物过程至关重要.
- * 非同位素核磁共振 (NMR) 数据为分子结构提供了独特的见解.
- *目前用于在对齐介质中预测NMR数据的方法存在局限性.
研究的目的:
- * 开发一种针对异构型NMR数据的综合预测模型.
- *为了准确地模拟稀释对齐介质中的溶液-介质相互作用.
- * 改进使用NMR进行分子结构阐明的过程.
主要方法:
- * 开发了一个基于溶液-介质相互作用的预测模型,包括排斥力,分散力和静电力.
- * 使用介质特定参数作为适合分子间相互作用的变量.
- * 在表面分解框架中实现了模型,用于中介诱导的溶液对齐.
- *将与隐性溶剂的相互作用纳入模型.
主要成果:
- *新型号的性能明显优于原来的硬体模型,特别是在强大的静电和分散相互作用方面.
- * 该模型准确地预测了顺序参数和异构型NMR数据.
- * 展示了一种方法来提取对齐介质聚合物的物理性质.
结论:
- * 开发的模型提供了一种可靠的方法来预测异构型NMR数据.
- * 这种方法提高了对具有挑战性的分子结构阐明的能力.
- * 该模型提供了一种概括的策略,用于表征对齐介质,并预测各种分子的NMR数据.
相关概念视频
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
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Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
998
01:17Chemical Shift: Internal References and Solvent Effects
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In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
591
01:14NMR Spectrometers: Resolution and Error Correction
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When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
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01:08NMR Spectroscopy: Spin–Spin Coupling
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The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
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01:13¹H NMR: Complex Splitting
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A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
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01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
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In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the...
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