Study of the azo-hydrazone tautomeric equilibrium by electronic spectroscopy and quantum chemistry. II. HMO calculations

1988 ◽  
Vol 53 (2) ◽  
pp. 227-242 ◽  
Author(s):  
Miloš Titz ◽  
Miloš Nepraš ◽  
Miroslav Nečas ◽  
Radim Hrdina ◽  
Stanislav Luňák ◽  
...  
Keyword(s):  
Experimental Data ◽  
Quantum Chemistry ◽  
Quantum Chemical ◽  
Chemical Method ◽  
Electronic Spectroscopy ◽  
Tautomeric Equilibrium ◽  
Quantum Chemical Method ◽  
Fused Ring ◽  
Amino Derivatives ◽  
Derivatives Of

Experimental data obtained in Part I of this work for p-hydroxy and p-amino derivatives of four arylazo compounds with different fused ring systems were correlated with some indices calculated by the simple HMO quantum chemical method in relation to the π-electron structure of the azo and hydrazone tautomers of the compounds studied. Mental fragmentation and the related stability of the systems expressed by Julg’s aromaticity indices of the hydrocarbon fragments appeared to be basically different for the two tautomers.

Study of the azo-hydrazone tautomeric equilibrium by electronic spectroscopy and quantum chemistry. I. Electronic spectra

1988 ◽  
Vol 53 (2) ◽  
pp. 213-226 ◽  
Author(s):  
Miloš Nepraš ◽  
Miloš Titz ◽  
Miroslav Nečas ◽  
Stanislav Luňák ◽  
Radim Hrdina ◽  
...  
Keyword(s):  
Electronic Spectra ◽  
Low Temperatures ◽  
Electronic Spectroscopy ◽  
Tautomeric Equilibrium ◽  
Proton Donor ◽  
Ring Fusion ◽  
And Topology ◽  
Amino Derivatives ◽  
Spectral Patterns ◽  
Derivatives Of

The azo-hydrazone tautomeric equilibrium was studied for p-hydroxy and p-amino derivatives of some arylazo compounds. Substantial differences were observed between the spectral patterns in hydrocarbon and alcoholic solutions at normal and low temperatures; these are due to shifts in the azo-hydrazone tautomeric equilibrium, which depends on the nature of the proton donor para substituent, size and topology of the system (aromatic ring fusion patterns), solvent and temperature. The spectral patterns suggest that the proton transfer from the para substituent takes place after dimerization of the molecule.

Study of Substituted Formylchromones

1994 ◽  
Vol 59 (7) ◽  
pp. 1673-1681 ◽  
Author(s):  
Hafez M. El-Shaaer ◽  
Pavol Zahradník ◽  
Margita Lácová ◽  
Mária Matulová
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Chemical ◽  
Chemical Method ◽  
Electron Distribution ◽  
Chemical Shifts ◽  
Aromatic Nucleus ◽  
Quantum Chemical Method ◽  
Pyrone Ring ◽  
H Nmr ◽  
Derivatives Of

Substituted derivatives of 2- and 3-formylchromone were synthesized and studied by IR, 13C and 1H NMR spectroscopy and the AM1 quantum chemical method. Energy and electron distribution calculations confirm the preference of the synplanar conformation in 3-formylchromones. The calculated charges on the carbon atoms correlate well with the experimental 13C chemical shifts. Substituents bonded to the aromatic nucleus have only small effect on the electron structure of the pyrone ring.

Solvation of ions by dipolar aprotic solvents and water. A CNDO/2 study

1985 ◽  
Vol 50 (11) ◽  
pp. 2493-2508 ◽  
Author(s):  
Petr Kyselka ◽  
Zdeněk Havlas ◽  
Ivo Sláma
Keyword(s):  
Binary Mixtures ◽  
Quantum Chemical ◽  
Chemical Method ◽  
Molecular Structures ◽  
Dimethyl Sulphoxide ◽  
Ternary Mixtures ◽  
Aprotic Solvents ◽  
Quantum Chemical Method ◽  
Solvation Of Ions ◽  
Dipolar Aprotic Solvents

Solvation of Li+, Be2+, Na+, Mg2+, and Al3+ ions has been studied in binary mixtures with dimethyl sulphoxide, dimethylformamide, acetonitrile and water, and in ternary mixtures of the organic solvents with water. The CNDO/2 quantum chemical method was used to calculate the energies of solvation, molecular structures and charge distributions for the complexes acetonitrile...ion (1:1, 2:1, 4:1), dimethyl sulphoxide...ion (1:1), dimethylformamide...ion (1:1), and acetonitrile (dimethyl sulphoxide, dimethylformamide)...ion...water (1:1:1).

The optoelectronic properties of π-conjugated organic molecules based on terphenyl and pyrrole for BHJ solar cells: DFT / TD-DFT theoretical study

2021 ◽  
Vol 10 (4) ◽  
pp. 489-502 ◽  
Author(s):  
M. Raftani ◽  
T. Abram ◽  
W. Loued ◽  
R. Kacimi ◽  
A. Azaid ◽  
...  
Keyword(s):  
Solar Cells ◽  
Quantum Chemical ◽  
Chemical Method ◽  
Chemical Reactivity ◽  
Optoelectronic Properties ◽  
Oscillator Strengths ◽  
Frontier Molecular Orbital ◽  
Bandgap Energy ◽  
Quantum Chemical Method ◽  
Td Dft

In the present paper, four π-conjugated materials, based on terphenyl and pyrrole, with A–D–A structure have been theoretically studied to propose new organic compounds to be used in the organic solar cell field. Moreover, the geometrical and optoelectronic properties of the designed molecules M1, M2, M3 and M4 have been computed after optimization in their fundamental states, using the quantum chemical method DFT / B3LYP/ 6−311G (d, p). Different parameters including HOMO and LUMO energy levels, bandgap energy, frontier molecular orbital (FMO), chemical reactivity indices, the density of states (DOS), Voc, electrostatic potential (ESP), and thermodynamic parameters at several temperatures in the range of 0-500 K have been determined. The absorption properties including the transition energy, the wavelengths (λmax), the excitation vertical energy, and the corresponding oscillator strengths of these molecules have been studied using the quantum chemical method TD−DFT / CAM–B3LYP / 6–311G (d, p). The obtained results of our studied compounds show that M3 (with 2H, 2'H-1, 1'-biisoindole moiety) as a donor group has special optoelectronic, absorption, and good photovoltaic characteristics. Thus, they can be utilized as an electron-donating in organic solar cells BHJ type.

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