The [(salen)CrCl + LB] catalyst system was found to be a highly active catalyst system for the [aziridine + CO<sub>2</sub>] coupling reaction, and exhibited a marked preference for the formation of 5-substituted oxazolidinone product, especially in the absence of cocatalyst. The activity of this catalyst system is optimized by modifying...
A catalytic, multi-component coupling reaction for the synthesis of nitrogen-containing heterocycles has been developed, via the reaction of an imine, &#945;-diazoester and unsaturated coupling partner in the presence of a copper(I) or rhodium(II) transition metal catalyst with excellent diastereo-selectivities and high yields. The transition metal-catalyzed decomposition of a diazo compound...
High relaxivity contrast agents are of great importance in the advancement of magnetic resonance imaging diagnostics for use in biomaterials. Biomaterials that are implanted into the body, with the goal of repairing or regenerating lost or damaged tissue, need to be tracked noninvasively, over time. I have completed work using...
Two new strategies have been developed to accomplish direct nucleophilic acylation reactions. In the first approach, acylsilanes are added to various electrophiles using N-heterocyclic carbenes as catalysts. The second method utilizes O-silyl thiazolium carbinols as stoichiometric acyl anion precursors to afford acylated products under mild reaction conditions.
N-heterocyclic carbenes generated...
Local structure determination in amorphous and disordered systems, which are crystallographically intractable, is critical for gaining an understanding of their properties. X-ray absorption spectroscopy (XAS) is an excellent tool for local structure determination in amorphous and disordered environmental materials. Amorphous manganese oxides produced by the freshwater bacterium Leptothrix discophora SP6...
Counteranion effects on the rate and stereochemistry of propylene polymerization mediated by ion-pair complexes derived from dimethylzirconocene precatalysts activated with strongly Lewis-acidic perfluoroarylmetalloid cocatalyst/activators are shown to arise from the strength of the cation-anion interaction. This is quantified using CS-symmetric Me2C(Cp)(Flu)ZrMe2 (Cp = C5H4, &#951;5 cyclopentadienyl; Flu = C13H8, &#951;5...
In Chapter 1, a series of "constrained geometry" organoactinide complexes, (CGC)An(NMe)2 (CGC = Me2Si(h5-Me4C5)(tBuN); An = Th, 1; U, 2), prepared via efficient in situ, two-step protodeamination routes in good yields and high purity, is presented. Both 1 and 2 are quantitatively converted to the neutrally charged, solvent-free dihalides (1-Cl2,...
Understanding the nature of quantum effects in dense biological systems is of great interestto many scientists today. It seems that the question is not does quantum mechanics dictatebiological processes, but rather by how much and to what extent. A big challenge though in thisfield is how to properly test and...
This dissertation describes the relationship between the surface chemistry of colloidal semiconductor nanocrystals (quantum dots, QDs) and their optoelectronic properties, such as photoluminescence and degree of quantum confinement. We primarily focus our efforts on one particular subset of ligands known to couple strongly to the inorganic core of the QD...
Climate change may be one of the most important puzzles the world has attempted to solve and one of the greatest challenges in this area is to improve our understanding of how atmospheric aerosol particles impact climate processes. We seek to overcome this challenge by focusing on the chemistry and...