Abstract Haloperidol, with molecular formula C21H23ClFNO2, is a conventional antipsychotic drug used to relieve the symptoms of schizophrenia. Although its pharmacology has been extensively reported, only few studies focused on its vibrational features. In this work, Raman spectroscopy was used to investigate the vibrational properties of the haloperidol crystal under high-pressure conditions up to approximately 5.9 GPa. Our results showed changes in the low wavenumber bands accompanied by some changes in the internal vibrational modes, indicating the occurrence of a phase transition. Analysis of the Raman spectra shows phase transitions around 2.0 GPa and 4.2 GPa, with the disappearance and appearance of some modes in addition to discontinuities in the evolution of the frequencies of several normal modes of vibration. Such changes involved modes located in the region of external modes while others involved modes of the molecular skeleton and modes that participate in hydrogen bonds. At 4.2 GPa the changes were related to small conformational changes associated with hydrogen bonds and small deformations in the haloperidol molecules. At 2.0 GPa it was observed a change corresponding to the lattice modes, indicating a structural phase transition with conformational change.

中文翻译：

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高压下氟哌啶醇的振动特性研究

摘要 氟哌啶醇分子式为C21H23ClFNO2，是一种用于缓解精神分裂症症状的常规抗精神病药物。尽管其药理学已被广泛报道，但很少有研究关注其振动特征。在这项工作中，拉曼光谱用于研究氟哌啶醇晶体在高达约 5.9 GPa 的高压条件下的振动特性。我们的结果显示低波数带的变化伴随着内部振动模式的一些变化，表明发生了相变。拉曼光谱的分析表明，相变在 2.0 GPa 和 4.2 GPa 附近，除了几种正常振动模式的频率演变中的不连续性之外，还有一些模式的消失和出现。这些变化涉及位于外部模式区域的模式，而其他变化涉及分子骨架的模式和参与氢键的模式。在 4.2 GPa 时，这些变化与氢键相关的小构象变化和氟哌啶醇分子的小变形有关。在 2.0 GPa 观察到对应于晶格模式的变化，表明结构相变与构象变化。