Abstract

First-principles studies of the potential energy profiles for dissociation of poly[(R, S)-3-hydroxybutanoic acid] [PHB n -H] − anions by proton rearrangement and direct fragmentation, as well as subsequent statistical RRKM analysis, indicate that fragmentation should proceed mainly through successive loss of a single 86 Da neutral unit (propene + CO 2). This theoretically predicted fragmentation mechanism is inconsistent with that proposed in the literature based on experiments, which suggests that proton rearrangements are the only active fragmentation channels in CID of [PHB n -H] −. We have combined experimental ESI-MS/MS fragmentation studies of [PHB n -H] − with first-principles explorations of the potential energy surfaces, and molecular dynamics simulations of CID and thermal fragmentation events to understand this discordance. Both proton rearrangement and direct fragmentation channels are considered. The results reveal that the fragmentations observed at low collision energy favor the direct fragmentation channel and are more closely modeled as a thermal fragmentation process. By contrast, fragmentations observed at higher collision energy favor the indirect fragmentation channels and are more closely modeled as a fast CID process.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.