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PHOTOCHEMISTRY OF NUCLEIC ACIDS AND ENVIRONMENTAL POLLUTANTS

Brister, Matthew Michael
http://rave.ohiolink.edu/etdc/view?acc_num=case1523021339182475

Abstract Details

2018, Doctor of Philosophy, Case Western Reserve University, Chemistry.
This thesis will cover two different topics in photochemistry. The first will explore the photodynamical relationship of canonical nucleobases and their derivatives. Typically, most organic molecules are unstable under persistent irradiation with ultraviolet (UV) light. UV photons often break covalent bonds and induce a wide variety of chemical transformations. It is therefore remarkable that life is able to thrive under continuous exposure to electromagnetic radiation from the sun. This suggest that stability to UV radiation should have been a decisive selection criterion that determined the molecular architecture of the building blocks of life during prebiotic chemistry. Excitation with UVC light showed ultrafast relaxation pathways for potential prebiotic RNA candidates, uracil, uracil derivatives and nucleotides. In contrast, certain pyrimidine chromophores showed potential long-lived states as major or minor decay channels. The C2 position of the pyrimidine chromophore could be responsible for access to the long lived states such as the triplet manifold, while the C4 position allows access to the conical intersection that couple the pi,pi* singlet and ground state together. The other topic will investigate the photodynamic relationship of nitropolycyclic aromatic hydrocarbons (NPAHs). NPAHs are mutagenic and carcinogenic compounds that are environmental pollutants. These compounds are detected in airborne particles, the soil and from incomplete combustion of fossil fuels. Interest in these compounds extended to nitronapthalene, and monopyrene compounds but interest ebbed for the dinitropyrenes. Since these compounds are ubiquitous in the environment and reach the atmosphere, understanding their interaction with light is crucial. Therefore, increasing the photochemical knowledge for these NPAH compounds specifically dinitropyrenes is important to further understand the photo transformation of NPAHs in the environment. Excitation of 1,6-dinitropyrene with 425, 415, or 340 nm radiation leads to an increasing amount of radical production through photodissociation. It was determined that ultrafast branching of the excited-state population in the S1 state to populates the triplet state with about 90% yield and form a nitropyrenoxy radical in less than 10% yield. In addition, the degree of the NO2 group functionalization does not affect significantly the excited-state relaxation mechanism. However, the degree of substitution does influence the absorption and fluorescence spectra, the fluorescence, triplet, singlet oxygen, and photodegradation yields, as well as the relative yield of radical formation.
Carlos Crespo (Advisor)
Genevieve Sauve (Committee Chair)
Mary Barkley (Committee Member)
Eckhard Jankowsky (Committee Member)
Blanton Tolbert (Committee Member)
221 p.
Chemistry; Physical Chemistry
physical chemistry; photochemistry; nucleobases; dinitropyrene

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Citations

  • Brister, M. M. (2018). PHOTOCHEMISTRY OF NUCLEIC ACIDS AND ENVIRONMENTAL POLLUTANTS [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1523021339182475

    APA Style (7th edition)

  • Brister, Matthew. PHOTOCHEMISTRY OF NUCLEIC ACIDS AND ENVIRONMENTAL POLLUTANTS. 2018. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1523021339182475.

    MLA Style (8th edition)

  • Brister, Matthew. "PHOTOCHEMISTRY OF NUCLEIC ACIDS AND ENVIRONMENTAL POLLUTANTS." Doctoral dissertation, Case Western Reserve University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1523021339182475

    Chicago Manual of Style (17th edition)

case1523021339182475
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This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.