The peptide NCbz-Val-Tyr-OMe and aromatic π-π interactions.

The peptide N-benzyloxycarbonyl-L-valyl-L-tyrosine methyl ester or NCbz-Val-Tyr-OMe (where NCbz is N-benzyloxycarbonyl and OMe indicates the methyl ester), C(23)H(28)N(2)O(6), has an extended backbone conformation. The aromatic rings of the Tyr residue and the NCbz group are involved in various attractive intra- and intermolecular aromatic π-π interactions which stabilize the conformation and packing in the crystal structure, in addition to N-H...O and O-H...O hydrogen bonds. The aromatic π-π interactions include parallel-displaced, perpendicular T-shaped, perpendicular L-shaped and inclined orientations.