Dobšíková Kristýna, Michal Pavel, Spálovská Dita, Kuchař Martin, Paškanová Natalie, Jurok Radek, Kapitán Josef, Setnička Vladimír
Department of Analytical Chemistry, University of Chemistry and Technology, Prague 6, 166 28, Czech Republic.
Department of Optics, Palacký University Olomouc, Olomouc, 771 46, Czech Republic.
Analyst. 2023 Mar 13;148(6):1337-1348. doi: 10.1039/d2an02014a.
After cannabis, the most commonly used illicit substance worldwide is amphetamine and its derivatives, such as methamphetamine, with an ever-increasing number of synthetic modifications. Thus, fast and reliable methods are needed to identify them according to their spectral patterns and structures. Here, we have investigated the use of molecular spectroscopy methods to describe the 3D structures of these substances in a solution that models the physiological environment. The substances were analyzed by Raman and infrared (IR) absorption spectroscopy and by chiroptical methods, vibrational circular dichroism (VCD) and Raman optical activity (ROA). The obtained experimental data were supported by three different computational approaches based on density functional theory (DFT) and molecular dynamics (MD). Successful interpretation relies on good agreement between experimental and predicted spectra. The determination of the conformer populations of the studied molecules was based on maximizing the similarity overlap of weighted conformer spectra by a global minimization algorithm. Very good agreement was obtained between the experimental spectra and optimized-population weighted spectra from MD, providing a detailed insight into the structure of the molecules and their interaction with the solvent. The relative population of three amphetamine and six methamphetamine conformers was determined and is consistent with a previous NMR study. However, this work shows that only a few isolated conformers are not sufficient for the successful interpretation of the spectra, but the entire conformational space needs to be sampled appropriately and explicit interaction with the solvent needs to be included.
除大麻外，全球最常用的非法物质是苯丙胺及其衍生物，如甲基苯丙胺，其合成变体数量不断增加。因此，需要快速可靠的方法根据其光谱模式和结构来识别它们。在此，我们研究了使用分子光谱方法来描述这些物质在模拟生理环境的溶液中的三维结构。通过拉曼光谱和红外（IR）吸收光谱以及手性光谱方法、振动圆二色性（VCD）和拉曼光学活性（ROA）对这些物质进行了分析。所获得的实验数据得到了基于密度泛函理论（DFT）和分子动力学（MD）的三种不同计算方法的支持。成功的解释依赖于实验光谱和预测光谱之间的良好一致性。所研究分子构象体群体的测定基于通过全局最小化算法最大化加权构象体光谱的相似性重叠。实验光谱与MD优化群体加权光谱之间取得了非常好的一致性，从而详细洞察了分子结构及其与溶剂的相互作用。确定了三种苯丙胺和六种甲基苯丙胺构象体的相对群体，这与先前的核磁共振研究一致。然而，这项工作表明，仅几个孤立的构象体不足以成功解释光谱，而是需要对整个构象空间进行适当采样，并纳入与溶剂的明确相互作用。
