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Solid Tryptophan as a Pseudoracemate: Physicochemical and Crystallographic Characterization
Author(s) -
Li Yan,
Zhao Yuming,
Zhang Yan
Publication year - 2015
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22399
Subject(s) - chemistry , enantiomer , differential scanning calorimetry , tryptophan , crystallography , chirality (physics) , hydrogen bond , solid state , crystal (programming language) , crystal structure , solid solution , stereochemistry , organic chemistry , molecule , thermodynamics , amino acid , biochemistry , physics , nambu–jona lasinio model , chiral symmetry breaking , quantum mechanics , computer science , programming language , quark
The crystalline nature of solid tryptophan has been characterized by X‐ray single crystal and powder diffraction analyses, differential scanning calorimetry, as well as measurement of solid–liquid equilibrium in water/isopropanol solution. Both the thermodynamic and crystallographic investigations have demonstrated unambiguously that solid tryptophan crystallizes in the form of a pseudoracemate (i.e., solid solution) with maximum melting over the entire enantiomeric composition range. Comparative single‐crystal X‐ray studies show that the crystal structures of racemic and enantiomeric tryptophan give very similar solid‐state packing geometries dictated by hydrogen bonding interactions. Our results indicate that the insignificant difference between homochiral and heterochiral interactions accounts for the formation of a pseudoracemate for this system. Chirality 27:88–94, 2015. © 2014 Wiley Periodicals, Inc.