Unusually Large Coupling Constants in Diradicals Obtained from Excitation of Mixed Radical Centers: A Theoretical Study on Potential Photomagnets

2010 ◽  
Vol 114 (24) ◽  
pp. 6701-6704 ◽  
Author(s):  
Ujjal Bhattacharjee ◽  
Anirban Panda ◽  
Iqbal A. Latif ◽  
Sambhu N. Datta
Keyword(s):  
Theoretical Study ◽  
Coupling Constants ◽  
Large Coupling

A theoretical study of multinuclear coupling constants in pyrazoles

2005 ◽  
Vol 43 (12) ◽  
pp. 985-991 ◽  
Author(s):  
Rosa M. Claramunt ◽  
Dionisia Sanz ◽  
Ibon Alkorta ◽  
José Elguero
Keyword(s):  
Theoretical Study ◽  
Coupling Constants

scholarly journals Fermions on wobbling kinks: normal versus quasinormal modes

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
João G. F. Campos ◽  
Azadeh Mohammadi
Keyword(s):  
Transition Probabilities ◽  
Transition Probability ◽  
Quasinormal Modes ◽  
Golden Rule ◽  
Coupling Constants ◽  
Large Coupling ◽  
Constant Rate ◽  
Fermi's Golden Rule ◽  
The Impact ◽  
Fermi’S Golden Rule

Abstract The system consisting of a fermion in the background of a wobbling kink is studied in this paper. To investigate the impact of the wobbling on the fermion-kink interaction, we employ the time-dependent perturbation theory formalism in quantum mechanics. To do so, we compute the transition probabilities between states given in terms of the Bogoliubov coefficients. We derive Fermi’s golden rule for the model, which allows the transition to the continuum at a constant rate if the fermion-kink coupling constant is smaller than the wobbling frequency. Moreover, we study the system replacing the shape mode with a quasinormal mode. In this case, the transition rate to continuum decays in time due to the leakage of the mode, and the final transition probability decreases sharply for large coupling constants in a way that is analogous to Fermi’s golden rule. Throughout the paper, we compare the perturbative results with numerical simulations and show that they are in good agreement.

Experimental and Theoretical-Study of Carbon-Fluorine Couplings in the NMR-Spectra of 2-Fluoroaryl Ketones

1985 ◽  
Vol 38 (12) ◽  
pp. 1779 ◽  
Author(s):  
RH Contreras ◽  
CG Giribet ◽  
MA Natiello ◽  
J Perez ◽  
ID Rae ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Side Chain ◽  
Aliphatic Carbon ◽  
Spin Coupling Constants ◽  
Fermi Contact ◽  
Spin Spin Coupling ◽  
Fermi Contact Term ◽  
Good Agreement

Calculations by the IPPP-INDO method give the spin-spin coupling constants for the side-chain carbons, 3JCF and 4JCF, as 4.97 and 6.86 Hz respectively with substantial contributions to through-space coupling from the pathway CO-C-H…F. The observed values for 1-(2- fluorophenyl ) ethanone , 3.3 and 7.2 Hz, and for 1-(2,5- difluorophenyl ) ethanone , 3.7 and 7.3 Hz, are in good agreement with these predictions. Two compounds, a dihydroindenone and a naphthalenone, in which this pathway cannot be effective, show no fluorine coupling to the aliphatic carbon next to the carbonyl and the values of 3JCF are reduced to 2.2 and 2.5 Hz, consistent with the loss of a through-space Fermi contact term of the kind described above.

Neue Untersuchung über Inhaltsstoffe aus Aloe-und Rhamnus-Arten, XV [1] Homonataloin A und B aus Aloe lateritia: Reindarstellung, Konstitutions-und Konfigurationsaufklärung der Diastereomeren / A New Investigation on Constituents of Aloe and Rhamnus Species, XV [1] Hom onataloins A and B from Aloe lateritia: Isolation, Structure and Configurational Determ ination of the Diastereomers

1991 ◽  
Vol 46 (3-4) ◽  
pp. 177-182 ◽  
Author(s):  
Hans-W. Rauwald ◽  
Deo-D. Niyonzima
Keyword(s):  
Chemical Shifts ◽  
Optical Rotation ◽  
Coupling Constants ◽  
Cd Spectra ◽  
Large Coupling ◽  
H Nmr ◽  
Leaf Exudate ◽  
Hydroxyl Protons ◽  
Nmr Signals ◽  
C Nmr

From the leaf exudate of Aloe lateritia ENGLER the C-glucosyl com pounds homonataloin, aloeresin A and aloesin (synon. aloeresin B) were isolated together with the anthraquinone nataloeem odin-8-methylether and spectroscopically identified. Hom onataloin, widely distributed in Aloe species, was separated into homonataloin A and B by combined TLC and DCCC. In their 1 D and 2D 1H NMR spectra only the shifts of the 2′-hydroxyl protons of both glucosyl residues differ significantly, indicative of 10 S (A) resp. 10 S (B) configurations. In both com pounds the anthrone is in β-position of the D-glucopyranosyl, as determined by the large coupling constants of the anomeric protons. The 13C NMR signals are unambiguously assigned by the use of DEPT, APT and gated-decoupling methods. Only the chemical shifts of C -11 and C -14 show significant differences between both diastereomers due to the adjacent 2′-sugar hydroxyls. The two homonataloins differ mostly in optical rotation and circulardichroism due to different configurations at C - 10 of the anthrone part. The absolute configurations of the diastereomers are determined by correlation of their CD spectra with the CD spectra of the structural analogues 7-hydroxyaloins A and B, which shows that hom onataloin A is the 10 S, 1′S-compound and that homonataloin B has 10 R, 1′S-configuration.

scholarly journals One-bond 1 J (15 N,H) coupling constants at sp2 -hybridized nitrogen of Schiff bases, enaminones and similar compounds: A theoretical study

2020 ◽  
Vol 58 (8) ◽  
pp. 750-762
Author(s):  
Poul Erik Hansen ◽  
Bahjat A. Saeed ◽  
Rita S. Rutu ◽  
Teobald Kupka
Keyword(s):  
Schiff Bases ◽  
Theoretical Study ◽  
Coupling Constants
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