Crystal structure and spectroscopic properties of cyclic dipeptide: A racemic mixture of cyclo(D-Prolyl-L-Tyrosyl) and cyclo(L-Prolyl-D-Tyrosyl)

Yong Pyo Hong, Sung Hong Lee, Jong Ha Choi, Ayana Kashima, Go Nakamura, Takayoshi Suzuki

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Two diastereoisomers of cyclo(Pro-Tyr) have been synthesized simultaneously. The crystal structures and conformations of both cyclo(L-Pro-L-Tyr) and a racemic mixture of cyclo(D-Pro-L-Tyr) and cyclo(L-Pro-DTyr), abbreviated as rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr), have been determined by a single-crystal X-ray diffraction study at low temperature. The crystals of rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr) belong to orthorhombic space group Pna21 with a = 10.755 (1), b = 12.699 (1), c = 9.600 (1) Å and Z = 4. The tyrosine side chain is folded towards the diketopiperazine (DKP) ring. The DKP ring adopts a twist boat conformation with pseudo symmetry C2v. The pyrrolidine ring has an envelope conformation with the N5, C4, C7 and C8 atoms in a plane. The crystal of rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr) is stabilized by hydrogen bonds between amide N2-H2 and carbonyl oxygen O2 in the neighbor. The hydroxyl group of tyrosine residue is also hydrogen bonded to the oxygen of the carbonyl group of the DKP ring in the next molecule. The spectroscopic properties of both isomers are also described.

Original languageEnglish
Pages (from-to)2299-2303
Number of pages5
JournalBulletin of the Korean Chemical Society
Issue number8
Publication statusPublished - Aug 20 2014



  • Conformation
  • Crystal structure
  • Cyclic dipeptide
  • Rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr)
  • Spectral data

ASJC Scopus subject areas

  • Chemistry(all)

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