Electronic absorption spectra and π-electron structure of 2-propenylidene-1,2-dihydropyridine and its derivatives

1979 ◽  
Vol 44 (3) ◽  
pp. 884-894 ◽  
Author(s):  
Josef Kuthan ◽  
Dušan Ilavský ◽  
Jiří Krechl
Keyword(s):  
Absorption Spectra ◽  
Satisfactory Agreement ◽  
Electronic Absorption ◽  
Heterocyclic System ◽  
Electronic Absorption Spectra ◽  
Electron Structure ◽  
Ultraviolet Region ◽  
Near Ultraviolet ◽  
Experimental Absorption

The results of the PPP calculations of the singlet-singlet transitions of 1-methyl-3'-cyano-3'-alkoxycarbonyl-2-propenylidene-1,2-dihydropyridines II and 1-methyl-4-amino-3,3'-dicyano-3',5-di(methoxycarbonyl)-2-propenylidene-1,2-dihydropyridine (III) are in a satisfactory agreement with the experimental absorption curves in the visible and near ultraviolet region. Based on this finding, the absorption of the parent heterocyclic system of 2-propenylidene-1,2-dihydropyridine (I) is predicted. Some aspects of the π-electron structure of the substances I-III in the S0, S1 S2 and states are discussed.

Reproduction of the UV-vis spectra of boron subphthalocyanine chloride in different solvents using time-dependent generalized Kohn–Sham density functionals with first solvation shell

2018 ◽  
Vol 22 (08) ◽  
pp. 670-678 ◽  
Author(s):  
Xue Chen ◽  
Wenlan Chen ◽  
Shaohui Zheng
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Solvation Shell ◽  
Photon Absorption ◽  
Ultraviolet Region ◽  
Density Functionals ◽  
Research Fields ◽  
Boron Subphthalocyanine ◽  
Experimental Absorption

Because of the unique physical, chemical and optical characteristics of boron subphthalocyanine chloride, it has been widely applied in different research fields and attracted global researchers. Deep insight into its UV-vis spectrum is required to understand the mechanism of the photon absorption of boron subphthalocyanine chloride in its condensed phase. In the present work, we utilize generalized Kohn–Sham density functionals with a non-equilibrium solvation model to simulate the UV-vis spectra of boron subphthalocyanine chloride in different solvents. Without considering the first solvation shell, we find that the slopes of lines drawn with [Formula: see text]B97XD and CAM-B3LYP results vs. experimental absorption wavelengths are close to 1.0 and root–mean–square deviations are less than 40 nm. We also find that the inclusion of the first solvation shell surrounding boron subphthalocyanine chloride monomers generally makes the calculated results worse. Finally, we discover that the simulated results overestimate oscillator strength of electronic absorption spectra in the ultraviolet region with respect to experimental spectra. These results imply that it may be important to consider the aggregation of solute molecules in order to understand the electronic absorption spectra of subPC in solution

Electronic absorption spectra and dipole moments of diazafluoren-9-ones studied by the MIM, PPP, and CNDO/2 methods

1976 ◽  
Vol 54 (12) ◽  
pp. 1870-1874 ◽  
Author(s):  
Concetta Gandolfo ◽  
Giuseppe Buemi ◽  
Domenico Grasso ◽  
Salvatore Fasone
Keyword(s):  
Absorption Spectra ◽  
Satisfactory Agreement ◽  
Electronic Absorption ◽  
Electronic Spectra ◽  
Benzene Solution ◽  
Electronic Absorption Spectra ◽  
Dipole Moments ◽  
Theoretical Data ◽  
Uv Spectra

The electronic spectra of three diazafluoren-9-one isomers have been measured in cyclohexane solution and the results compared with those of 'molecules in molecules'(MIM) and PPP calculations. A satisfactory agreement between experimental and theoretical data has been found, and five π → π* transitions can be assigned to their uv spectra. For two compounds dipole moments in benzene solution have been measured and results are compared with theoretical values obtained by MIM and CNDO/2 calculations.

