The incorporation of fluorine into amino acids is an important strategy to produce tailored building blocks with unique properties for peptide-based materials. Phenylalanine is frequently modified due to its role in cation–π interactions and the formation of amyloid fibres. Previous studies have utilized gas-phase vibrational spectroscopy to study interactions between canonical amino acids. In this study, we employ a combination of cryogenic gas-phase infrared spectroscopy and density functional theory to study the interactions in proton-bound dimers of side-chain fluorinated phenylalanines. Our findings reveal how the position and number of fluorine atoms affect the interactions and structures of the dimers. Monofluorinated phenylalanines adopt charge-solvated structures in which the two amino acids interact via their ammonium and amine functions (NH₃⁺⋯NH₂). The dimer with the perfluorinated side chain forms multiple charge-solvated and salt-bridged structures with varying interaction types. These structural changes are attributed to the significant reduction of electron density in the aromatic systems.

中文翻译：

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侧链氟化对质子结合苯丙氨酸二聚体的影响：低温红外光谱研究


将氟掺入氨基酸是为肽基材料生产具有独特性能的定制结构单元的重要策略。苯丙氨酸由于其在阳离子-π相互作用和淀粉样蛋白纤维形成中的作用而经常被修饰。以前的研究利用气相振动光谱来研究经典氨基酸之间的相互作用。在这项研究中，我们采用低温气相红外光谱和密度泛函理论的组合来研究侧链氟化苯丙氨酸质子结合二聚体中的相互作用。我们的研究结果揭示了氟原子的位置和数量如何影响二聚体的相互作用和结构。单氟苯丙氨酸采用电荷溶剂化结构，其中两个氨基酸通过其铵和胺功能相互作用 （NH₃⁺⋯NH₂）。具有全氟侧链的二聚体形成具有不同相互作用类型的多个电荷溶剂化和盐桥结构。这些结构变化归因于芳香族系统中电子密度的显着降低。