Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007. / Vita. / Includes bibliographical references. / Broadly defined this thesis has focused on the design and study of molecular catalysts that engender multi-electron reactions and photoreactions on small molecule substrates relevant to solar energy conversion. Specifically the molecular design elements employed have focused on bimetallic complexes of late transition metals that exhibit an unusual two-electron mixed valence ground state. Initial studies focused on the mechanistic elucidation of the reported photocatalytic production of hydrogen from homogeneous hydrohalic acid solution using a two-electron mixed valence dirhodium complex. Studies aimed at understanding and improving the photochemical quantum efficiency for challenging M-X (X = CI, Br-) bond photoactivations were undertaken by incorporating gold into a heterobimetallic rhodium-gold construct. Additionally the organometallic reactivity of two-electron mixed valence diiridium cores was explored with a specific emphasis on C-H bond activations in order to extend the cooperative bimetallic reactivity observed in the dirhodium systems beyond HX and H2 substrates to alkanes and arenes. / by Arthur J. Esswein. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, February 2013. / "February 2013." Vita. Cataloged from PDF version of thesis. / Includes bibliographical references (p. 87-92). / Two different classes of polymers were pursued as candidates for materials possessing porosity, conductivity, and crystalline order. Attempts were made with hexaazatrinaphthylene- and dibenzotetrathiafulvalene-based precursors with boronic acids to prepare covalent-organic frameworks (COFs) possessing boroxole linkages. After preparing the precursors, several different reaction conditions were attempted, but the desired COFs proved elusive. The second class of materials was tetrathiafulvalene-based metal-organic frameworks (MOFs). These materials were constructed with tetrathiafulvalene tetrabenzoic acid and zinc, cobalt, and manganese nitrate to give helical structures with approximately cylindrical pores. This structure type has one close S-S contact of 3.8 Å which acts as a potential avenue for charge transfer. Gas sorption measurements suggest that the materials retain porosity upon evacuation. The material possesses high charge mobility as determined by flash photolysis time-resolved microwave conductivity measurements. / by Tarun Chandru Narayan. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1994. / Includes bibliographical references. / by Daniel M. Giaquinta. / Ph.D.

Thesis (B.S.) Massachusetts Institute of Technology. Dept. of Chemistry, 1948. / MIT copy bound with: Solvent interaction with polymethylmethacrylate / Robert P. Auty. 1948. / Vita. / Bibliography: leaves 46-47. / by Elias James Corey, Jr. / B.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1996. / Includes bibliographical references. / by Christopher D. Bayne. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009. / Vita. / Includes bibliographical references. / Since the discovery of conducting polymers (CPs), efforts have focused on synthesizing CPs with improved processability, and finding new applications for the unique conjugated structure of CPs. This Thesis details the development of new CP based materials by block copolymerization and/or end-capping with polymerizable units. In Chapter 1, three different norbornene derivatives having phenylene-heterocyclic moieties were copolymerized with either norbornene or 7-oxanorbornene derivatives via ring-opening metathesis polymerization (ROMP). Block copolymers' stabilities and solubilities could be improved by hydrogenation of double bonds in the polymer backbone. The block copolymers were subsequently cross-linked by anodic electropolymerization of phenylene-heterocycle moieties, affording conducting polymers. All of these three block copolymers were readily deposited on the electrode substrates, and their cyclic voltammograms revealed an excellent reversibility in the redox cycles. The deposited polymer films also showed reversible color change between oxidized and neutral states. In Chapter 2, three different conjugated polymers having interesting properties and/or useful applications were synthesized and end-capped with norbornene using the hydroarylation reaction. These norbornene end-capped CPs became macroinitiators using Grubbs' catalysts, and they were used to prepare block copolymers by polymerizing ROMP monomers. / (cont.) Prepared block copolymers were rubbery like outer elastomers while having similar optical properties to their center CPs. In Chapter 3, three different iptycene-poly(phenylene ethynylene)s, which were known to form well-aligned and chain-extended structures in nematic liquid crystals (LCs), were synthesized and end-capped with the compound capable of strong hydrogen bonding. Then, LC-polymer gels were prepared to see their effect on the vertically aligned nematic liquid crystal display's switching speed, particularly relaxation time. Prepared LC mixtures had similar phase transition temperature to pure LC. Unfortunately, the polymers could not improve the LC's switching speed in the vertically aligned mode probably because these polymers could not form a stable physical gel state within the LC test cell. / by Hyun A. Kang. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2012. / 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. 117-136). / In this thesis, I implemented a method for performing electronic structure calculations, "Constrained Density Functional Theory-- Configuration Interaction" (CDFT-CI), which builds upon the computational strengths of Density Functional Theory and improves upon it by including higher level treatments of electronic correlation which are not readily available in Density-Functional Theory but are a keystone of wavefunction-based electronic structure methods. The method involves using CDFT to construct a small basis of hand-picked states which suffice to reasonably describe the static correlation present in a particular system, and efficiently computing electronic coupling elements between them. Analytical gradients were also implemented, involving computational effort roughly equivalent to the evaluation of an analytical Hessian for an ordinary DFT calculation. The routines were implemented within Q-Chem in a fashion accessible to end users; calculations were performed to assess how CDFT-CI improves reaction transition state energies, and to assess its ability to produce conical intersections, as compared to ordinary DFT. The analytical gradients enabled optimization of reaction transition-state structures, as well as geometry optimization on electronic excited states, with good results. / by Benjamin James Kaduk. / Ph.D.

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

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005. / Includes bibliographical references (p. 267-279). / In this thesis, theoretical models and computer simulations are employed to study several problems of single-molecule spectroscopy and vibrational spectroscopy in condensed phases. The first part of the thesis concentrates on studying dynamic disorders probed by single molecule fluorescence spectroscopy. Event statistics and correlations of single-molecule fluorescence sequences of modulated reactions are evaluated for multi-channel model, diffusion-controlled reaction model, and stochastic rate model. Several event-related measurements, such as the on-time correlation and the two-event number density, are proposed to map out the memory function, which characterizes the correlation in the conformational fluctuations. A semiflexible Gaussian chain model is used to determine the statistics and correlations of single-molecule fluorescence resonant energy transfer (FRET) experiments on biological polymers. The distribution functions of the fluorescence lifetime and the FRET efficiency provide direct measures of the chain stiffness and their correlation functions probe the intra-chain dynamics at the single-molecule level. The fluorescence lifetime distribution is decomposed into high order memory functions that can be measured in single- molecule experiments. The scaling of the average fluorescence lifetime on the contour length is predicted with the semi-flexible Gaussian chain model and agrees favorably with recent experiments and computer simulations. / (cont.) To interpret the fluorescence measurements of the mechanical properties of double-stranded DNA, a worm-like chain model is used as a first-principle model to study double-stranded DNA under hydrodynamic flows. The second part of the thesis concentrates on nonperturbative vibrational energy relaxation (VER) effects of vibrational line shapes. In general, nonperturbative and non-Markovian VER effects are demonstrated more strongly on nonlinear vibrational line shapes than on linear absorption. / by Shilong Yang. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1983. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Thomas Edward D'Ambra. / Ph.D.