Stabilities, Excitation Energies, and Dissociation Reactions of CF2Cl2and CF2Br2:  Quantum Chemical Computations of Heats of Formation of Fluorinated Methanes, Methyls, and Carbenes

2000 ◽  
Vol 104 (47) ◽  
pp. 11212-11219 ◽  
Author(s):  
Melanie R. Cameron ◽  
George B. Bacskay
Keyword(s):  
Quantum Chemical ◽  
Heats Of Formation ◽  
Excitation Energies ◽  
Quantum Chemical Computations

Heats of Formation of Hydrofluorocarbons Obtained by Gaussian-3 and Related Quantum Chemical Computations

2000 ◽  
Vol 104 (32) ◽  
pp. 7600-7611 ◽  
Author(s):  
Naomi L. Haworth ◽  
Michael H. Smith ◽  
George B. Bacskay ◽  
John C. Mackie
Keyword(s):  
Quantum Chemical ◽  
Heats Of Formation ◽  
Quantum Chemical Computations

scholarly journals Unrevealing mechanism of the thermal tautomerization of avobenzone by means of quantum chemical computations

2016 ◽  
Vol 81 (12) ◽  
pp. 1393-1406 ◽  
Author(s):  
Marko Kojic ◽  
Milena Petkovic ◽  
Mihajlo Etinski
Keyword(s):  
Excited State ◽  
Quantum Chemical ◽  
Electronic Excitation ◽  
Reduced Model ◽  
Additional Insight ◽  
Excitation Energies ◽  
Tert Butyl ◽  
Transient Structures ◽  
Quantum Chemical Computations ◽  
Insight Into

Avobenzone (4-tert-butyl-4?-methoxydibenzoylmethane) is one of the most widely used UVA filters in cosmetic sunscreens. Reactivity of avobenzone is complex and challenging to understand, due to a presence of transient tautomers. In this contribution we study chelated enol, rotamer and keto tautomers of a reduced model of avobenzone which are involved in keto-enol tautomerization. Two thermal tautomerization mechanisms are postulated and their transient structures are discussed. The computed vertical and adiabatic electronic excitation energies of tautomers provide an additional insight into excited state properties of the tautomers.

Silicenium Ions: Quantum Chemical Computations

2009 ◽  
Author(s):  
Christoph Maerker ◽  
Paul von Ragué Schleyer
Keyword(s):  
Quantum Chemical ◽  
Quantum Chemical Computations

scholarly journals Synthesis, quantum chemical computations and x-ray crystallographic studies of a new complex based of manganese (+II)

2017 ◽  
Vol 9 (2) ◽  
pp. 770
Author(s):  
N Benyza ◽  
A Messai ◽  
A Hamdaoui ◽  
T Lanez ◽  
K Sayin
Keyword(s):  
Quantum Chemical ◽  
X Ray ◽  
Quantum Chemical Computations

scholarly journals Standard Molar Enthalpies of Formation of Halomethanes Based on Quantum Chemical Computations

2020 ◽  
Author(s):  
Konstantinos Kalamatianos
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Halogen Bond ◽  
Chemical Processes ◽  
Enthalpies Of Formation ◽  
Isodesmic Reaction ◽  
Gold Standard Method ◽  
Ozone Destruction ◽  
Quantum Chemical Computations ◽  
Reaction Schemes

Accurate calculations of standard molar enthalpies of formation (ΔΗf°)m(g) and carbon-halogen bond dissociation enthalpies, BDE, of a variety of halomethanes with relevance on several atmospheric chemical processes and particularly to ozone destruction, were performed in the gas phase at 298.15 K. The (ΔΗf°)m(g) of the radicals formed through bond dissociations have also been computed. Ab initio computational methods and isodesmic reaction schemes were used. It is found that for the large majority of these species, the gold standard method of quantum chemistry (CCSD(T)) and even MP2 are capable to predict enthalpy values nearing chemical accuracy provided that isodesmic reaction schemes are used. New estimates for standard molar enthalpies of formation and BDE are suggested including for species that to our knowledge there are no experimental (ΔΗf°)m(g) (CHCl2Br, CHBr2Cl, CHBrCl, CHICl, CHIBr) or BDE values (CHCl2Br, CHBr2Cl, CHBrCl, CHICl, CHIBr) available in the literature. The method and calculational procedures presented may profitably be used to obtain accurate (ΔΗf°)m(g) and BDE values for these species.

