Unimolecular Fragmentation of Deprotonated Diproline [Pro2-H]- Studied by Chemical Dynamics Simulations and IRMPD Spectroscopy

Ana Martin-Somer, Jonathan Martens, Josipa Grzetic, William L. Hase, Jos Oomens, Riccardo Spezia

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Dissociation chemistry of the diproline anion [Pro2-H]- is studied using chemical dynamics simulations coupled with quantum-chemical calculations and RRKM analysis. Pro2- is chosen due to its reduced size and the small number of sites where deprotonation can take place. The mechanisms leading to the two dominant collision-induced dissociation (CID) product ions are elucidated. Trajectories from a variety of isomers of [Pro2-H]- were followed in order to sample a larger range of possible reactivity. While different mechanisms yielding y1- product ions are proposed, there is only one mechanism yielding the b2- ion. This mechanism leads to formation of a b2- fragment with a diketopiperazine structure. The sole formation of a diketopiperazine b2 sequence ion is experimentally confirmed by infrared ion spectroscopy of the fragment anion. Furthermore, collisional and internal energy activation simulations are used in parallel to identify the different dynamical aspects of the observed reactivity.

Original languageEnglish
Pages (from-to)2612-2625
Number of pages14
JournalJournal of Physical Chemistry A
Volume122
Issue number10
DOIs
StatePublished - Mar 15 2018

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