scholarly journals Charge Transfer in Uranyl(VI) Halides [UO2X4]2−(X = F, Cl, Br, and I). A Quantum Chemical Study of the Absorption Spectra

2010 ◽  
Vol 114 (10) ◽  
pp. 3615-3621 ◽  
Author(s):  
Fernando Ruipérez ◽  
Ulf Wahlgren
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Chemical Study

Photocolouration of 2,4,4,6-Tetraaryl-4H-thiopyrans: A Semiempirical Quantum Chemical Study

1994 ◽  
Vol 59 (5) ◽  
pp. 1115-1125 ◽  
Author(s):  
Stanislav Böhm ◽  
Pavel Šebek ◽  
Stanislav Nešpůrek ◽  
Josef Kuthan
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Quantum Chemical ◽  
Electronic Absorption Spectra ◽  
Quantum Chemical Study ◽  
Theoretical Data ◽  
Chemical Study ◽  
Pm3 Method ◽  
Uv Illumination

Molecular geometries of 4H-thiopyrans Ia, Ib and their possible photoisomers IVa - VIIa and IVb - VIIb were optimized by the AM1 and PM3 method and used for the calculation of electronic absorption spectra by the CNDO/S-CI procedure. Comparison of the theoretical data with experimental UV-VIS absorption spectra made it possible to postulate two probable mechanisms of the photocolouration of Ia, Ib caused by sunlight or UV-illumination.

Photocolouration of 2,4,4,6-Tetraaryl-1,4-dihydropyridines: A Semiempirical Quantum Chemical Study

1994 ◽  
Vol 59 (2) ◽  
pp. 262-272 ◽  
Author(s):  
Stanislav Böhm ◽  
Michal Hocek ◽  
Stanislav Nešpůrek ◽  
Josef Kuthan
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Quantum Chemical ◽  
Spectroscopic Data ◽  
Electronic Absorption Spectra ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Probable Mechanism ◽  
Pm3 Method ◽  
Uv Illumination

Molecular geometries of 1,4-dihydropyridines Ia, Ib and their possible photoisomers IIa - Va and IIb - Vb were optimized by the PM3 method. The electronic absorption spectra were calculated by the CNDO/S-CI procedure and compared with the experimental spectroscopic data. A probable mechanism of the photocolouration of Ia, Ib, caused by sunlight or UV illumination, is proposed, and structures IIIa, IIIb are assigned to violet or green coloured species.

IMPORTANCE OF CHARGE TRANSFER EXCITATIONS IN DNA ELECTRON SPECTRUM: A ZINDO SEMIEMPIRICAL QUANTUM-CHEMICAL STUDY

2004 ◽  
Vol 18 (16) ◽  
pp. 825-831 ◽  
Author(s):  
E. B. STARIKOV
Keyword(s):  
Charge Transfer ◽  
Quantum Chemical ◽  
Spectral Band ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Molecular Orbitals ◽  
Base Pairs ◽  
Purine Base ◽  
Dna Conformations

Electron spectra of DNA model compounds, adenosine-thymidine and guanosine-cytidine nucleoside base pairs, as well as the relevant homogeneous stacked base pair steps in A-DNA and B-DNA conformations, were investigated using ZINDO semiempirical quantum-chemical method. This work confirms that, in DNA with intact Watson–Crick hydrogen bonding and base stacking, the highest occupied molecular orbitals (HOMO) are residing on purine base residues, whereas the lowest unoccupied molecular orbitals (LUMO) — on pyrimidine base residues. In general, the present results are satisfactorily comparable with the available experimental data. The role of charge transfer excitations in the polymer DNA 260 nm spectral band is discussed.

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