升温及紫外辐射对亚油酸分子结构的影响：衰减全反射红外光谱和二维相关光谱法研究。

Effect of elevated temperature and UV radiation on molecular structure of linoleic acid by ATR-IR and two-dimensional correlation spectroscopy.

机构信息

Department of Biomedical Engineering, Wrocław University of Science and Technology, pl. Grunwaldzki 13, 50-370 Wrocław, Poland.

Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland.

出版信息

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Sep 5;238:118436. doi: 10.1016/j.saa.2020.118436. Epub 2020 May 1.

DOI:10.1016/j.saa.2020.118436

PMID:32403075

Abstract

The effect of elevated temperature (44 °C) and ultraviolet (UV) radiation on molecular structure of linoleic acid (LA) was studied by Attenuated Total Reflection Infrared (ATR-IR) spectroscopy. To obtain more detailed information on molecular mechanism of these changes we applied moving-window analysis and two-dimensional correlation spectroscopy (2DCOS). Analysis of the time-dependent ATR-IR spectra of LA before and after UV irradiation revealed the structural changes in molecules of LA. The extent of these changes was significantly higher after an application of UV radiation. During 24 h experiment temperature was constant, therefore the spectral changes result from relatively slow processes (and requiring more energy), e.g. cis/trans isomerization, disruption of the C=C double bonds and partial breaking of hydrogen bonds in the cyclic dimers. As a side effect of these structural changes one can observe variations in the orientation of the chains. It is of note that the methyl and methylene groups reveal slightly different behaviour.

摘要

采用衰减全反射红外光谱（ATR-IR）技术研究了高温（44°C）和紫外线（UV）辐射对亚油酸（LA）分子结构的影响。为了更详细地了解这些变化的分子机制，我们应用了移动窗口分析和二维相关光谱（2DCOS）。对 LA 在 UV 照射前后的时间相关 ATR-IR 光谱进行分析，揭示了 LA 分子结构的变化。在应用 UV 辐射后，这些变化的程度明显更高。在 24 小时的实验中，温度保持不变，因此光谱变化源于相对较慢的过程（需要更多的能量），例如顺/反式异构化、C=C 双键的破坏以及环状二聚体中氢键的部分断裂。作为这些结构变化的副作用，可以观察到链的取向的变化。值得注意的是，甲基和亚甲基基团表现出略有不同的行为。