Arkhipov Sergey G, Zakharov Boris A, Boldyreva Elena V
REC-008, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russian Federation.
Acta Crystallogr C. 2013 May;69(Pt 5):517-21. doi: 10.1107/S0108270113006720. Epub 2013 Apr 9.
L-serinium semi-maleate, (I), and DL-serinium semi-maleate, (II), both C3H8NO3(+)·C4H3O4(-), provide the first example of chiral and racemic anhydrous serine salts with the same organic anion. A comparison of their crystal structures with each other, with the structures of the pure components (L-serine polymorphs, DL-serine and maleic acid) and with other amino acid maleates is important for understanding the formation of the crystal structures, their response to variations in temperature and pressure, and structure-property relationships. As in other known crystal structures of amino acid maleates, there are no direct links between the semi-maleate anions in the two new structures. The serinium cations have different conformations in (I) and (II). In (I), they are linked into infinite chains via hydrogen bonds between carboxylic acid and hydroxy groups. In (II), there are no such chains formed by the serinium cations. In both (I) and (II), there are C2(2)(12) chains consisting of alternating semi-maleate anions and serinium cations. Two types of such chains are present in (I) and (II), termed C2(2)(12) and C2(2)(12)'. In (I), these chains, lying in the same plane, are further linked to each other via hydrogen bonds, whereas in (II) they are not.
L-丝氨酸半马来酸盐（I）和DL-丝氨酸半马来酸盐（II），化学式均为C3H8NO3(+)·C4H3O4(-)，是首例具有相同有机阴离子的手性和外消旋无水丝氨酸盐。将它们彼此的晶体结构、与纯组分（L-丝氨酸多晶型物、DL-丝氨酸和马来酸）的结构以及与其他氨基酸马来酸盐的结构进行比较，对于理解晶体结构的形成、它们对温度和压力变化的响应以及结构-性质关系具有重要意义。与其他已知的氨基酸马来酸盐晶体结构一样，这两种新结构中的半马来酸根阴离子之间没有直接联系。丝氨酸阳离子在（I）和（II）中具有不同的构象。在（I）中，它们通过羧酸和羟基之间的氢键连接成无限链。在（II）中，丝氨酸阳离子没有形成这样的链。在（I）和（II）中，都存在由交替的半马来酸根阴离子和丝氨酸阳离子组成的C2(2)(12)链。（I）和（II）中存在两种这样的链，分别称为C2(2)(12)和C2(2)(12)'。在（I）中，这些位于同一平面的链通过氢键进一步相互连接，而在（II）中它们则没有。
