scholarly journals Electronic Absorption Spectra of Some Triazolopyrimidine Derivatives

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Hussein Moustafa ◽  
M. F. Shibl ◽  
Rifaat Hilal ◽  
Laila I. Ali ◽  
Sheimaa Abdel Halim
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Dipole Moments ◽  
Molecular Orbital Calculations ◽  
Transition Energies ◽  
Density Distributions ◽  
Nonpolar Solvents ◽  
Experimental Transition

The electronic absorption spectra of triazolo pyrimidine and some of its derivatives were measured in polar as well as nonpolar solvents. Assignment of the observed transitions is facilitated via molecular orbital calculations. Charge density distributions, dipole moments, and the extent of delocalization of the MOS were used to interpret the observed solvent effects. The observed transitions are assigned as charge transfer (CT), localized, and delocalized according to the contribution of the various configurations in the CI-states. The correspondence between the calculated and experimental transition energies is satisfactory.

Complexes moléculaires d'hétérocycles soufrés et oxygénés. Étude spectrophotométrique de bandes de transfert de charge multiples

1982 ◽  
Vol 60 (7) ◽  
pp. 862-871 ◽  
Author(s):  
Jean-Paul Canselier ◽  
Serge Domenech ◽  
Štefan Stankovsky ◽  
Sabine Gautier
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Molecular Complexes ◽  
The Other ◽  
Ionization Potentials ◽  
Nonpolar Solvents ◽  
Other Hand ◽  
The One

As with benzenoid donors, the electronic absorption spectra of the molecular complexes of simple or condensed sulfur or oxygen-containing five-membered heterocycles with TCNE (or DDQ) often show two charge-transfer bands. In many cases, the knowledge of the actual frequencies requires a technique of resolution. The results so obtained are correlated with the ionization potentials of donors on the one hand, and the refractivity of nonpolar solvents on the other hand.

The Electronic Absorption Spectra of Some N-Substituted Pyrroles—Molecular Orbital Calculations

1982 ◽  
Vol 36 (3) ◽  
pp. 297-301 ◽  
Author(s):  
R. Abu-Eittah ◽  
R. Hilal ◽  
M. S. El-Shall
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Absorption ◽  
Electronic Transition ◽  
Electronic Absorption Spectra ◽  
Experimental Results ◽  
Electronic Transitions ◽  
Molecular Orbital Calculations ◽  
Nonpolar Solvents ◽  
State Functions

The electronic absorption spectra of N-phenylpyrrole and some of its parasubstituted derivatives have been investigated in polar and nonpolar solvents. Such an investigation could predict the extent of resonance interaction between the pyrryl and phenyl moieties of the composite molecule. The direction and polarization of the electronic transitions were predicted. Molecular orbital calculations using the SCF-CI procedures were performed on N-phenylpyrrole and some of its p-substituted derivatives. The state functions and energies were computed. The weight of each configuration was evidence for the direction of the electronic transition. The correspondence between the theoretical and experimental results is satisfactory.

The electronic absorption spectra of some coumarins. A molecular orbital treatment

1985 ◽  
Vol 63 (6) ◽  
pp. 1173-1179 ◽  
Author(s):  
Rafie H. Abu-Eittah ◽  
Bahgat Ali H. El-Tawil
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Absorption ◽  
Transition Energy ◽  
Electronic Absorption Spectra ◽  
Band Intensity ◽  
Molecular Orbital Calculations ◽  
Atomic Orbitals ◽  
Experimental Transition

The electronic absorption spectra of coumarin and its derivatives umbelliferone (6-hydroxycoumarin), esculetin (6,7-dihydroxycoumarin), and scopoletin (6-methoxy-7-hydroxycoumarin) were investigated. The n → π* transition was not observed in the spectrum of coumarin but was observed in the spectra of some of its derivatives. Molecular orbital calculations, using the INDO procedures, were carried out on coumarin and some of its derivatives. The activities of the different sites of the molecules are discussed in terms of the coefficients of the atomic orbitals constituting the HOMO and the LUMO. The correspondence between the calculated and experimental transition energy and band intensity is satisfactory.

Optical Spectroscopy of Mixed Metamagnetic FexCo1-xCl2 Crystals

1980 ◽  
Vol 35 (10) ◽  
pp. 1013-1019 ◽  
Author(s):  
Friedrich Seitz ◽  
Terence E. Wood ◽  
Peter Day
Keyword(s):  
Charge Transfer ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Absorption Spectra ◽  
Optical Spectroscopy ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Broad Band ◽  
Mixed Crystals ◽  
Magnetic Exchange

Abstract Electronic absorption spectra are reported for single crystals of composition FexCo1-xCl2 as a function of temperature from 300 K to 4 K. A broad band at 436 nm is assigned to Fe (II) → Co (II) charge transfer and the temperature dependence of its intensity is related to the magnetic exchange between the ions. The 2T1g(2H) excitation of Co (II) in the mixed crystals has an unusual temperature dependence which correlates with the Néel temperature.

Dipole moments and electronic absorption spectra of aryltricyanoethylenes

1970 ◽  
Vol 66 ◽  
pp. 769 ◽  
Author(s):  
Israel Agranat ◽  
Zvi Rappoport ◽  
Hannah Weiler-Feilchenfeld
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Dipole Moments

Spectra of the 1:1 and 3:1 solid complexes of coronene-TCNQ

1977 ◽  
Vol 55 (21) ◽  
pp. 3712-3716 ◽  
Author(s):  
Kim Doan Truong ◽  
André D. Bandrauk
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Ground State ◽  
Electronic Absorption Spectra ◽  
Charge Transfer Band ◽  
Out Of Plane ◽  
The Individual ◽  
A Charge ◽  
Solid Complexes

Two new solid TCNQ complexes have been isolated, coronene–TCNQ 1:1 and 3:1. The infrared and electronic absorption spectra are presented for the two different stoichiometries. From these spectra we infer that the complexes are covalent in the ground state with a charge transfer band appearing at 730 nm. The out of plane vibrations of the individual molecules are noticeably perturbed upon complexation.

Electronic absorption spectra of charge transfer complexes derived from ferrocene and functionally substituted tetrahalopropanes

1987 ◽  
Vol 36 (3) ◽  
pp. 602-604
Author(s):  
F. K. Velichko ◽  
T. T. Vasil'eva ◽  
V. A. Kochetkova ◽  
L. V. Vinogradova ◽  
L. V. Balabanova ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Charge Transfer Complexes
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