title: Single-crystal investigation of L-tryptophan with Z' = 16.
abstract: A complex, disorder-free structure in the space group P1 has been established for L-tryptophan, for which no crystal structure has previously been available. The 16 molecules in the asymmetric unit can be divided into two groups of eight; one where the side chains have gauche orientations and one with trans orientations. Molecules within each group have almost identical molecular geometries. The unit-cell parameters mimic a hexagonal cell, but deviations from 90° for the cell angles α = 84.421 (4) and β = 87.694 (4)° give a small tilt that rules out hexagonal symmetry. The hydrogen-bonding pattern resembles that found in the crystal structure of the racemic structure of DL-tryptophan, but a lower density combined with longer hydrogen bonds and inter-aromatic interactions show that the enantiomeric structure is less efficiently packed.
authors.affiliation: Department of Chemistry, University of Oslo, Oslo, Norway. c.h.gorbitz@kjemi.uio.no
authors.forename: Carl Henrik
authors.initials: CH
authors.lastname: Görbitz
authors.forename: Karl Wilhelm
authors.initials: KW
authors.lastname: Törnroos
authors.forename: Graeme M
authors.initials: GM
authors.lastname: Day
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D013237:Stereoisomerism; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D014364:Tryptophan