Abstract not available

This thesis reports the studies on the reaction of 1-azabutadienes with PhCH2Re(CO)5 to prepare the cyclometallated azabutadiene tetracarbonyl compounds. Three 1-azabutadienes with different reactivity on the N and C-1 carbons were prepared and their reactions with PhCH2Re(CO)5 were investigated. All the reactions gave a mixture of the cyclorheniated azabutadienes and the isomers of the substituted derivatives formed by substitution by a second azabutadiene. The substituted derivatives as the mixture were always the main products of the reactions and were obtained in good-to-excellent yield even under modified conditions intended to optimise the yield of the cyclorheniated azabutadienes. The yield could not be improved beyond 30 %. Isomerisation of the azabutadiene about the N=C bond provided very rare cis-azabutadiene metal complexes. NMR studies on the mixture of the two isomers and suggested that the product ratio depended on the molar ratio of PhCH2Re(CO)5 in the reaction mixtures. The reactions gave the Re analogues of the products obtained in the corresponding Mn reactions. All the compounds were characterised spectroscopically as well as by microanalysis and examples of all three types were structurally determined by X-ray crystallography. The reactions of the substituted derivative as the mixture of the two isomers with unsaturated molecules including phenyl acetylene, p-methoxyphenyl isocyanide, and phenyl isocyanate and methyl acrylate were investigated.

Doctor of Philosophy(PhD) / Particle formation in RAFT-mediated emulsion polymerization has been studied using reaction calorimetry. By measuring the heat flow during controlled feed ab-initio emulsion polymerization in the presence of amphipathic RAFT agents, particle formation by self-assembly of these species could be observed. Two different monomer systems, i.e. styrene and n-butyl acrylate, and various degrees of hydrophobicity of the initial macro-RAFT agents have been studied and compared. The different macro-RAFT agents were synthesized by first forming a hydrophilic block of poly(acrylic acid) that would later on act as the electrosteric stabilizing group for the particles. Subsequently, different lengths of hydrophobic blocks were grown at the reactive end of the poly(acrylic acid) hydrophilic block via the RAFT-mediated controlled radical polymerization, either comprised of n-butyl acrylate or styrene. Two processes govern particle formation: adsorption of macro-RAFT agents onto growing particles and formation of new particles by initiation of micellar aggregates or by homogeneous nucleation. Competition between these processes could be observed when monomers with a relatively high (n-butyl acrylate) or low (styrene) propagation rate coefficient were used. A model describing particle formation has been developed and the results of model calculations are compared with experimental observations. Preliminary modeling results based on a set of reasonable physico-chemical parameters already showed good agreement with the experimental results. Most parameters used have been verified experimentally. The development of the molecular weight distribution of the macro-RAFT agents has been analyzed by different techniques. Quantification of the particle formation process by analytical techniques was difficult, but qualitative insights into the fundamental steps governing the nucleation process have been obtained. The amount of macro-RAFT agents initially involved in particle formation could be determined from the increase of molecular weight. The particle size distribution has been measured by capillary hydrodynamic fractionation, transmission electron microscopy and dynamic light scattering. From the data obtained from these particle-sizing techniques, the number of particles during the reaction could be monitored, leading to an accurate estimate for the particle formation time. Upon implementation of the experimental data obtained for the surface active macro-RAFT systems, the model demonstrated to be very sensitive towards the “headgroup” area of the macro-RAFT species. Three nucleation cases based on the initial surface activity of the macro-RAFT species in the aqueous phase are proposed to explain the deviations from the assumptions of the nucleation model. Even though the macro-RAFT species have a narrow molecular weight distribution, they are nevertheless made up of a distribution of block lengths of polystyrene upon a distribution of block lengths of poly(acrylic acid). The resulting differences in initial surface activity are the most probable reason for the observed differences between model calculations and experimental results for the nucleation time and particle size distribution of the final latex product. With the procedure described above, latexes have been synthesized without using conventional surfactants and the mechanisms involved in the particle formation for these systems have been elucidated. The results of this work enable production of latex systems with well defined molecular mass distributions and narrow particle size distributions. Furthermore, the technique based on the application of amphipathic RAFT agents is promising for the production of complex polymeric materials in emulsion polymerization on a technical scale.

