Single‐crystal investigation of l‐tryptophan with Z′ = 16
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.