Glycine molecular geometry

After optimization of the molecular geometry the resulted geometry of IVa displayed the distinctive arrangement of water molecules (Fig. 10.3). In this optimized stmcture the triiodide interacts with the amino groups of the two Gly-Gly pairs, without participation of water molecules. The location of coordination of LiCl-ethanol has been also altered. A LiCl-ethanol fragment coordinates the car-boxy group of the third Gly-Gly pair, which does not interact with 13 . A new OH-bond was formed in the glycine molecule, clear of coordination in the Gly-Gly pair that interacted with LiCl-ethanol. 

Then, as case study, we consider the glycine and glycyl radicals (Fig. 6.2) in solution. As mentioned above, the calculation of magnetic tensors needs to take into account the several factors such as the geometries, environmental effects, and dynamical effects (vibrational averaging from intramolecular vibrations and/or solvent librations). We use an integrated computational approach where the molecular... 

Chemical Shift and its Anisotropy Spin 1/2 Nuclei. - Calculations of NMR chemical shifts in crystalline phases of some representative amino acids such as glycine, alanine, and alanyl-alanine have been reported. The effect of environment on the chemical shifts was explored in selected glycine geometries ranging from the crystalline phase to completely isolated molecules. In the crystalline and dilute molecular limits, the calculated distinct NMR chemical shifts have been attributed to intermolecular hydrogen bonds and dipole electric field effects, respectively. 

The glycine and alanine dipeptide analogs (GDA and ADA) have recently garnered theoretical attention, because they are the two simplest models of a polypeptide. Molecular mechanical force fields designed to model proteins are often parameterized to reproduce, as well as possible, the geometries and relative energies of the various GDA and ADA conformers. Since few experimental data are available, one must rely on theoretical studies. To date, DFT calculations on peptides have been limited to GDA and ADA. ... 

---