The crystal and molecular structure of 3, 4-dihydroxy L-phenyl-alanine

The molecule crystallizes in spacegroup P2₁ with two molecules per unit cell. The unit cell dimensions area = 6.044 Å,b = 13.607 Å,c = 5.311 Å,γ = 97.55°. The density was calculated to be 1.512 g.ml.^?1 and found to be 1.51 g.ml.^?1 The major atoms were located by the reliable image method and the hydrogen atoms were located from a difference electron density map. Full-matrix least squares refinement of the parameters yielded an unweighted residual indexR of 0.088. The bond lengths and angles of the amino acid grouping are consistent with values in other amino acids. The structural parameters of the aromatic system are very similar to those of noradrenaline and dopamine hydrochlorides. The crystal structure is dominated by a three-dimensional intermolecular hydrogen bonding system. The molecular conformation is different from that displayed by any other aromatic amino acid or peptide whose crystal structure is known.