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Vibrational circular dichroism of a 2,5‐diketopiperazine (DKP) peptide: Evidence for dimer formation in cyclo LL or LD diphenylalanine in the solid state
Author(s) -
PérezMellor Ariel,
Zehnacker Anne
Publication year - 2017
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.22674
Subject(s) - chemistry , dimer , diastereomer , circular dichroism , vibrational circular dichroism , crystallography , hydrogen bond , stereochemistry , molecule , organic chemistry
The diastereomer diketopiperazine (DKP) peptides built on phenylalanine, namely, cyclo diphenylalanine LPhe‐LPhe and LPhe‐DPhe, were studied in the solid phase by vibrational circular dichroism (VCD) coupled to quantum chemical calculations. The unit structure of cyclo LPhe‐LPhe in KBr pellets is a dimer bridged by two strong NH…O hydrogen bonds. The intense bisignate signature in the CO stretch region is interpreted in terms of two contributions arising from the free COs of the dimer and the antisymmetrical combination of the bound COs. In contrast, cyclo LPhe‐DPhe shows no VCD signal in relation to its symmetric nature.