Theoretical Studies of Reactive Intermediates in Complex Reaction Mechanisms
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The Ohio State University / OhioLINK
2018
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=osu1531497707269833 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu15314977072698332021-08-03T07:07:31Z Theoretical Studies of Reactive Intermediates in Complex Reaction Mechanisms Coldren, William Henry Chemistry Reactive Intermediates Computational Chemistry Organophosphorus Nerve Agent Chemistry Carbenes Radicals Molecular Dynamics The mechanistic transformations of three fundamental classes of reactive intermediates are explored: singlet and triplet carbenes, carbene radical cations, and carbon-centered radicals. Through a marriage of theory and ultrafast spectroscopy, the identities of unique carbene species and photochemical transformations were characterized from nitrogenous (diazo and diazirine) precursors. The photochemistry of a novel trifluoro-diazo, carbenic precursor (ethyl 2-diazo-3,3,3-trifluoropropanoate) is explored by ultrafast time-resolved infrared spectroscopy in multiple solvents and the results do not reveal a prototypical 1,2-migration product via rearrangement in the excited state or through a carbene intermediate. The primary photochemical process is the interconversion of a diazo functional group to the corresponding diazirine. A completely new mechanistic pathway is detailed for the conversion of diazo and diazirine containing nitrogenous precursors to their corresponding products. This theoretical report accounts for the partially unexplained and curious bifurcation in photochemical vs thermal decomposition of nitrogenous precursors. Using a phenanthrene precursor, the first ultrafast time-resolved spectroscopic observation of a vinyl carbene (singlet ¿-methylbenzylidenecarbene) is reported and the results are supported and rationalized by computational data.Electronic factors affecting the regioselectivity of aryl radical hydrogen-atom abstraction reactions in benzyl-alkyl tethered species is explored in order to guide efforts of selective remote C–H functionalizations. The system can be biased towards or away from the standard abstraction pathway by the use of electron-donating and electron-withdrawing groups strategically placed on the benzene ring. The mechanistic aspects of the oxidative transformation of C2 symmetric o-aminophenol species and C3 symmetric formyl fragments to form benzobisxazole based covalent organic frameworks (COFs). Computational data strongly suggest that such reactions occur via a putative radical species that is stabilized by an active captodative effect. The nature of the catalysts used affects the efficiency of this reaction and the overall crystallinity and porosity of desired COFs.Preliminary investigations into the difficulty of resurrecting aged huAChE based on the nature of organophosphorus chemical nerve agents are presented. The active site is severely contracted for a methyl phosphonate aged enzyme compared to an alkyl phosphate aged enzyme. In silico prediction of factors influencing the binding and activity of novel quinone methide precursors as potential therapeutics is investigated with biophysical molecular dynamics simulations and in the case of one substrate, the efficacious enantiomer was predicted a priori to experimental in vitro screening. 2018 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1531497707269833 http://rave.ohiolink.edu/etdc/view?acc_num=osu1531497707269833 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Chemistry Reactive Intermediates Computational Chemistry Organophosphorus Nerve Agent Chemistry Carbenes Radicals Molecular Dynamics |
| spellingShingle |
Chemistry Reactive Intermediates Computational Chemistry Organophosphorus Nerve Agent Chemistry Carbenes Radicals Molecular Dynamics Coldren, William Henry Theoretical Studies of Reactive Intermediates in Complex Reaction Mechanisms |
| author |
Coldren, William Henry |
| author_facet |
Coldren, William Henry |
| author_sort |
Coldren, William Henry |
| title |
Theoretical Studies of Reactive Intermediates in Complex Reaction Mechanisms |
| title_short |
Theoretical Studies of Reactive Intermediates in Complex Reaction Mechanisms |
| title_full |
Theoretical Studies of Reactive Intermediates in Complex Reaction Mechanisms |
| title_fullStr |
Theoretical Studies of Reactive Intermediates in Complex Reaction Mechanisms |
| title_full_unstemmed |
Theoretical Studies of Reactive Intermediates in Complex Reaction Mechanisms |
| title_sort |
theoretical studies of reactive intermediates in complex reaction mechanisms |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2018 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1531497707269833 |
| work_keys_str_mv |
AT coldrenwilliamhenry theoreticalstudiesofreactiveintermediatesincomplexreactionmechanisms |
| _version_ |
1719454237196288000 |