Computational studies of reactive oxygen and sulfur species
Item
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Title
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Computational studies of reactive oxygen and sulfur species
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Identifier
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d_2009_2013:3a437d119677:10986
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identifier
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11343
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Creator
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Castillo Aguilar, Alvaro,
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Contributor
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Alexander Greer
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Date
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2011
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Language
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English
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Publisher
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City University of New York.
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Subject
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Inorganic chemistry | Nanotechnology | Organic chemistry | Computational Chemistry | Nanotubes | Reaction Mechanisms | Reactive Species | Singlet Oxygen | Sulfur
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Abstract
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In this thesis, we summarized the use of computational chemistry methods to provide insight into the chemistry of reactive intermediates species like singlet oxygen, thiozone, radical and diradicals of mercapto-quinones, and benzyl alkynyl sulfides anions. The theoretical methods used included Density Functional Theory, and hybrid [Molecular Orbital:Molecular Orbital] methods and the Conductor-like Polarizable Continuum Model for condensed phase calculations.;The first chapter deals with carbon nanotubes as a class of host cavities to encapsulate the unstable molecule thiozone (S3). We computed single-walled carbon nanotube (SWNT)--thiozone pairs. Nanotube diameter selectivity for isomerization of the C2v form of S3 to the D3h form proved to be elusive. 1,2,3-Thiozonide formation took place on the convex side of nanotubes of low tube radii, such as the armchair (4,4) and (5,5) SWNTs. The second chapter focused on singlet oxygen release from a naphthalene endoperoxide which bears a flexible (CH2)22 polymethylene "lid". Monte Carlo and ONIOM calculations that incorporated semiempirical and density functional theory were used in the study. Interestingly, the polymethylene chain appears to function as a gatekeeper for the oxygen, where, instead of coming full circle, a semi-circle rotation of the polymethylene bridge protected the peroxide group, limiting the dissociation of 1O2 from the naphthalene site. The third chapter deals with condensed-phase calculations of the reaction of aryl substituted benzyl 1-alkynyl sulfides with potassium t-methoxide in acetonitrile. This reaction produces 2-aryl 2,3-dihydrothiophene products. Experimental evidence (from our collaborators) indicates that there is a rapid exchange of protons and tautomerism of the alkynyl unit prior to cyclization to the dihydro-thiophenes. The fourth and last chapter is devoted to DFT calculations of quinones, radicals and diradicals. Calculations on these reactive species arising from mercapto- and bismercaptocatechols were conducted seeking to provide insight into their relative stability.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Chemistry
