Elucidation of Fragmentation Pathways of Nitrile-Terminated PPI Dendrimer-Metal Complexes

Author

Kristen Nicole PackFollow

Date of Award

2010

Degree Name

Chemistry

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

William D. Price

Second Advisor

Leslie Frost

Third Advisor

B. Scott Day

Abstract

The complexity of branching macromolecules around a core unit, such as poly(propylene)imine (PPI) dendrimers, has caught the attention of researchers for several years^1,2,3,4,5. The structural framework of the core unit for these dendrimers is simply 1,4- diaminobutane. As the synthesis of higher-order generations of the macromolecule progresses, the molecules become very complex and tightly woven, but have predictable geometries and properties. The PPI dendrimers can be functionalized at the terminal ends of the branches in order to elicit different properties. The PPI dendrimer examined in this project has been terminated with a nitrile group rather than the usual amine group. Using mass spectrometry, the gas-phase fragmentation pathways under low energy collision conditions of the modified PPI dendrimer complexed with transition and alkali metals will be examined. The current project focuses on the fragmentation pathways of complexes consisting of alkali and transition metals with first and second-generation nitrile-terminated PPI dendrimers. The current project also utilizes a ¹⁵N-labeled nitrile-terminated first generation PPI dendrimer for comparison with the unlabeled first generation dendrimer fragmentation pathways. The dendrimers are synthesized in-house using 1,4-diaminobutane and acrylonitrile. Deuterium-labeled dendrimers are synthesized from d4-succinonitrile and d₄-succinamide and reduced using LAD and LAH. The fragmentation pathways for the metal-dendrimer complexes tend to follow a similar pattern, with acetonitrile and acrylonitrile as the primary neutral losses. The complexes also utilize a radical mechanism for the loss of acetonitrile, with the nickel complex being an exception. The overall ease and efficiency of the elucidation of these fragmentation pathways makes mass spectrometry a very valuable method of analysis for these dendrimer-metal complexes.

Subject(s)

Fragmentation reactions.

Dendrimers.

Recommended Citation

Pack, Kristen Nicole, "Elucidation of Fragmentation Pathways of Nitrile-Terminated PPI Dendrimer-Metal Complexes" (2010). Theses, Dissertations and Capstones. 422.
https://mds.marshall.edu/etd/422