M. Cetina, A. Hergold-Brundić, N. Raos
Sep 1, 2003
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Influential Citations
2
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract The crystal structure of (1SR, 2RS)-1-[N-tert-butoxycarbonyl)amino]-2-hydroxymethylcylopropane-1-carboxylic acid, a derivative of 1-aminocyclopropanecarboxylic acid (Acc), was determined by X-ray analysis. The molecule possesses the Z-configuration of the cyclopropane ring, a disordered carboxylic group, and a trans conformation of peptide bond. Intermolecular hydrogen bonds form R22(8) and R22(10) dimers and infinite chains along the b-axis. Mutually connected molecules are in ab-plane separated by the hydrophobic channels formed between tert-butyl groups of adjacent molecules. Conformational analysis using molecular-mechanics method, supported by the overlapping spheres method for finding the low-energy conformations, showed that the conformation observed in crystal state had 2.8 kJ mol−1 higher conformational energy than the lowest conformation. The analysis also showed that there were at least 11 conformations within that span, which is consistent with the assumption that the conformation of this molecule in the crystal state is substantially influenced by hydrogen bonding. Calculations for the dimer consisting of x,y,z and x,y−1,z molecule showed a high correlation between the reproduction of crystal structure and similarity of its monomer units, which suggests that the symmetry of the dimer is not caused merely by crystal packing.