Vibrational circular dichroism as a probe of solid-state organisation of derivatives of cyclic β-amino acids: Cis- and trans-2-aminocyclobutane-1-carboxylic acid.

Vibrational circular dichroism as a probe of solid-state organisation of derivatives of cyclic β-amino acids: Cis- and trans-2-aminocyclobutane-1-carboxylic acid. Chirality. 2019 Jun 26;: Authors: Declerck V, Pérez-Mellor A, Guillot R, Aitken DJ, Mons M, Zehnacker A Abstract Peptide models built from cis- and trans-2-aminocyclobutane-1-carboxylic acids (ACBCs) are studied in the solid phase by combining Fourier-transform infrared spectroscopy (FTIR) absorption spectroscopy, vibrational circular dichroism (VCD), and quantum chemical calculations using density functional theory (DFT). The studied systems are N-tert-butyloxycarbonyl (Boc) derivatives of 2-aminocyclobutanecarboxylic acid (ACBC) benzylamides, namely Boc-(cis-ACBC)-NH-Bn and Boc-(trans-ACBC)-NH-Bn. These two diastereomers show very different VCD signatures and intensities, which of the trans-ACBC derivative being one order of magnitude larger in the region of the ν (CO) stretch. The spectral signature of the cis-ACBC derivative is satisfactorily reproduced by that of the monomer extracted from the solid-state geometry of related ACBC derivatives, which shows that no long-range effects are implicated for this system. In terms of hydrogen bonds, the geometry of this monomer is intermediate between the C6 and C8 structures (exhibiting a 6- or 8-membered cyclic NH⋯O hydrogen bond) previously evidenced in the gas phase. The benzyl group must be in an extended geometry to r...
Source: Chirality - Category: Molecular Biology Authors: Tags: Chirality Source Type: research