X-ray and 13C solid-state NMR studies of N-benzoylphenylalanine

A crystalline sample of N-benzoyl-DL-phenylalanine 1 and a polycrystalline sample of N-benzoyl-L-phenylalanine 2 were studied using C-13 high-resolution solid-state NMR spectroscopy. The X-ray structure of the DL form was established. Sample 1 crystallizes in a monoclinic form with a P2(1)/c space group, a=11.338(1) Angstrom, b=9.185(1) Angstrom, c=14.096(2) Angstrom, beta=107.53(3)degrees, V=1400(3) Angstrom(3), Z=4 and R=0.053. The principal elements of the C-13 chemical shift tensors delta(ii) for 1 and 2, selectively C-13 (99%) labeled at the carboxyl groups were calculated. On the basis of C-13 delta(ii) analysis the hydrogen bonding pattern for sample 2 was deduced. Enriched samples were used to establish the intermolecular distance between chemically equivalent nuclei for 1 and spatial proximity in heterogeneous domain for 2, employing the ODESSA pulse sequence. The consistence of the complementary approach covering X-ray data, analysis of the C-13 delta(ii) parameters and ODESSA results is revealed.