Excitons in poly(para phenylene vinylene): a quantum-chemical perspective based on high-level ab initio calculations

2016 ◽  
Vol 18 (4) ◽  
pp. 2548-2563 ◽  
Author(s):  
Stefanie A. Mewes ◽  
Jan-Michael Mewes ◽  
Andreas Dreuw ◽  
Felix Plasser
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Quantum Chemical ◽  
Phenylene Vinylene ◽  
High Level ◽  
Quantum Chemical Computations

Exciton analyses of high-level quantum-chemical computations for poly(paraphenylene vinylene) reveal the nature of the excitonic bands in PPV oligomers.

Höhere Triplettanregungszustände von Fluoren, Carbazol und Benzologen: CNDO-CI-Berechnungen und Triplett-Triplett-Absorptionsmessungen

1976 ◽  
Vol 31 (1) ◽  
pp. 84-86 ◽  
Author(s):  
F. Fratev ◽  
H. Hermann ◽  
G. Olbrich ◽  
O. E. Polansky ◽  
M. Zander
Keyword(s):  
Experimental Data ◽  
Chemical Treatment ◽  
Quantum Chemical ◽  
Excitation Energies ◽  
Triplet Excitation ◽  
Absorption Measurements ◽  
Good Agreement ◽  
Triplet Absorption

CNDO-Cl calculations of triplet-triplet excitation energies on fluorene, carbazole and their monobenzologues are in good agreement with the results from triplet-triplet absorption measurements. An assignment of the observed triplet data is given. It is shown that the quantum-chemical treatment should be useful in cases where the experimental data are difficult to obtain.

Insights into the Recognition of Phosphate Groups by Peptidic Arginine from Action Spectroscopy and Quantum Chemical Computations

2019 ◽  
Author(s):  
Juan Ramon Aviles-Moreno ◽  
Giel Berden ◽  
Jos Oomens ◽  
Bruno Martínez-Haya
Keyword(s):  
Quantum Chemical ◽  
Action Spectroscopy ◽  
Quantum Chemical Computations ◽  
Phosphate Groups

Methylamination of some 3,6-dinitro-1,8-naphthyridines with liquid methylamine – potassium permanganate

2000 ◽  
Vol 78 (7) ◽  
pp. 950-956
Author(s):  
Marian Wozniak ◽  
Maria Grzegozek ◽  
Piotr Surylo
Keyword(s):  
Quantum Chemical Calculations ◽  
Potassium Permanganate ◽  
Satisfactory Agreement ◽  
Quantum Chemical ◽  
Transition States ◽  
Molecular Orbitals ◽  
Heats Of Formation ◽  
Convenient Synthesis

3,6-Dinitro-1,8-naphthyridine and its 2-substituted derivatives are dehydro-methylaminated with the solution of potassium permanganate in liquid methylamine (LMA–PP) to the corresponding mono- or mono- and bis(methylamino)-3,6-dinitro-1,8-naphthyridines. In the case of 2-chloro- and 2-methoxy-3,6-dinitro-1,8-naphthyridine the replacement of chloro and methoxy substituents by the NHCH3 group occurs as well. Quantum-chemical calculations indicate the reactions to be controlled by the interaction of the frontal molecular orbitals (FMO) of the reagents. Moreover the heats of formation of intermediary methylamino-σ-adducts and transition states are calculated for the reaction studied. The calculations show satisfactory agreement between calculated and observed results. A convenient synthesis of some 2-substituted-3,6-dinitro-1,8-naphthyridines is reported.Key words: methylaminations, calculations PM3, nitro-1,8-naphthyridines, oxidation.

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