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The Mechanisms of Methane C–H Activation and Oxy-insertion Via Small Transition Metal Complexes: a DFT Computational Investigation (open access)

The Mechanisms of Methane C–H Activation and Oxy-insertion Via Small Transition Metal Complexes: a DFT Computational Investigation

Our country continues to demand clean renewable energy to meet the growing energy needs of our time. Thus, natural gas, which is 87% by volume of methane, has become a hot topic of discussion because it is a clean burning fuel. However, the transportation of methane is not easy because it is a gas at standard temperature and pressure. The usage of transition metals for the conversion of small organic species like methane into a liquid has been a longstanding practice in stoichiometric chemistry. Nonetheless, the current two-step process takes place at a high temperature and pressure for the conversion of methane and steam to methanol via CO + H2 (syngas). The direct oxidation of methane (CH4) into methanol (CH3OH) via homogeneous catalysis is of interest if the system can operate at standard pressure and a temperature less than 250 C. Methane is an inert gas due to the high C-H bond dissociation energy (BDE) of 105 kcal/mol. This dissertation discusses a series of computational investigations of oxy-insertion pathways to understand the essential chemistry behind the functionalization of methane via the use of homogeneous transition metal catalysis. The methane to methanol (MTM) catalytic cycle is made up of two key …
Date: May 2014
Creator: Prince, Bruce M.
System: The UNT Digital Library
Targeted and Metal-loaded Polymeric Nanoparticles As Potential Cancer Therapeutics (open access)

Targeted and Metal-loaded Polymeric Nanoparticles As Potential Cancer Therapeutics

Polymeric nanoparticles were designed, synthesized, and loaded with metal ions to explore the therapeutic potential for transition metals other than platinum found in cisplatin. Nanoparticles were synthesized to show the potential for polymer based vectors. Metal loading and release were characterized via Inductively Coupled Plasma Mass Spectrometry (ICP MS), Energy Dispersive X-Ray Spectroscopy (EDX), X-Ray Photoelectron Spectroscopy (XPS), and Elemental Analysis. Targeting was attempted with the expectation of observed increased particle uptake by cancer cells with flow cytometry and fluorescence microscopy. Results demonstrated that a variety of metals could be loaded to the nano-sized carriers in an aqueous environment, and that the release was pH-dependent. Expected increased targeting was inconsistent. The toxicity of these particles was measured in cancer cells where significant toxicity was observed in vitro via dosing of high copper-loaded nanoparticles and slight toxicity was observed in ruthenium-loaded nanoparticles. No significant toxicity was observed in cells dosed with metal-free nanoparticles. Future research will focus on ruthenium loaded polymeric nanoparticles with different targeting ligands dosed to different cell lines for the aim of increased uptake and decreased cancer cell viability.
Date: May 2014
Creator: Harris, Alesha N.
System: The UNT Digital Library