Chemistry and Biochemistry
Bayer School of Natural and Environmental Sciences
Michael Van Stipdonk
Tandem-Mass Spectrometry, Uranyl Ion, IRMPD Spectroscopy, CID
Developing a comprehensive understanding of the intrinsic reactivity of uranium-containing species remains an important goal, as it may influence future developments in areas ranging from new approaches to nuclear fuel processing to studies of the migration and fate of the element in the environment. At a more fundamental level, such studies contribute to the understanding of the role that 5-f electrons may play in chemical bonding, the so called “f-electron challenge”. Electrospray ionization (ESI) is an effective way to generate gas-phase complexes containing uranium and uranyl ions for subsequent studies of intrinsic structure and reactivity. Studies in the gas-phase are important and necessary because investigation of reactivity in the condensed phase, in a species-specific fashion, is complicated by the presence of solvent molecules and counter ions and complex equilibria between metallic species in different form.
Recent experiments have demonstrated that state-of-the art linear ion traps (LIT) can provide access to a wide range of fragmentation pathways and reactions for gas-phase uranium species, whether using collision-induced dissociation (CID) and ion-molecule reactions (IMRs), including ones that were masked in previous experiments by high partial pressures of adventitious H2O present in 3-D ion traps.
The goal was to survey the types of unimolecular (by CID) and bimolecular (IMR) reactions of precursor and product ions. The experiments outlined in this thesis were undertaken to investigate the intrinsic reactivity of uranium-containing complexes with a variety of ligands including nitrate, perchlorate, acetate, propionate, acrylate, benzoate, and combinations of different halides. However, a general limitation of mass spectrometry approaches to the study of intrinsic chemistry is that no direct structural information is produced, and determinations of structure rely heavily either on chemical intuition or theoretical calculations - understanding gas-phase reactivity requires a clearer idea of ion structure. Therefore, an addition goals was to use density functional theory (DFT) calculations, and infrared multiple-photon photodissociation (IRMPD) spectroscopy were used to identify the conformations of selected gas-phase uranyl complexes to enhance the understanding of the relationship between structure and reactivity.
Tatosian, I. (2020). Using Tandem Mass Spectrometry and IRMPD Spectroscopy to Determine the Intrinsic Reactions of Uranyl-Containing Ions (Master's thesis, Duquesne University). Retrieved from https://dsc.duq.edu/etd/1899
“Collision-induced dissociation of [UVIO2(ClO4)]+ revisited: Production of [UVIO2(Cl)]+ and subsequent hydrolysis to create [UVIO2(OH)]+ ” Tatosian, I.J., Iacovino, A.C., Van Stipdonk, M.J.; Rapid Communications in Mass Spectrometry. 29, 1416-1422 (2018).
“Influence of Background H2O on the Collision-Induced Dissociation Products Generated from [UO2NO3]+” Van Stipdonk, M.J., Iacovino, A., Tatosian, I.; Journal of American Society for Mass Spectrometry. 29, 1416-1424 (2018).
“Formation and hydrolysis of gas-phase [UO2(R)]+: R = CH3, CH2CH3, CH=CH2, and C6H5” Tatosian, I., Bubas, A., Iacovino, A., Kline, S., Metzler, L., Van Stipdonk, M.; Journal of Mass Spectrometry. 54, 780-789 (2019).
“Measurement of the asymmetric UO22+ stretching frequency for [UVIO2(F)3]- using IRMPD spectroscopy” Tatosian, I., Metzler, L., Graça, C., Bubas, A., Corcovilos, T., Martens, J., Berden, G., Oomens, J., Van Stipdonk, M.; International Journal of Mass Spectrometry. 446, (2019).