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaf 30).

R.B. Lawrance [and] M.W.P. Strandberg. / "October 3, 1950." / Bibliography: p. 16. / Army Signal Corps Contract No. W36-039-sc-32037 Project No. 102B. Dept. of the Army Project No. 3-99-10-022.

Molecular dynamic simulation is utilized to investigate the adsorption mechanism of water molecules surrounding Au nanoparticle of different sizes. We selected 13, 55, 147 atoms icosahedral gold nanopartilce in our model and their diameter are 7.92Å, 13.2Å, 18.5Å, respectively. We calculated density profile of water molecules and found that there were two adsorption layers out of the surface of gold nanoparticles. We also calculated average number of hydrogen bonds per water . It is higer in the adsorption layer than in bulk water region and we found that the direction of hydrogen bonds are numerously parallel with gold surface in the adsorption layer. We also claculated orientational order parameter for water molecules and explore the difference of the tetrahedral structure of the water molecules between the adsorption layer and bulk water region. Besides, we compared of cases of different gold sizes.

Ten gaseous transient metal-containing molecules have been synthesized and studied by high resolution spectroscopy. Transient molecules are molecules with a short lifetime, and they play an important role in chemistry because they are reaction intermediates. One of the difficulties faced in studying transient molecules is their typically low concentrations under laboratory conditions. Three types of sources were used to generate these molecules: 1) an emission source that combines a high temperature furnace with an electrical discharge was used to generate SbH, SbD, TeH, TeD, CdH2, CdD2, HZnCl and BeF2; 2) a King furnace (carbon tube furnace) was used to synthesize CoS; 3) a Broida-type oven (metal flow reactor) was used to generate SrOD. Two spectroscopic techniques were employed to study these molecules: 1) Fourier transform infrared emission spectroscopy was used to study SbH, SbD, TeH, TeD, CdH2, CdD2, HZnCl, BeF2, and CoS. 2) Laser-induced fluorescence spectroscopy was employed to study SrOD. One or two lasers were used to excite the SrOD molecules from the ground state to excited electronic states and then these SrOD molecules relaxed back to the ground state by emitting fluorescence, which was detected by a photomultiplier tube. Significantly-improved spectroscopic constants have been obtained for SbH, SbD, TeH and TeD. For SbH and SbD, the infrared X 3– vibration-rotation bands and the near infrared b 1+ – X 3– transition were observed and rotationally analyzed, and a Hund’s case (a) fit was performed for each of the four observed SbH isotopologues. For TeH and TeD, the X 23/2 vibration-rotation bands and the near infrared X 21/2– X 23/2 transition have been observed and rotationally analyzed, and Hund’s case (a) and case (c) fits were performed for each of the ten observed TeH isotopologues. New spectroscopic constants were obtained for HZnCl, CdH2 and CdD2. These three molecules have been successfully generated in the gas phase for the first time. The fundamental band and one hot band were obtained for the H–Zn stretching mode (1) and for the antisymmetric stretching mode (3) of CdH2 and CdD2. A least-squares fit was performed for each of the four observed HZnCl isotopologues and the twelve observed CdH2 isotopologues For the first time, a complete set of molecular constants for all three vibrational frequencies was experimentally determined for BeF2. Thirteen new hot bands were rotationally analyzed and the 1, 2, and3 vibrational frequencies were directly determined by fitting nineteen bands together. The traditional equilibrium vibrational and rotational constants were obtained for BeF2 by simultaneously fitting the observed vibrational term values and B rotational constants. New spectroscopic constants were obtained for two electronic states of CoS and SrOD, respectively. The A 4i – X 4i and B 4i – X 4i transitions of CoS and the and transitions of SrOD were observed for the first time. Hund’s case (c) fits were performed for the CoS transitions and Hund’s case (a) fits were performed for the SrOD transitions.

