Surface-induced dissociation of singly and multiply protonated polypropylenamine dendrimers |
| |
Authors: | Janine de Maaijer-Gielbert Chungang Gu Árpád Somogyi Vicki H. Wysocki Piet G. Kistemaker Tina L. Weeding |
| |
Affiliation: | FOM-institute for Atomic and Molecular Physics, Kruislaan, SJ Amsterdam, The Netherlands. |
| |
Abstract: | The ease of fragmentation of various charge states of protonated polypropylenamine (POPAM) dendrimers is investigated by surface-induced dissociation. Investigated are the protonated diaminobutane propylenamines [DAB(PA)n] DAB(PA)8 (1+ and 2+), DAB(PA)16 (2+ and 3+), and DAB(PA)32 (3+ and 4+). These ions have been proposed to fragment by charge-directed intramolecular nucleophilic substitution (SNi) reactions. Differences in relative fragment ion abundances between charge states can be related to the occupation of different protonation sites. These positions can be rationalized based on estimates of Coulomb energies and gas-phase basicities of the protonation/fragmentation sites. The laboratory collision energies at which the fragment ion current is approximately 50% of the total ion current were found to increase with the size, but to be independent of charge state of the protonated POPAM dendrimers. It is suggested that intramolecular Coulomb repulsion within the multiply protonated POPAM dendrimers selected for activation does not readily result in easier fragmentation, which is in accordance with the proposed fragmentation mechanism. |
| |
Keywords: | |
本文献已被 ScienceDirect PubMed SpringerLink 等数据库收录! |
|