Issue 30, 2010

Pseudoracemic amino acid complexes: blind predictions for flexible two-component crystals

Abstract

Ab initio prediction of the crystal packing in complexes between two flexible molecules is a particularly challenging computational chemistry problem. In this work we present results of single crystal structure determinations as well as theoretical predictions for three 1 ∶ 1 complexes between hydrophobic L- and D-amino acids (pseudoracemates), known from previous crystallographic work to form structures with one of two alternative hydrogen bonding arrangements. These are accurately reproduced in the theoretical predictions together with a series of patterns that have never been observed experimentally. In this bewildering forest of potential polymorphs, hydrogen bonding arrangements and molecular conformations, the theoretical predictions succeeded, for all three complexes, in finding the correct hydrogen bonding pattern. For two of the complexes, the calculations also reproduce the exact space group and side chain orientations in the best ranked predicted structure. This includes one complex for which the observed crystal packing clearly contradicted previous experience based on experimental data for a substantial number of related amino acid complexes. The results highlight the significant recent advances that have been made in computational methods for crystal structure prediction.

Graphical abstract: Pseudoracemic amino acid complexes: blind predictions for flexible two-component crystals

Supplementary files

Article information

Article type
Paper
Submitted
09 Mar 2010
Accepted
14 Apr 2010
First published
11 May 2010

Phys. Chem. Chem. Phys., 2010,12, 8466-8477

Pseudoracemic amino acid complexes: blind predictions for flexible two-component crystals

C. H. Görbitz, B. Dalhus and G. M. Day, Phys. Chem. Chem. Phys., 2010, 12, 8466 DOI: 10.1039/C004055J

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