Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1995. / by Zygmunt J. Jakubek. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 139-149). / The Coulomb correlations between photoexcited charged particles in materials such as photosynthetic complexes, conjugated polymer systems, J-aggregates, and bulk or nanostructured semiconductors produce a hierarchy of collective electronic excitations (i.e. excitons, biexcitons, etc.) which may be harnessed for applications in quantum optics, light-harvesting, or quantum information technologies. These excitations represent correlations among successively greater numbers of electrons and holes, and their associated multiple-quantum coherences could reveal detailed information about complex many-body interactions and dynamics. However, unlike single-quantum coherences involving excitons, multiple-quantum coherences do not radiate and they have largely eluded direct observation and characterization. In this work, I present a novel optical technique, two-quantum two-dimensional Fourier transform optical spectroscopy, which allows direct observation of the dynamics of multiple-exciton states that reflect the correlations of their constituent electrons and holes. The approach is based on closely analogous methods in nuclear magnetic resonance, in which multiple phase-coherent fields are used to drive successive transitions such that multiple-quantum coherences can be accessed and probed. A spatiotemporal femtosecond pulse shaping technique has been used to overcome the challenge of control over multiple, noncollinear phase-coherent optical Fields in the experimental geometries that are used to isolate selected signal contributions through wavevector matching. / (cont.) Results from a GaAs quantum well system reveal distinct coherences of biexcitons that are formed from two identical excitons or from two excitons whose holes are in di®erent spin sublevels ("heavy-hole" and "light-hole" excitons). The biexciton binding energies and dephasing dynamics are determined, and changes in the dephasing rates as a function of the excitation density are observed, revealing still higher-order correlations due to exciton-biexciton interactions. Two-quantum coherences due to four-particle correlations that do not involve bound biexciton states but that in°uence the exciton properties are also observed and characterized. I also present one-quantum two-dimensional Fourier transform optical spectroscopy measurements which show that the higher-order correlations isolated by two-quantum techniques are highly convolved with two-particle correlations in the conventional one-quantum measurements. / by Katherine Walowicz Stone. / Ph.D.

Thesis (B.S.) Massachusetts Institute of Technology. Dept. of Chemistry, 1952. / MIT copy bound with: An infrared study of acetoacetic ester / John B. Schutt. 1952. / by Bruno Martino Vittimberga. / B.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1937. / Vita. / Includes bibliographical references (leaves [53]-[54]). / by Robert Burns Woodward. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999. / Includes bibliographical references (leaves 110-116). / by Thomas James Boyd. / Ph.D.

Thesis: Ph. D. in Biological Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2014. / Cataloged from PDF version of thesis. Vita. / Includes bibliographical references. / Ralstonia eutropha, a Gram-negative proteobacterium, is capable of utilizing a plethora of simple and complex carbon sources derived from common waste streams. When experiencing nutrient stress in the presence of high carbons, R. eutropha can store carbon and energy in the form of polyhydroxyalkanoates (PHAs), a biodegradable and biocompatible plastic. In this thesis, the native carbon storage system was genetically disabled and the carbons redirected to produce biofuels. Key enzymes involved in R. eutropha CO₂, oil, and branched-chain amino acid metabolism were evaluated for the production of biofuels and bioplastics. R. eutropha valine biosynthesis pathway was modified, so its intermediate 2- ketoisovalerate can be converted to isobutanol, a drop-in biofuel that can directly substitute for fossil-based fuels and be employed within the current transportation infrastructure. Challenges facing large production of isobutanol include the tightly regulated biosynthetic pathway and product toxicity to the cells. Modification of both the pathway enzyme for reduced-feedback inhibition, in addition to genotypic adaptation to exogenous isobutanol stress produced insights that will allow for further improvements on isobutanol production. Furthermore, strains of R. eutropha were also engineered to produce isopropanol, another biofuel. Growth on carbon dioxide requires carefully balanced intercellular pH and ion transport. Four R. eutropha carbonic anhydrases were identified to play individual and non-complementary roles in CO₂ metabolism. An extracellular lipase and its chaperone were identified and characterized in R. eutropha. This lipase is crucial for growth on plant oil and when overexpressed, not only reduced the growth lag phase, but also eliminated the use of supplemental surfactants. Production of PHAs was achieved by using palm oil, one of the world's most abundant plant oils, as well as vinasse, a byproduct of ethanol fermentation. Metabolic versatility and genetic tractability combined with its ability to store a variety of carbons make R. eutropha an excellent platform organism for the production of value-added compounds. Demonstrated in this thesis are the production of biofuels and bioplastics from fructose, CO₂, oils, and mixed-organic acids. / by Jingnan Lu. / Ph. D. in Biological Chemistry

