Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1996. / Vita. / Includes bibliographical references (leaves 135-151). / by Patrick P. Zarrinkar. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999. / Includes bibliographical references. / by Kerstin Leigh Haug. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2010. / Vita. Page 213 blank. Cataloged from PDF version of thesis. / Includes bibliographical references. / The uranium(III) tris(anilide) complex (THF)U(N[t-Bu]Ar) 3 reacts with MN 3 (M = Na, [N(n-Bu) 4]) to form the bimetallic diuranium(IV/IV) salts M[(p-N)(U(N[t-Bu]Ar) 3)2]. The stability of the U=N=U core across multiple charge states is illustrated by stepwise chemical oxidation of Na[(p- N)(U(N[t-Bu]Ar) 3)2] to the corresponding neutral diuranium(V/IV) and cationic diuranium(V/V) derivatives. Metallonitrene-like reactivity for [(p-N)(U(N[t-Bu]Ar) 3)2][B(ArF) 4] is demonstrated by its reaction with NaCN. The uranium(IV) azide complex (N3)U(N[t-Bu]Ar)3 is prepared by the reaction of the uranium(IV) iodide complex IU(N[t-Bu]Ar)3 with NaN3. Photolysis or reduction of (N3)U(N[t-Bu]Ar) 3 leads to the bimetallic p-nitride system [(-N)(U(N[t-Bu]Ar) 3)2]". The reaction of (THF)U(N[t-Bu]Ar) 3 with the azidoborate salt [N(n-Bu) 4] [(C6F5)3B(N 3)] provides the uranium(V) nitridoborate complex [N(n-Bu) 4] [(C6F5)3BNU(N[t-Bu]Ar) 3], which leads to the neutral uranium(VI) derivative (C6F5)3BNU(N[t-Bu]Ar) 3 by way of le oxidation. A system of uranium complexes featuring bidentate anilide ligands has been developed. The syntheses of the bis(anilide) complexes [(Et20),Li][I2U(N[R]ArMeL)2] and 12U(N[R]ArMeL)2, and the tris(anilide) complexes U(N[R]ArMeL)3 and U(N[Np]ArMeL)3 are described. The N-tert-butylanilide derivative U(N[R]ArMeL)3 fails to react with a host of small molecule substrates but does react with AgOTf to form the separated ion pair [U(N[R]ArMeL)3][OTf], suggesting a high degree of steric encumbrance about the metal center. The N-neopentylanilide derivative U(N[Np]ArMeL)3 reacts with pyridine-N-oxide to form the uranium(V) terminal oxo complex OU(N[Np]ArMeL)3, and with NaN3 to provide the "-ate" complex [Na(THF)6] [(p, T - N3 )(U(N[Np]ArMeL)3)2]- The tungsten(VI) terminal nitride complex NW(N[t-Bu]Ar) 3 is obtained in low but reproducible yield through a route independent of dinitrogen chemistry. The reaction of NW(N[t-Bu]Ar) 3 with electrophiles R-X (R-X = PhC(O)OTf; Mel) provides the four-coordinate imido salts [RNW(N[t-Bu]Ar) 3][X]. The siloxy-substituted ketimide complex Ph(Me 3SiO)CNW(N[t-Bu]Ar) 3 is obtained by reduction and silylation of the benzoylimido salt. In contrast to the chemistry displayed by a related Mo-based system, no reactions that lead to the elimination of PhCN from Ph(Me 3SiO)CNW(N[t-Bu]Ar)3 were uncovered. The parent ketimide complex H2CNW(N[t- Bu]Ar)3 reacts with electrophiles R'-X (R'-X = Me3SiOTf; [Ph 2P][AlC4l4) through the ketimide carbon, providing the substituted methylimido salts [R'CH2NW(N[t-Bu]Ar) 3][X], which in turn provide the substituted ketimide complexes R'(H)CNW(N[t-Bu]Ar) 3 by deprotonation. / Ph.D.