Rydberg and valence-shell transitions in the quartz ultraviolet spectra of aliphatic thiones

1981 ◽  
Vol 59 (6) ◽  
pp. 952-956 ◽  
Author(s):  
A. E. Bruno ◽  
D. J. Clouthier ◽  
P. G. Mezey ◽  
R. P. Steer
Keyword(s):  
Gas Phase ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Ultraviolet Region ◽  
Valence Shell ◽  
Ultraviolet Spectra ◽  
Semi Empirical

The electronic absorption spectra of 3,3-dimethylbutane-2-thione and 3-methylbutane-2-thione in the gas phase have been measured and the observed transitions assigned with the aid of abinitio and semi-empirical calculations. In the quartz ultraviolet region four transitions are observed. A strong, broad, structureless band is assigned to the π → π* transition and three weaker, narrower bands are assigned to Rydberg n → 4s, n → 4py and n → 4pz transitions on sulfur.

Electronic Absorption Spectra of Benzylchloride Vapor

1969 ◽  
Vol 23 (6) ◽  
pp. 616-617 ◽  
Author(s):  
R. Ammini Amma ◽  
K. P. R. Nair ◽  
D. K. Rai
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Ultraviolet Absorption ◽  
The Other ◽  
Electronic Transitions ◽  
Near Ultraviolet ◽  
Two Systems ◽  
Quartz Spectrograph

The near-ultraviolet absorption spectra of benzylchloride vapor have been photographed on a medium quartz spectrograph. Two systems of bands have been observed, one at 37 115 cm−1 and the other at 41 748 cm−1, which correspond to B2 ↓ A1 and A1 ↓ A1 electronic transitions. The observed spectra have been analysed in terms of fundamentals and overtones.

Stereochemistry of [carbonato-bis((S)-prolinato)]cobaltate(III) anion

1984 ◽  
Vol 49 (3) ◽  
pp. 680-683 ◽  
Author(s):  
Bohumil Hájek ◽  
Dagmar Sýkorová ◽  
Jiří Chyba
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Cd Spectra

The λ-C1-cis(N), δ-C1-cis(N), λ-C2-cis(N) and δ-C2-cis(N) isomers of the complex K[Co((S)-Pro)2CO3] were chromatographically separated and characterized by their electronic absorption spectra and CD spectra.

Photocolouration of 2,4,4,6-Tetraaryl-4H-pyrans and Their Heteroanalogues: Importance of Hypervalent Photoisomers

1995 ◽  
Vol 60 (10) ◽  
pp. 1621-1633 ◽  
Author(s):  
Stanislav Böhm ◽  
Mojmír Adamec ◽  
Stanislav Nešpůrek ◽  
Josef Kuthan
Keyword(s):  
Reaction Kinetics ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Theoretical Data ◽  
Order Reaction ◽  
Bleaching Process ◽  
First Order ◽  
Photodegradation Products ◽  
Hypervalent Molecules

Molecular geometries of 2,4,4,6-tetraphenyl-4H-pyran (Ia), 4,4-(biphenyl-2,2e-diyl)-2,6-diphenyl-4H-pyran (Ib) and their heterocyclic isomers II-V were optimized by the 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 possible to select hypervalent molecules IIIa, IIIb, IVa and IVb being responsible for the photocolouration of 4H-pyrans Ia, Ib, while compounds Va, Vb, VI and VII come into account as possible photodegradation products. The bleaching process of the UV illuminated compound Ia is analyzed in terms of dispersive first-order reaction kinetics.

Niobocene Dichloride and Niobocene Diiodide: Electronic Absorption Spectra and Electron Spin Resonance

1998 ◽  
Vol 63 (5) ◽  
pp. 628-635 ◽  
Author(s):  
Jana Holubová ◽  
Zdeněk Černošek ◽  
Ivan Pavlík
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Point Group ◽  
Esr Spectra ◽  
Ligand Field ◽  
Orbital Interaction ◽  
Symmetry Point Group ◽  
Spin Orbital ◽  
Halide Ligands

The effect of the halide ligand on the bonding of niobium in niobocene dichloride and niobocene diiodide was investigated. The electronic absorption spectra of the two compounds in the range of d-d transitions were resolved into four bands corresponding to transitions of the d1 electron between five frontier orbitals in a molecule of symmetry point group C2v. The energies of the frontier molecular orbitals were determined relatively to the energy of the orbitals in the spherically symmetric ligand field formed by the appropriate halide ligands. The effect of the halide ligands on the spin-orbital interaction of the HOMO orbital is discussed qualitatively on the basis the ESR spectra.

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