Gessmann Renate, Brückner Hans, Petratos Kyriacos
IMBB-FORTH, 70013 Heraklion, Greece.
Department of Food Sciences, Interdisciplinary Research Center, Justus-Liebig-University of Giessen, 35392 Giessen, Germany.
Acta Crystallogr E Crystallogr Commun. 2018 Jul 27;74(Pt 8):1173-1177. doi: 10.1107/S2056989018010745. eCollection 2018 Aug 1.
Both deprotonated and neutral achiral title dipeptides assume similar structures of two conformations, which are related by a unit-cell inversion centre. Two mol-ecules of both conformations of the metal-free neutral dipeptide are linked by two hydrogen bonds, while two mol-ecules of both conformations of the ionized form coordinate a calcium ion in calcium(II) bis-[2-(2-{[(benz-yl-oxy)carbon-yl]amino}-acetamido)-2-methyl-propano-ate] monohydrate, 0.5Ca·CHNO·0.5HO, which lies on an inversion centre and forms a distorted octa-hedral complex with the metal ion. These Ca complexes are connected in the crystal hydrogen bonds in the - and -axis directions, whereas in the -axis direction, they stack apolar contacts. In the metal-free crystal, namely 2-(2-{[(benz-yloxy)carbon-yl]amino}-acetamido)-2-methyl-propanoic acid, CHNO, mol-ecules are hydrogen bonded in the - and -axis directions, and stack in the -axis direction apolar contacts.
去质子化和中性的非手性标题二肽都呈现出两种构象的相似结构，这两种构象通过晶胞反演中心相互关联。无金属中性二肽的两种构象的两个分子通过两个氢键相连，而离子化形式的两种构象的两个分子在一水合钙（II）双-[2-(2-{[(苄氧基)羰基]氨基}-乙酰胺基)-2-甲基-丙酸酯]，0.5Ca·C₁₇H₂₅NO₅·0.5H₂O中配位一个钙离子，该钙离子位于一个反演中心上，并与金属离子形成一个扭曲的八面体配合物。这些钙配合物在晶体中沿a和b轴方向通过氢键相连，而在c轴方向上，它们通过非极性接触堆积。在无金属晶体中，即2-(2-{[(苄氧基)羰基]氨基}-乙酰胺基)-2-甲基-丙酸，C₁₇H₂₅NO₅，分子在a和b轴方向上通过氢键相连，并在c轴方向上通过非极性接触堆积。