Thesis: Ph. D. in Physical Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references. / The primary focus of this thesis is to synthesize biocompatible luminescent nanocrystals for visible and short-wave infrared (1-2 [mu]m, SWIR) imaging applications. Quantum dots (QDs) have been promising fluorescent probes for biomedical imaging due to their high quantum yield (QY), narrow photoluminescence spectra, and excellent photostability. However, challenges remain to be solved to transfer the as-synthesized hydrophobic QD to aqueous solutions while maintaining the high QY and a compact size. This study involves the design and synthesis of a novel ligand that can be introduced to the established QD synthesis, producing norbornene functionalized QDs that can be readily phase transferred into water via norbornene/tetrazine click chemistry, meanwhile allowing flexible functionalization of the QDs by incorporating a functional group on the hydrophilic chain. This ligand system can be applied to a variety of carboxylic-ligand-stabilized QDs, with emission spectra spanning the visible and the SWIR region. The resulting water-soluble QDs exhibit a high QY, a small hydrodynamic diameter (HD), and excellent colloidal stability and pH stability. Further in vitro cell labeling experiments using azido-functionalized QDs demonstrates their potential for cell targeting applications. As in vivo imaging in the SWIR range has further reduced background noise from tissue scattering compared to traditional visible and near infrared (0.7-1 tm, NIR) imaging, images of higher contrast and better resolution can be readily obtained. The next challenge is to develop SWIR emitters that have high quantum efficiency and minimal toxicity, which is of critical importance in order to promote this technology for clinical applications. Our study found that the emission of luminescent gold nanoclusters can be tuned from the visible to the SWIR region by proper selection of ligands and post ligand modifications. The SWIR-emitting gold nanoclusters have a good QY, a HD that is small enough that they exhibit a rapid renal clearance, and images taken in the SWIR region show better resolution of the blood vessels than in the NIR region. / by Yue Chen. / Ph. D. in Physical Chemistry

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1941. / Vita. / Includes bibliographical references (leaves 67-69). / by John Humfrey. / Sc.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Vita. / Includes bibliographical references. / Pd-catalyzed cross-coupling processes have become one of the most important and useful class of transformations in organic synthesis in the past 25 years. Supporting ligand design has been crucial in developing more effective catalysts. One highly effective class of ligand is that of biaryl phosphines. Herein are presented experimental and theoretical structural data on this class of phosphine that aids in elucidating what aspects of ligand architecture are beneficial for catalyst stability and reactivity. Additionally, examples of traditionally difficult Suzuki-Miyaura reactions are presented along with a fluorescent sensor that can be used to monitor boronic acid consumption in Suzuki-Miyaura reactions in situ. Finally, a rationale behind the resistance of dialkylbiaryl phosphines toward oxidation by molecular oxidation is described. Chapter 1. Expansion of the Suzuki-Miyaura Coupling Reaction. Chapter 2. X-Ray Crystal Structures of Biaryl Phosphine Pd(0) and Pd(II) Complexes. Chapter 3. Structural Insights into Active Catalyst Structures and Oxidative Addition to Biaryl Phosphine-Palladium Complexes via Density Functional Theory and Experimental Studies. / (cont.) Chapter 4. Structural Insights into Amine Binding to Biaryl Phosphine-Palladium Complexes via Density Functional Theory and Experimental Studies. Chapter 5. Experimental and Theoretical Analysis of an Arene/Phosphine Ligated Pd(I) Dimer. Chapter 6. A Rationale for the Resistance of Dialkylbiaryl Phosphines Toward Oxidation by Molecular Oxygen. Chapter 7. Benchtop Monitoring of Reaction Progress via Visual Recognition with a Handheld UV Lamp: In Situ Sensing of Boronic Acids in the Suzuki-Miyaura Reaction. / Timothy E. Barder. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999. / Includes bibliographical references. / by Shuang Qiao. