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Updated: Jul 1, 2025

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry
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灵活分子的多态识别:对实验和计算的溶液和固态NMR数据的线性回归分析.

Mohammed Rahman1,2, Hugh R W Dannatt3, Charles D Blundell3

  • 1Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.

The journal of physical chemistry. A
|March 1, 2024
PubMed
概括

先进的δδ回归方法准确地识别了具有多重构造的分子的固体形式,如furosemide多态,使用NMR和DFT. 这种方法提供了比RMSE更大的动态范围,用于精确的固态特性.

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¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR

The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
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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.
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Unlike small molecules with definite molecular weights, polymers are a mixture of individual polymer chains of varying lengths, each with a unique molecular weight.  So, the molecular weight of a polymer is expressed as an average value based on the average size of the polymer chains. The two most common forms of averages used for polymers are the number average molecular weight and weight average molecular weight.
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