An Experimental and Theoretical Investigation of Gas‐Phase Reactions of Ca 2+ with Glycine

• Published in: Chemistry : a European journal 2006-09, Vol.12 (26), p.6787-6796
• Main Authors: Corral, Inés, Mó, Otilia, Yáñez, Manuel, Salpin, Jean‐Yves, Tortajada, Jeanine, Moran, Damian, Radom, Leo
• Format: Article
• Language: English
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200600127

The gas‐phase reactions between Ca 2+ and glycine ([Ca(gly)] 2+ ) have been investigated through the use of mass spectrometry techniques and B3‐LYP/cc‐pWCVTZ density functional theory computations. The major peaks observed in the electrospray MS/MS spectrum of [Ca(gly)] 2+ correspond to the formation of the [Ca,C,O 2 ,H] + , NH 2 CH 2 + , CaOH + , and NH 2 CH 2 CO + fragment ions, which are produced in Coulomb explosion processes. The computed potential energy surface (PES) shows that not only are these species the most stable product ions from a thermodynamic point of view, but they may be produced with barriers lower than for competing processes. Carbon monoxide is a secondary product, derived from the unimolecular decomposition of some of the primary ions formed in the Coulomb explosions. In contrast to what is found for the reactions of Ca 2+ with urea ([Ca(urea)] 2+ ), minimal unimolecular losses of neutral fragments are observed for the gas‐phase fragmentation processes of [Ca(gly)] 2+ , which is readily explained in terms of the topological differences between their respective PESs.