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Table 3.3: Standard oxidation potentials corresponding to different one-electron
oxidation transitions computed using gas-phase detachment and ionization ener-gies
(see text).
Transition IE, eV E , V
D0 !cation 7.59 1:66 0:49
D1 ! cation 6.07 0:81 0:44
D2 ! cation 4.22 0:23 0:39
S1 !D1 1.29 1:87 0:30
S1 !D2 3.14 0:83 0:35
14 organic molecules with their gas-phase ionization energies. Applying this equation,
we arrive at the values of E summarized in Table 3.3. Eq. (3.1) was derived using IEs
in the range of 5.6–9.0 eV and its application to lower values (such as S1 !D1;2 transi-tions
from Table 3.3) assumes that the trend can be extrapolated. Thus, estimations for
the lower IEs are of a semiquantitative value only.
Oxidation of the ground-state doublet radical (D0) corresponds to E = 1:66 V,
which is much larger than E of the strongest oxidizing agent employed in Ref. 13
(K3Fe(CN)6, E = 0:42 V). However, the oxidation of the electronically excited neutral
radical corresponds to E = 0:81 and E = 0:12 V for the D1 and D2 states, respec-tively.
Thus, electronically excited doublet radical (in the D2 state) can be oxidized even
by the weakest oxidizing agent from Ref. 13 (E = 0:32 V), whereas the oxidation of
D1 is less likely. Finally, the electronically excited anion can be easily oxidized produc-ing
excited states of the doublet (E = 1:87 and E = 0:83 V for D1 and D2 states,
respectively). Note that the S1 !D0 transition is spontaneous in the gas phase and does
not require the presence of oxidizing agents due to the autoionizing nature of S1. By
95
Object Description
| Title | Development of predictive electronic structure methods and their application to atmospheric chemistry, combustion, and biologically relevant systems |
| Author | Epifanovskiy, Evgeny |
| Author email | epifanov@usc.edu; epifanov@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Chemistry |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2011-03-21 |
| Date submitted | 2011 |
| Restricted until | Unrestricted |
| Date published | 2011-04-28 |
| Advisor (committee chair) | Krylov, Anna I. |
| Advisor (committee member) |
Wittig, Curt Johnson, Clifford |
| Abstract | This work demonstrates electronic structure techniques that enable predictive modeling of the properties of biologically relevant species. Chapters 2 and 3 present studies of the electronically excited and detached states of the chromophore of the green fluorescent protein, the mechanism of its cis-trans isomerization, and the effect of oxidation. The bright excited ππ∗ state of the chromophore in the gas phase located at 2.6 eV is found to have an autoionizing resonance nature as it lies above the electron detachment level at 2.4 eV. The calculation of the barrier for the ground-state cis-trans isomerization of the chromophore yields 14.8 kcal/mol, which agrees with an experimental value of 15.4 kcal/mol; the electronic correlation and solvent stabilization are shown to have an important effect. In Chapter 3, a one-photon two-electron mechanism is proposed to explain the experimentally observed oxidative reddening of the chromophore. Chapter 4 considers the excited states of uracil. It demonstrates the role of the one-electron basis set and triples excitations in obtaining the converged values of the excitation energies of the nπ∗ and ππ∗ states. The effects of the solvent and protein environment are included in some of the models.; Chapter 5 describes an implementation of the algorithm for locating and exploring intersection seams between potential energy surfaces. The theory is illustrated with examples from atmospheric and combustion chemistry. |
| Keyword | electronic structure theory; coupled clusters theory; equation of motion theory; organic chromophore; green fluorescent protein; uracil |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m3801 |
| Contributing entity | University of Southern California |
| Rights | Epifanovskiy, Evgeny |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Epifanovskiy-4557 |
| Archival file | uscthesesreloadpub_Volume14/etd-Epifanovskiy-4557.pdf |
Description
| Title | Page 105 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | Table 3.3: Standard oxidation potentials corresponding to different one-electron oxidation transitions computed using gas-phase detachment and ionization ener-gies (see text). Transition IE, eV E , V D0 !cation 7.59 1:66 0:49 D1 ! cation 6.07 0:81 0:44 D2 ! cation 4.22 0:23 0:39 S1 !D1 1.29 1:87 0:30 S1 !D2 3.14 0:83 0:35 14 organic molecules with their gas-phase ionization energies. Applying this equation, we arrive at the values of E summarized in Table 3.3. Eq. (3.1) was derived using IEs in the range of 5.6–9.0 eV and its application to lower values (such as S1 !D1;2 transi-tions from Table 3.3) assumes that the trend can be extrapolated. Thus, estimations for the lower IEs are of a semiquantitative value only. Oxidation of the ground-state doublet radical (D0) corresponds to E = 1:66 V, which is much larger than E of the strongest oxidizing agent employed in Ref. 13 (K3Fe(CN)6, E = 0:42 V). However, the oxidation of the electronically excited neutral radical corresponds to E = 0:81 and E = 0:12 V for the D1 and D2 states, respec-tively. Thus, electronically excited doublet radical (in the D2 state) can be oxidized even by the weakest oxidizing agent from Ref. 13 (E = 0:32 V), whereas the oxidation of D1 is less likely. Finally, the electronically excited anion can be easily oxidized produc-ing excited states of the doublet (E = 1:87 and E = 0:83 V for D1 and D2 states, respectively). Note that the S1 !D0 transition is spontaneous in the gas phase and does not require the presence of oxidizing agents due to the autoionizing nature of S1. By 95 |
