Discrimination of Glycine Enantiomers by the Biologically Important Phosphocompounds:A Theoretical Prediction

With the aid of high-level B3LYP and MP2 calculations, three new neutral structures of glycine (iin, ivn and vn, see Fig. 2) were obtained and validated by frequency calculations. The structural and energetic analyses showed that iin, ivn and vn are enantiomers to the previous IIn, IVn and Vn (J. Am. Chem. Soc. 1992, 114, 9568.), respectively. Owing to the presence of these novel conformers, a redistribution of the populations of glycine conformers is resulted in and causes the remarkable decrease of the most stabilized Ip (from 48% to 38%). It indicated that the simple glycine molecule can show chirality under certain conditions. The interacting modes of glycine enantiomeric pairs (e.g., ivn and IVn) with PG showed large differences (Fig. 4); in addition, their interaction energies corrected with basis set superposition errors (BSSE) were calculated to be -66.81 and -46.99 kJ mol-1, respectively. Accordingly, the glycine enantiomers can be potentially applied to the chiral recognition in biological and pharmaceutical areas.