title: (15)N and (13)C high-resolution solid-state NMR study of the polymorphism of the L-enantiomer of N-benzoylphenylalanine.
abstract: In this paper, several approaches which allow the investigation of mixtures of polymorphs, employing modern solid-state NMR (SS NMR) spectroscopy are reported. A convenient methodology for characterization of the hydrogen bonding and molecular conformation of a polymorphic sample by means of one-dimensional and two-dimensional, 13C and 15N NMR experiments as well as CSA tensor analysis and theoretical calculations is presented. Two-dimensional heteronuclear SS NMR allowed definition of the polymorphic domain of N-benzoyl-L-phenylalanine (N-Bz-Phe). The graphical method of Herzfeld and Berger was used to measure the 13C and 15N spinning sideband intensities which allowed the calculation of NMR parameters for labeled centers of N-Bz-Phe. The experimental data were compared with computed results obtained by means of the DFT hybrid method with B3PW91 functional and 6-311++G** basis set.
authors.affiliation: Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, Lodz, Poland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Olejniczak
authors.forename: Justyna
authors.initials: J
authors.lastname: Mikuła-Pacholczyk
authors.forename: Colan E
authors.initials: CE
authors.lastname: Hughes
authors.forename: Marek J
authors.initials: MJ
authors.lastname: Potrzebowski