Investigation Of The Molecular Structure Characterzation Of Organic Compounds By Ion-Trap Mass Spectrometry

With the development of ion-trap mass spectrometry (IT-MS), it has been extensively applied to the wide area of analytical chemistry. The advantages in many applications are based on the sensitive, accurate and fast characteristics of this technology. At the same times, it could offer much information about the structure characterization of analytes. In the present thesis, the fragmentation mechanism and structure characterization of three different organic compounds, including quinazoliones derivatives, transition metal complexes of triarylamines and 7-substituted benzopyrano[3,2-c]chromene-6,8-diones derivatives were studied by IT-MS.First, the energy resolved mass spectrometry breakdown curves for monomers and mixtures of 4(3H)-quinazolinone and 4-Cl-quinazoline isomers have been investigated by electron ionization tandem mass spectrometry (EI-MS/MS), respectively. The results showed that the breakdown curves for the isomeric compounds were related closely to the position of substituent displaced on isomers skeleton. Based on the obvious difference of their breakdown curves, the monomer or mixture of 4(3H)-quinazolinone and 4-Cl-quinazoline isomers can be identified and discriminated conveniently.Second, the complexation of the triarylamines derivatives with transition metal ions (Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) in the gas phase has been studied by electrospray ionization ion trap mass spectrometry (ESI-IT-MS) in positive ionization mode. The results showed that during the ESI-MS process, the ligands BTBP-FPA, BFP-FPA and BMP-FPA mainly formed singly charged complexes [M(L)2]+ due to the reduction reactions from Cu²⁺, Ni²⁺ and Co²⁺ to Cu⁺, Ni⁺ and Co⁺, respectively. However, for ligands BDTA-PA and BDPA-BPA, only the Cu complexes were observed. In addition, collision-induced dissociation (CID) was employed to study these complexes structures and evaluate the relative stabilities of these complexes. Furthermore, the important information regarding the metal coordination sites about transition metal-triarylamine complexes were also obtained in the CID experiments.At last, the fragmentation mechanisms of 7-substituted benzopyrano[3,2-c]chromene-6,8-diones derivatives were studied by electrospray ionization ion-trap mass spectrometry. Three different formation of the protonated ions [M+H]+, the sodium adduct ions [M+Na]+ and the potassium adduct ions [M+K]+ in the positive-ion mode were observed. For compounds 1, 10, 17, 18, 19 and 22, only the formation of [M+Na]+ ions were observed. Their molecular ions [M+Na]+ were very stable and no fragment ion was observed in CID process. On the other hand, the [M+H]+ ions of other compounds were favored to undergoing enol rearrangement, then the fragmental ions at m/z 295 or m/z 267 were produced by the netural loss of 7-substituted functional group. Moreover, attributed to the substituents on C-10 postiton, the fragmentation mechanism of benzopyrano[3,2-c]chromene-6,8-diones and 10,10-dimethyl-benzopyrano[3,2-c]chromene-6,8-diones were obviously different.