Acta Cryst. (2003). E59, o952-o954  [ doi:10.1107/S1600536803011942 ]

L-Phenylalanine fumaric acid

M. Alagar, R. V. Krishnakumar, K. Rajagopal, M. Subha Nandhini and S. Natarajan

Abstract: In the title adduct, C₉H₁₁NO₂·C₄H₄O₄, the amino acid molecules exist as zwitterions and the fumaric acid molecules exist in the unionized state, a feature uncommon in similar crystal structures. The asymmetric unit is composed of two molecules of each species. The fumaric acid molecules are related to each other through a pseudo-inversion centre and are essentially planar. The phenylalanine and fumaric acid molecules form hydrogen-bonded double layers, linked together by hydrogen bonds and extending along [001]. These double layers are flanked, on either side, by the hydrophobic side chains of phenylalanine, leading to alternating hydrophilic and hydrophobic zones.

Online 17 June 2003

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