Reinvestigation of L-tryptophan picrate: Establishment of the existence of the L-tryptophan L-tryptophanium dimeric cation

摘要

A crystal structure redetermination of the L-tryptophan picrate crystal previously studied by Ishida et al. (Chem. Pharm. Bull. 41 (1993) 433-438) showed that it comprises L-tryptophan L-tryptophanium dimeric cation, one picrate anion and picric acid. The O?O distance of the O-H?O hydrogen bond in the dimeric cation is equal to 2.470(6) ?. The infrared spectrum of the crystal was registered and analyzed. The infrared spectrum of the crystals contains a broad absorption band centered at ca. 1170 cm ~(-1), which is assigned to the stretching vibration of the O-H bond.