Ten gaseous transient metal-containing molecules have been synthesized and studied by high resolution spectroscopy. Transient molecules are molecules with a short lifetime, and they play an important role in chemistry because they are reaction intermediates. One of the difficulties faced in studying transient molecules is their typically low concentrations under laboratory conditions. Three types of sources were used to generate these molecules: 1) an emission source that combines a high temperature furnace with an electrical discharge was used to generate SbH, SbD, TeH, TeD, CdH2, CdD2, HZnCl and BeF2; 2) a King furnace (carbon tube furnace) was used to synthesize CoS; 3) a Broida-type oven (metal flow reactor) was used to generate SrOD. Two spectroscopic techniques were employed to study these molecules: 1) Fourier transform infrared emission spectroscopy was used to study SbH, SbD, TeH, TeD, CdH2, CdD2, HZnCl, BeF2, and CoS. 2) Laser-induced fluorescence spectroscopy was employed to study SrOD. One or two lasers were used to excite the SrOD molecules from the ground state to excited electronic states and then these SrOD molecules relaxed back to the ground state by emitting fluorescence, which was detected by a photomultiplier tube. Significantly-improved spectroscopic constants have been obtained for SbH, SbD, TeH and TeD. For SbH and SbD, the infrared X 3– vibration-rotation bands and the near infrared b 1+ – X 3– transition were observed and rotationally analyzed, and a Hund’s case (a) fit was performed for each of the four observed SbH isotopologues. For TeH and TeD, the X 23/2 vibration-rotation bands and the near infrared X 21/2– X 23/2 transition have been observed and rotationally analyzed, and Hund’s case (a) and case (c) fits were performed for each of the ten observed TeH isotopologues. New spectroscopic constants were obtained for HZnCl, CdH2 and CdD2. These three molecules have been successfully generated in the gas phase for the first time. The fundamental band and one hot band were obtained for the H–Zn stretching mode (1) and for the antisymmetric stretching mode (3) of CdH2 and CdD2. A least-squares fit was performed for each of the four observed HZnCl isotopologues and the twelve observed CdH2 isotopologues For the first time, a complete set of molecular constants for all three vibrational frequencies was experimentally determined for BeF2. Thirteen new hot bands were rotationally analyzed and the 1, 2, and3 vibrational frequencies were directly determined by fitting nineteen bands together. The traditional equilibrium vibrational and rotational constants were obtained for BeF2 by simultaneously fitting the observed vibrational term values and B rotational constants. New spectroscopic constants were obtained for two electronic states of CoS and SrOD, respectively. The A 4i – X 4i and B 4i – X 4i transitions of CoS and the and transitions of SrOD were observed for the first time. Hund’s case (c) fits were performed for the CoS transitions and Hund’s case (a) fits were performed for the SrOD transitions.

In this study, sharp/gradual converging-diverging microchannels with contraction/ expansion ratio of 4:1/1:4 was designed to generate elongational flow with uniform velocity in the centerline. The £f-DNA stained with YOYO-1 was observed in the flow. MPIV was built to measure the velocity distribution and local strain rate was estimated by MPIV measurements. The deformation and conformation of individual DNA molecules in the flow was visualized with confocal laser scanning microscopy (CLSM). The goal of the present work was to develop a method for stretching DNA molecules, in order to perform analysis of coil-stretch transition of DNA. By measuring dynamic properties and relaxation time of DNA molecules stretched by pressure driven at various flow rate and viscosity, we have shown how one could investigate the influence of hydrodynamic interactions in the case of stretching of DNA molecules.

In recent years, the characteristic of Nano fluid channel has important contribute in bio-technology and nano-machine. Gold atoms in all materials have significant effects on human bodies, which have attracted considerable academic interests when applied to biotechnology. Especially the Au nanotubes has combine an excellent bio-compatible not only using in chemical analyzed and chemical inspect, but also has function on transport fluid molecule in micro channel. This study utilizes molecular dynamics to the behavior of water molecules inside Au nanotubes. We used the potential of Spohr, F3C and Tight-binding in different water density and temperature to investigate the adsorption mechanism and dynamic behavior of water molecules inside Au nanotubes. We discuss the numbers of absorbed water molecule near the inner tube wall all achieve to saturation at three different densities, temperature and size of Au nanotubes. This work we compared water density, the percentage profiles of hydrogen bond, orientational order and flux for water molecules inside the Au nanotubes.