Silicon incorporation into Ge1-ySny yields a new class of Ge1-x-ySixSny (y>x) ternary alloys using reactions between Ge3H8, Si4H10, and SnD4. These materials contain small amounts of Si (x=0.05-0.08) and Sn contents of y=0.1-0.15. Photoluminescence studies indicate an intensity enhancement relative to materials with lower Sn contents (y=0.05-0.09). These materials may serve as thermally robust alternatives to Ge1-ySny for mid-infrared (IR) optoelectronic applications.
An extension of the above work is the discovery of a new class of Ge-like Group III-V-IV hybrids with compositions Ga(As1–xPx)Ge3 (x=0.01-0.90) and (GaP)yGe5–2y related to Ge1-x-ySixSny in structure and properties. These materials are prepared by chemical vapor deposition of reactive Ga-hydrides with P(GeH3)3 and As(GeH3)3 custom precursors as the sources of P, As, and Ge incorporating isolated GaAs and GaP donor-acceptor pairs into diamond-like Ge-based structures. Photoluminescence studies reveal bandgaps in the near-IR and large bowing of the optical behavior relative to linear interpolation of the III-V and Ge end members. Similar materials in the Al-Sb-B-P system are also prepared and characterized. The common theme of the above topics is the design and fabrication of new optoelectronic materials that can be fully compatible with Si-based technologies for expanding the optoelectronic capabilities of Ge into the mid-IR and beyond through compositional tuning of the diamond lattice.
FRDA is a progressive neurodegenerative disease caused by insufficient expression of frataxin (FXN). FXN is instrumental in the assembly of iron-sulfur clusters, which in turn are critical for the functioning of the ETC enzyme complexes. Therapeutic agents which, in addition to being antioxidants also increase FXN, can be good drugs to counter FRDA. In Chapter 2, the synthesis of phenothiazine analogues are described. Moreover, their efficacy as antioxidants and their ability to increase FXN are described. Finally, the synthesis of a reduced salt form of one analogue and its ability to cross the blood brain barrier (BBB) in mouse models of the disease is also described.
In Chapter 3, to discover potent neuroprotective drugs, a pair of regioisomeric benzoquinone analogues has been synthesized. The compounds were tested for their efficacy as antioxidants. Additionally, two pyrimidinol based redox cores were analyzed electrochemically to enable a better understanding of the mechanism of action of the multifunctional radical quencher (MRQ) class of antioxidants.
Post-consumer plastic and polymer waste accumulation in recent years continues to become more of a problem. One of the common polymers that has become ubiquitous to modern life is polyethylene terephthalate, a polymer that makes up 6.2% of all polymers produced and only 39% of which is recycled in the US annually.1,5 In this study a new catalyst was for the methanolysis of PET and compared to a common organic base, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), that has been used in academia and industry for the depolymerization of PET. In this study it was concluded that yttrium (III) acetylacetonate hydrate was a more active catalyst for the methanolysis of PET at 120 °C in comparison to TBD. It was also determined that there is no co-catalytic effect between yttrium (III) acetylacetonate hydrate and TBD when used in combination. The use of manganese (II) acetate tetrahydrate was also explored as a potential catalyst and was found to shown significant reactivity. However, it was concluded that the optimal conditions for PET methanolysis had not been reached and that further research into reaction times as well as co-solvents needs to be conducted. The synthesis of a novel o-phenylenediamine ligand functionalized with a labile phosphine substituent was also explored with the end goal of metalation and implementation in the methanolysis of PET. It has been assumed through nuclear magnetic resonance spectroscopy (NMR) characterization that the N,N’-(1,2-phenylenediamine)bis[3-(diphenylphosphanyl)-propanamide]-borane precursor was successfully synthesized and isolated. The subsequent deprotection of the N,N’-(1,2-phenylenediamine)bis[3-(diphenylphosphanyl)-propanamide]-borane complex was performed but has not been fully characterized. The 31P NMR does indicate a fully deprotected tertiary organophosphine. Through this work a detailed procedure for the ligand precursor has been laid out and developed so that the synthesis may now be scaled up, further characterized, metalated, and used to support catalysis.