Structural studies using chemical ionisation ion trap mass spectrometry

Williamson, BL, 1996. Structural studies using chemical ionisation ion trap mass spectrometry. PhD, Nottingham Trent University.

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Abstract

Chemical ionisation (CI) studies have been carried out using quadrupole ion trap mass spectrometry. The reactions of benzoyl cations, of the type [C6X5CO]+ (where X= H, F, 4-Me, 4- But), with compounds containing hydroxy, double bond and amine functionality have been investigated. The formation of [M+C6X5CO]+, [M-H]+ [M-OH]+ products with hydroxyl compounds is determined by the hydroxy group environment in agreement with the known thermochemistry of these ions and a molecular modelling study of the electrophilic addition. The formation of [M+C6H5CO]+, [M-NH2]+ and protonated benzamide ions with compounds containing the amino functionality is determined by the environment of the amine group. These mass selected reagent ions show limited reactivity towards other compounds. Substitution of the benzoyl cation with fluorine or a methyl group modifies the electrophilic character of the benzoyl cation, allowing the selectivity of its reactions to be controlled. The selectivity of the chemical ionisation reactions of the benzoyl ions is demonstrated by their reactions with analytes of pharmaceutical interest containing hydroxy, double bond and amine functionality.

Negative Cl reactions of [OH]- and [C6H5CO]- have also been investigated in the ion trap. The reactions of the benzoyl anion, [C6H5CO]-, formed as the [M-H]- ion from the [OH]- chemical ionisation reaction with benzaldehyde inside the ion trap are described. This ion reacted selectively as a nucleophile towards the carbonyl functional group of the aldehyde and ketone compounds investigated and may have potential as a selective chemical ionisation reagent for these classes of compounds.

The formation of gas-phase non-covalent inclusion complexes of crown ethers with protonated amines is reported. The effect of varying the structure of protonated amines of the type [R-NH3]+ (where R= C3H7, C6H5C2H4, O2NC6H4C2H4 or C6H5CH2C(H)COOH) on the interaction with the crown ethers 18-crown-6, benzo-18-crown-6 and (s)-phenyl-18-crown-6 to form non-covalent inclusion complexes has also been studied. This structure variation has a strong effect on the stability of the non-covalent inclusion complexes formed with the crown ethers. Ligand exchange and competition experiments have been used to assign the relative affinities of host-guest combinations.

Item Type:	Thesis
Creators:	Williamson, B.L.
Date:	1996
ISBN:	9781369323719
Identifiers:	Number Type PQ10290122 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	02 Oct 2020 13:01
Last Modified:	03 Oct 2023 15:34
URI:	https://irep.ntu.ac.uk/id/eprint/41117

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