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Thermoionization And Dissociation Of Fullerenes And Endohedral Fullerenes, Rongping Deng

Doctoral Dissertations

Electron emission and unimolecular dissociation of energetically excited fullerenes and endohedral fullerenes are studied with mass spectrometry. Three experimental approaches have been developed for these studies. These are UV laser excitation time-of-flight mass spectrometry (TOF-MS), laser desorption and ionization mass spectrometry (LDI-MS), and ion-molecule collision mass spectrometry (IMC-MS).

Our first experimental effort is to investigate delayed electron emission from multiphoton excited C60 molecules. A lower limit of the probability of electron emission from multiphoton excited C60 molecules is determined to be about 2.6%. This result indicates that electron emission is not merely parasitic to dissociation.

The second experimental effort is …

Synthetic, Structural, And Stability Studies Of Metal Complexes Of Cross -Bridged Tetraamine Macrocycles, Weijun Niu

Doctoral Dissertations

Cross-bridging of tetraazamacrocyclic ligands with an ethylene unit forms a family of bicyclic tetraamine ligands originally designed and synthesized by the Weisman-Wong research group to selectively complex small metal ions such as Li+ in a cis-folded configuration. Cu(II), Ga(III), and In(III) complexes of these cross-bridged ligands have potential radiometal-based pharmaceutical applications due to their high kinetic stabilities. Cu(II) complexes of eight cross-bridged tetraazamacrocyclic ligands have been synthesized and structurally characterized. Their relative kinetic stabilities were evaluated by monitoring acid-promoted dissociation processes using UV-Vis spectroscopy. The copper complex of a dicarboxylate pendant-armed cross-bridged cyclam was the most inert, consistent with its …

Chemical Sensors Based On Swellable Molecularly Imprinted Polymer Microspheres In A Hydrogel, Wenzhe Fan

Doctoral Dissertations

A novel design of chemical sensors based on swellable molecularly imprinted polymer microspheres is presented. These sensors were successfully used to measure norephedrine and theophylline in water and in buffer at neutral pH.

A new method was developed for preparing swellable norephedrine templated poly (N-isopropylacrylamide-acrylic acid) (poly NIPA-AAc) particles by suspension polymerization in a perfluorocarbon solvent using ultrasonic emulsion technique. The particles were crosslinked with 5% of N, N'-methlene-bis-acylamide (MBA) using 20% fluorinated surfactant as a stabilizer. The resulting particles were around 6 mum in diameter. HYPAN and poly (vinyl alcohol) (PVA) hydrogels were used to make hydrogel membranes containing …

Hydrodynamic Behavior And Thermal Stability Of A Pegylated Protein: Studies With Hen Egg Lysozyme, Yatin R. Gokarn

Doctoral Dissertations

We studied the effect of covalent attachment of polyethylene glycol (PEGylation) on the hydrodynamic behavior and thermal stability of a model protein---Hen Egg Lysozyme (HEL). HEL was modified with a linear, 20-kD, PEG to produce mono (PEG1-HEL), di (PEG2-HEL), and triPEGylated (PEG3-HEL) species.

The hydrodynamic properties of HEL were altered upon PEGylation. A decrease in sedimentation (s) and diffusion (D) coefficients was observed for all three PEG-HEL molecules in comparison to HEL (1.81 s). Despite differences in molecular weights of the PEG-HEL molecules (∼34, 55 and 80 kD), their s values were very close (1.0--1.1 s). Significant hydrodynamic non-ideality was …

Thermal Rearrangements Of Linear Carbon Chains: Theoretical And Experimental Studies, John Mabry

Doctoral Dissertations

The potential energy surface of linear hydrocarbons has been extensively investigated by experiments and the use of molecular modeling. Linear C4 structures have demonstrated the potential to scramble their inner carbon atoms leading to the formation of novel strained intermediates.

Long-range carbon atom topomerization in a 1,3-diyne has been demonstrated for the first time. 1-Phenyl-4-p-tolyl-1,3-butadiene, 13C enriched at C-1, was synthesized and subjected to flash vacuum pyrolysis. Under high temperature and at low pressure, this resulted in nearly complete 13C label equilibration among all of the sp hybridized carbons, as seen by NMR analysis. It has been proposed that 1,3-diynes …