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2003. / Vita. / Includes bibliographical references. / New methods for Pd-catalyzed cross-coupling reactions of aryl halides or arenesulfonates are described. Key to the success of these transformations is the proper choice of ligand and reaction conditions. Palladium catalysts supported by bulky, monodentate phosphine ligands with a biaryl backbone or the bidentate ligand, Xantphos, effectively promote the formation of ca-aryl carbonyl compounds. Base-sensitive functional groups are better tolerated when a weak base, such as K3PO4, is used. One of the most difficult transformations in Pd catalysis, the intermolecular C-O bond formation between primary alcohols and electron-neutral or even electron-rich aryl halides, was effectively promoted by the use of a new generation of ligands, 3-methyl-2-di-t-butylphosphinobiaryl. The one-step synthesis of ligands from cheap starting materials, as well as the mild reaction conditions employed for the coupling reactions, enables the practical use of Pd catalysis to access aryl alkyl ethers for the first time. Continuing study of Pd-catalyzed C-N bond-forming processes using biaryl monophosphine ligands led to the discovery of a structural derivative of these ligands, 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl. This ligand, in combination with a Pd source, produces a catalyst system with both a greater degree of activity and of stability than those that use our previous ligands. Substrates that were not amenable to Pd catalysis previously are reexamined using this new catalyst system, and excellent results are obtained. / by Xiaohua Huang. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004. / MIT Institute Archives copy has p. 191-192 bound between p. 188 and p. 189. / Vita. / Includes bibliographical references. / Chapter 1. Fluorescence-Based Detection Methodologies for Nitric Oxide: A Review. Chapter 2. Cobalt Chemistry with Mixed Aminotroponimine Salicylaldimine Ligands: Synthesis, Characterization, and Nitric Oxide Reactivity. Chapter 3. Carboxylate-Bridged Dimetallic Complexes as Potential Nitric Oxide Sensors. Chapter 4. Dirhodium Tetracarboxylate Scaffolds as Reversible Fluorescence- Based Nitric Oxide Sensors. / by Scott A. Hilderbrand. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student submitted PDF version of thesis. / Includes bibliographical references (p. 121-127). / Conventional single-molecule fluorescence spectroscopy is limited in temporal resolution by the need to collect enough photons to measure a spectrum, in frequency resolution by the dispersing power of the spectrometer, and by environmental conditions by the need to immobilize the chromophore on a substrate. In this thesis, we use the recently developed technique of photon-correlation Fourier spectroscopy (PCFS) to circumvent each of these limitations. PCFS combines the high temporal resolution of photon correlation measurements with the high frequency resolution of Fourier spectroscopy. The experimental setup consists of a Michelson interferometer where the two outputs are detected with avalanche photodiodes and cross-correlated with a hardware autocorrelator card. The interferometer maps spectral changes into intensity changes which can be measured with high temporal resolution by the autocorrelator. The distribution of spectral changes between photons with a given temporal separation determines the degree of correlation in the interferogram. By measuring the intensity correlation at different interferometer positions while dithering one mirror, a time dependent spectral correlation function is obtained. From this, we learn about the temporal evolution of the emission line shape at timescales approaching the lifetime of the emitter. In this body of work, we both apply PCFS to study low temperature colloidal quantum dots and extend the technique to extract spectral lineshapes and dynamics of single quantum dots freely diffusing in solution. In solution, spectral correlations originating from the same quantum dot are statistically enhanced and separable from the ensemble using intensity fluctuations from diffusion. We are able to use spectral correlations from many diffusing chromophores to determine the average single chromophore spectral correlation. This thesis begins with a review of spectral dynamics in quantum dots in Chapter 1. Chapters 2 and 3 describe the theoretical and experimental implementation of PCFS. Chapters 4 and 5 cover numerical simulations and experimental demonstrations of the extension of PCFS to single quantum dots obscured by an ensemble in solution. Finally, chapter 6 applies PCFS to single quantum dots at liquid helium temperatures. / by Lisa Faye Marshall. / Ph.D.