Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway).
Angew Chem Int Ed Engl. 2014 Dec 1;53(49):13600-4. doi: 10.1002/anie.201406886. Epub 2014 Oct 21.
The solid-state structure of the amino acid phenylalanine (Phe) offers a potential key to understanding the behavior of a large class of important aromatic compounds. Obtaining good single crystals is, however, notoriously difficult. The structure of the common polymorph of Phe, form I, was first reported by Weissbuch et al. (as D-Phe) in 1990, but the correctness of the published C2 unit cell with two disordered molecules in the asymmetric unit was later questioned and other space groups suggested. The identity of form I of L-Phe is here established to be P21 with Z'=4, based on data from a well-diffracting single crystal grown from an acetic acid solution of the amino acid. A second new polymorph, form IV, together with the two recently described forms II and III provide unprecedented information on the structural complexity of this essential amino acid. It is furthermore documented that the racemate, dl-Phe, does not grow proper single crystals.
氨基酸苯丙氨酸（Phe）的固态结构为理解一大类重要芳香族化合物的行为提供了一个潜在的关键。然而，获得良好的单晶却是出了名的困难。常见多晶型物 Phe 的结构 I 最早由 Weissbuch 等人（以 D-Phe 形式）于 1990 年报道，但随后对发表的 C2 晶胞提出了质疑，认为其中有两个无序分子位于不对称单元中，且还有其他空间群的建议。基于从氨基酸的乙酸溶液中生长的衍射良好的单晶数据，这里确定 L-Phe 的形式 I 为 P21，Z'=4。此外，还发现了第二种新的多晶型物 IV 形式，以及最近描述的 II 和 III 两种形式，为这种必需氨基酸的结构复杂性提供了前所未有的信息。此外，还证明外消旋 dl-Phe 不能生长出合适的单晶。
