Safferthal Marc, Greis Kim, Chang Rayoon, Kirschbaum Carla, Hoffmann Waldemar, Meijer Gerard, von Helden Gert, Pagel Kevin
Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Altensteinstraße 23a, 14195 Berlin, Germany.
Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
Phys Chem Chem Phys. 2023 Sep 20;25(36):24783-24788. doi: 10.1039/d3cp03776b.
In past decades, hydrogen bonds involving organic fluorine have been a highly disputed topic. Obtaining clear evidence for the presence of fluorine-specific interactions is generally difficult because of their weak nature. Today, the existence of hydrogen bonds with organic fluorine is widely accepted and supported by numerous studies. However, strong bonds with short H⋯F distances remain scarce and are primarily found in designed model compounds. Using a combination of cryogenic gas-phase infrared spectroscopy and density functional theory, we here analyze a series of conformationally unrestrained fluorinated phenylalanine compounds as protonated species. The results suggest proximal NH⋯F hydrogen bonds with an exceptionally close H⋯F distance (1.79 Å) in protonated -fluorophenylalanine.
在过去几十年里，涉及有机氟的氢键一直是一个备受争议的话题。由于氟特异性相互作用性质较弱，通常很难获得其存在的确切证据。如今，与有机氟形成氢键的存在已被广泛接受，并得到了大量研究的支持。然而，具有短H⋯F距离的强键仍然很少见，主要存在于设计的模型化合物中。我们结合低温气相红外光谱和密度泛函理论，在此分析了一系列构象不受限制的氟化苯丙氨酸化合物作为质子化物种。结果表明，在质子化的-氟苯丙氨酸中存在近端NH⋯F氢键，其H⋯F距离异常短（1.79 Å）。
