A Combined ab initio and Density Functional Study of the Electronic Structure of Thymine and 2-Thiothymine Radicals

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Title:A Combined ab initio and Density Functional Study of the Electronic Structure of Thymine and 2-Thiothymine Radicals
Creators:
Vianello, Robert
Maksić, Zvonimir B.
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 68, 12, pp. 2322-2334
Uncontrolled Keywords:<i>Ab initio</i> calculations, Ionization potentials, Pyrimidines, Nucleic acids, DFT, Thymine, DNA, Nucleobases, Spin density, 2-Thiothymine

Abstract

The electronic and energetic properties of thymine (<strong>1</strong>) and 2-thiothymine (<strong>2</strong>) and their neutral and positively charged radicals are considered by a combined <i>ab initio</i> and density functional theory approach. It is conclusively shown that ionization of <strong>1</strong> and <strong>2</strong> greatly facilitates deprotonation of the formed radical cations thus making the proton transfer between charged and neutral precursor species thermodynamically favourable. The adiabatic ionization potential of <strong>1</strong> and <strong>2</strong> are analysed. It appears that ADIP(<strong>1</strong>) is larger than ADIP(<strong>2</strong>) by 10&nbsp;kcal/mol, because of greater stability of the highest occupied molecular orbital (HOMO) of the former. It is also shown beyond any doubt that the spin density in neutral and cationic radical of <strong>2</strong> is almost exclusively placed on the σ-3p AO of sulfur implying that these two systems represent rather rare sigma-radicals. In contrast, the spin density of radicals of <strong>1</strong> is distributed over their π-network. <p>

Title:A Combined ab initio and Density Functional Study of the Electronic Structure of Thymine and 2-Thiothymine Radicals
Creators:
Vianello, Robert
Maksić, Zvonimir B.
Uncontrolled Keywords:<i>Ab initio</i> calculations, Ionization potentials, Pyrimidines, Nucleic acids, DFT, Thymine, DNA, Nucleobases, Spin density, 2-Thiothymine
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:68
Number:12
Page Range:pp. 2322-2334
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20032322UNSPECIFIED
ID Code:2187
Item Type:Article
Deposited On:06 Feb 2009 17:16
Last Modified:06 Feb 2009 16:16

Citation

Vianello, Robert; Maksić, Zvonimir B. (2003) A Combined ab initio and Density Functional Study of the Electronic Structure of Thymine and 2-Thiothymine Radicals. Collection of Czechoslovak Chemical Communications, 68 (12). pp. 2322-2334. ISSN 0010-0765

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