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1988. / Vita. / Bibliography: leaves v.2, 346-356. / by Richard S. Johnson. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005. / Vita. / Includes bibliographical references. / A general amination strategy for the N-alkynylation of carbamates, sulfonamides, and chiral oxazolidinones and imidazolidinones is described. A variety of substituted ynamides are available by deprotonation of amide derivatives with KHMDS followed by reaction with CuI and an alkynyl halide. Ynamides react with conjugated enynes in intramolecular [4 + 2] cycloaddition to afford substituted indolines that undergo oxidation with o-chloranil to furnish the corresponding indoles. The cycloaddition substrates are easily assembled from derivatives of 3-butynylamine by Sonogashira coupling with alkenyl halides followed by copper-catalyzed N-alkynylation with acetylenic bromides. Diynamides participate as particularly reactive 2[pi] components in the cycloaddition, providing access to indolines with carbon substituents at the C-7 position. Enynamides serve as 4[pi] components in a complementary version of the cycloaddition strategy which provides access to indoles and indolines substituted with substituents at C-4. These enyne cycloadditions take place upon heating the substrates at 110-210⁰C in toluene or 2,2,2- trifluoroethanol and in some cases can be achieved at 0⁰C to room temperature in the presence of Lewis acids such as Me₂A1C1. / (cont.) We have developed a "green" strategy to effect acyl-Pictet-Spengler reactions in multiphasic scCO₂/CO₂-expanded liquid media. These cyclizations of iminium ions provide tetrahydroisoquinolines and tetrahydro-[beta]-carbolines that have valuable medicinal properties. Critical to the success of these reactions is the in situ conversion of [beta]-arylethylamine reactants to c;arbamate derivatives by reaction with carbon dioxide and dialkyl carbonates. The application of this general strategy for utilizing amines in other carbon-nitrogen bond-forming reactions in environmentally-friendly media is under investigation. / by Joshua Ross Dunetz. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008. / Vita. / Includes bibliographical references. / In Part I, nickel-catalyzed asymmetric carbon-carbon bond-forming reactions are described. A nickel/Pybox system effectively catalyzes regio- and enantioselective cross-couplings between racemic secondary allylic chlorides and readily available alkylzinc halides. This method is applied to generate two stereo centers in a formal total synthesis of fluvirucinine A1. In Part II, the use of planar-chiral compounds as ligands or catalysts in organic synthesis is described. A C2-symmetric planar-chiral bipyridine is an efficient ligand for copper-catalyzed asymmetric [4+1]-cycloadditions between enones and diazoacetates to form 2,3-dihydrofurans. The highly substituted dihydrofurans are not only obtained in good stereoselectivity but also readily converted to other useful molecules. This method is applied to the first catalytic enantioselective synthesis of a deoxy-C-nucleoside. The synthesis of new C2-symmetric planar-chiral catalysts is described. The diastereoslective functionalization of ferrocene using a chiral directing group enables the formation of a number of amines in enantiopure form. These catalysts are tested as several asymmetric catalysts. / by Sunghee Son. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1939. / Vita. / Includes bibliographical references (leaves 74-75). / by Bernard Vonnegut. / Ph.D.