Physical Sciences and Mathematics Commons^™

Pressure Tuning Of Energy Storage Materials Probed By In-Situ Vibrational Spectroscopy And Synchrotron Radiation, Pan Wang

Electronic Thesis and Dissertation Repository

Clean and renewable energy has drawn much attention recently due to the increasing demand for more energy and environmental issues. New materials have been developed and the improved performance of such materials have been achieved in the past decades. It has been proved that application of external high pressure can significantly tune the structure of materials. Consequently, the properties of the materials could also be modified. Therefore, in this thesis, we focused on the high-pressure studies of two classes of energy storage materials, hydrogen storage materials and solar cell materials. Ammonia borane (AB) has been extensively investigated as an excellent …

Exploring The Chemistry Of Asymmetric Phosphines & Phosphinidene Sulfides, Taylor E. Pritchard

Electronic Thesis and Dissertation Repository

The field of low-coordinate main group chemistry has seen huge development in the last 30 years, with novel compounds that demonstrate unique structures and reactivity. Isolation of these species has relied on thoughtfully designed substituents normally containing substructure steric bulk. The area of phosphinidene chalcogenide isolation and transfer remains poorly understood by comparison. In this context, the major focus of thesis was on the development of a room-temperature method for the transfer of RP=S moieties with and without sterically demanding substituents. The preparation and complete characterization of new asymmetric phosphines with m-terphenyl ligands was also reported. In Chapter 2, …

Design, Synthesis, And Oxidation Reactivity Of Palladacyclic Complexes Containing N-Donor Ligands, Ava Behnia

Electronic Thesis and Dissertation Repository

This thesis describes the synthesis and reactivity of complexes containing the cycloneophyl-Pd(II) group, PdCH₂CMe₂C₆H₄, in combination with N-donor ligands. These compounds contain both alkyl- and arylpalladium bonds and the selectivity of bond cleavage in reactions with oxidants and protic reagents is studied, often involving oxidative addition and reductive elimination reaction sequences.

The diimine ligand in [Pd(CH₂CMe₂C₆H₄)(MesN=CH-CH=NMes)] does not support formation of stable palladium(IV) complexes, but reactions with Br₂ or I₂ lead to reductive elimination by C-C bond formation of 1,1-dimethylcyclobutabenzene while …

Computational And Spectroscopic Studies In The Design Of Tetrapyrrole Dyes For Dye-Sensitized Solar Cells, Angel (Qi Wen) Zhang

Electronic Thesis and Dissertation Repository

Cyclic tetrapyrroles, like porphyrins, phthalocyanines, and chlorins, are of great interest for dye-sensitized solar cell (DSSC) applications due to their highly versatile structure, tunable π based spectroscopic and electrochemical properties, and excellent stabilities. As well, they have a structural analogy with chlorophyll, a natural photosensitizer. Chlorophylls exhibit a red and intense lowest energy absorption band that is one of the ideal properties of a dye for application in DSSCs. However, because chlorophylls are unstable, it is necessary to design similar but more stable tetrapyrroles with these ideal properties. The relationship between chlorophyll’s geometric structure and spectral properties were first explored …

Coinage Metal Chalcogenide Clusters With N-Heterocyclic Carbene Ancillary Ligands, Alex Polgar

Electronic Thesis and Dissertation Repository

This thesis describes the synthesis and characterization of homo- and heterometallic group 11 – group 16 clusters with N-heterocyclic carbene (NHC) ligands. The clusters were prepared from reactive group 11 trimethylsilylchalcogenolate reagents (NHC-M-ESiMe3; M = Cu, Au; E = S, Se, Te) by silane deprotection reactions with phosphine- or phosphite-solubilized group 11 acetates (R3P-M-OAc; M = Cu, Ag, Au). Clusters were characterized by combustion analysis and spectroscopic methods in solution and the solid state. The clusters were phosphorescent at low temperatures with emission energies that depend on the metal/chalcogen composition, ancillary NHC ligand, cluster geometry and nuclearity, and local environment. …

Exploring The Synthesis, Structure, And Reactivity Of Phosphorus-Chalcogen Heterocycles, Cameron Graham

Electronic Thesis and Dissertation Repository

In recent years, the field of low-coordinate main group chemistry has seen significant research interest due to their unique structures and unprecedented reactivity. Conversely, the area of phosphinidene chalcogenides, a low-coordinate phosphorus and chalcogen species, have yet to be thoroughly explored. In this context, this dissertation describes the synthesis of a number of phosphorus-chalcogen heterocycles that can be degraded to provide stoichiometric access to low-coordinate phosphorus species. The ability for successful P-Ch transfer relies on using a bulky m-terphenyl group at phosphorus that provides enough steric bulk to kinetically stabilize the phosphorus centre, but also accommodating enough to allow …

The Addition Of Alkynes To Low-Valent Silicon Compounds: A Mechanistic Study, Andrew T. Henry

Electronic Thesis and Dissertation Repository

The mechanism for the addition of alkynes to low-valent silicon compounds was investigated in this thesis using a cyclopropyl alkyne mechanistic probe (1.31). The addition of alkyne 1.31 to the asymmetrically-substituted disilene 1.37 was investigated. The structures of the products obtained indicate the reaction proceeds through a stepwise mechanism with a biradical intermediate and the dipole moment of the disilene bond was not sufficient to alter the reaction mechanism.

The addition of alkyne 1.31 to the NHC-stabilized silylene 1.38 was also investigated. The structure of the product formed in the reaction lead to two conclusions: that silylene 1.38 …

Developing Structure-Activity-Relationships For Metal-Ligand-Cooperative (Mlc) Complexes Using Pr2nr′2 Ligands, James M. Stubbs

Electronic Thesis and Dissertation Repository

Exploring efficient and environmentally-friendly routes to synthesize molecules is critical for the pharmaceutical and fine chemical industries. One method is to study current catalytic methods to increase selectivity and performance for challenging reactions. Inclusion of an intramolecular acid/base site on the ligand manifold of an organometallic complex has allowed for new mechanistic pathways and enhanced reactivity. This thesis delves into understanding organometallic complexes in catalysis by systematic tuning the ligand properties. Synthesis of P^R₂N^R′₂ ligands was performed to enable the systematic tuning as R and R′ alter the electronic and steric properties of the primary …