Towards an understanding of the CO2-philicity in glycine: Deepening into the CO2:Aminoacid interactions

Abstract

The potential energy surface (PES) for the CO2:glycine complexes were thoroughly examined by means of the MP2/aug-cc-pVDZ computational level. Heterodimers exhibit non-covalent interactions holding monomers together primarily by Xlp···CO2 (X=O, N) tetrel bonds and, in some binary complexes, by additional OCOlp···HY (Y=O, N) H-bonds. Non-classical CH···O H-bonds are also present in some cases as secondary interactions. Binding energies are between −3.00 and up to −5.29kcal/mol, being for the most stable complexes comparable with the one obtained for the paradigmatic water dimer. Partitioning of the interaction energy points to electrostatic as the prime contribution to the stability with an important dose of dispersion. Electron density shifts reveal a gain of electron density associated to the tetrel bond acceptor, whereas the donor moiety experiences a loss.