Optimized ladder C and ladder H models for sigma conjugation: chain segmentation in polysilanes

2002 ◽  
Vol 15 (8) ◽  
pp. 490-498 ◽  
Author(s):  
Thorsten Schepers ◽  
Josef Michl
Keyword(s):  
Conjugation Chain

Correlation of the π-conjugation chain length and the property and photovoltaic performance of benzo[1,2-b:4,5-b′]dithiophene-cored A-π-D-π-A type molecules

2016 ◽  
Vol 157 ◽  
pp. 831-843 ◽  
Author(s):  
Lilei Wang ◽  
Ying Zhang ◽  
Ni Yin ◽  
Yi Lin ◽  
Wei Gao ◽  
...  
Keyword(s):  
Chain Length ◽  
Photovoltaic Performance ◽  
Conjugation Chain

Circularly polarized luminescence based chirality transfer of the chiral BINOL moiety via rigid π-conjugation chain backbone structures

2017 ◽  
Vol 8 (9) ◽  
pp. 1555-1561 ◽  
Author(s):  
Fandian Meng ◽  
Yunzhi Li ◽  
Wenjie Zhang ◽  
Shuhua Li ◽  
Yiwu Quan ◽  
...  
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Chirality Transfer ◽  
Circularly Polarized ◽  
Cross Coupling Reaction ◽  
Conjugation Chain ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence

Three kinds of chiral BINOL-based polymers could be synthesized by polymerization in a Pd-catalyzed cross-coupling reaction.

Syntheses and Second-Order Optical Nonlinearity of Ruthenium σ-Acetylides with an End-Capping Organic Electron Acceptor and Thienyl Entity in the Conjugation Chain

1998 ◽  
Vol 17 (11) ◽  
pp. 2188-2198 ◽  
Author(s):  
Iuan-Yuan Wu ◽  
Jiann T. Lin ◽  
Jimmy Luo ◽  
Chyi-Shiun Li ◽  
Chiitang Tsai ◽  
...  
Keyword(s):  
Electron Acceptor ◽  
Optical Nonlinearity ◽  
Second Order ◽  
Conjugation Chain ◽  
Organic Electron ◽  
End Capping

Synthesis, spectroscopy and structure of new push–pull ferrocene complexes containing heteroaromatic rings (thiophene and furan) in the conjugation chain

1999 ◽  
Vol 575 (2) ◽  
pp. 301-309 ◽  
Author(s):  
K.R.Justin Thomas ◽  
Jiann T Lin ◽  
Yuh S Wen
Keyword(s):  
Conjugation Chain

ChemInform Abstract: CHEMISTRY OF UNSATURATED ETHERS. XXXVII. SYNTHESIS OF 1-ALKOXY-1,3-DIENES CONTAINING CYCLIC FRAGMENTS IN THE CONJUGATION CHAIN

1976 ◽  
Vol 7 (47) ◽  
pp. no-no
Author(s):  
S. M. MAKIN ◽  
T. N. BOIKO ◽  
I. I. BOIKO ◽  
O. A. SHAVRYGINA ◽  
M. I. BEREZHNAYA
Keyword(s):  
Conjugation Chain

scholarly journals Synthesis, optical and electrochemical study of bipolar heterocyclic systems, including 1,2,4-oxadiazole moiety

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
D. G. Selivanova ◽  
O. A. Mayorova ◽  
A. A. Gorbunov ◽  
A. N. Vasyanin ◽  
M. V. Dmitriev ◽  
...  
Keyword(s):  
Excited States ◽  
Density Functional ◽  
Time Dependent ◽  
Electrochemical Studies ◽  
Absorption Data ◽  
Functional Theory ◽  
Conjugation Chain ◽  
Td Dft ◽  
Triplet Excited States ◽  
New Compounds

AbstractTwo new 3,5-dihetarylsubstituted 1,2,4- oxadiazoles 8 a,b, including N-alkyl substituted carbazole and thiophene moieties, were synthesized as potential components of materials for organic electronics devices. Optical and electrochemical properties of all new compounds were investigated. On the basis of the experimental UV absorption data, the values of bandgap energies equal to 3.44 eV (8a) and 3.05 eV (8b) were determined. The values of their ionization potentials, HOMO levels (−5.62 eV for 8a, −5.46 eV – for 8b), as well as their electron affinity levels, LUMO levels (−2.2 eV for 8a, −2.4 eV – for 8b), were calculated from the results of electrochemical studies. The energy of the triplet excited states of 8 a,b was defined with the help of time-dependent density functional theory (TD-DFT), comprising 2.68 eV (8a) and 2.32 eV (8b), where the greatest value of this parameter was for the compound with a shorter conjugation chain.

scholarly journals USING QUANTUM-CHEMICAL PARAMETERS FOR PREDICTING ANTIRADICAL (HO•) ACTIVITY OF RELATED STRUCTURES CONTAINING A CINNAMOIL FRAGMENT. IV. STRUCTURE-ACTIVITY RELATIONSHIP BETWEEN UNSATURATION INDICES AND FLAVONE DERIVATIVES WITH FLOROGLUCIN RING “A”

2021 ◽  
Vol 9 (2) ◽  
pp. 161-169
Author(s):  
E. T. Oganesyan ◽  
S. S. Shatokhin
Keyword(s):  
Electron Density ◽  
Quantum Chemical ◽  
Multiple Bond ◽  
Mulliken Charge ◽  
Simultaneous Increase ◽  
Free Valence ◽  
Chemical Parameters ◽  
Quantum Chemical Parameters ◽  
Conjugation Chain ◽  
Vinyl Group

The quantum-chemical parameters of 52 derivatives related to flavanones, flavanonoles, flavones and flavonoles with a phloroglucinic type of the A ring and containing electron-donating substituents in the B ring were studied.The aim is the analysis of the dynamics of changes in the electron density, bond numbers, free valence indices and unsaturation indices on carbon atoms C-7 → C-8 of the vinyl group of the main conjugation chain in relation to the position and number of substituents in the “B” ring and the type of the pharmacological activity.Materials and methods. The quantum-chemical parameters of the 4 analyzed groups of the compounds, have been calculated by the semi-empirical method PM7 (WinMopac 2016 program) on the workstation with an Intel Xeon E5-1620 3.5 GHz processor, 20 GB of RAM.Results and discussion. When comparing the quantum chemical parameters of the analyzed compounds, it was established that when the C-7 → C-8 multiple bond is formed, the free valency and unsaturation indices increase on both carbon atoms of the vinylene group in flavones and flavonols compared to the corresponding flavanones and flavanonols. This is explained by the fact that the value of the bond numbers Nµ on these atoms, on the contrary, decreases (Fµ = 4.732-Nµ). The transition from flavanone to flavone is accompanied by the formation of a vinyl group C-7 → C-8, and therefore both atoms from the sp3-hybridized state go into the sp2-state. The consequence of this transformation is a change in the electronegativity value and an increase in the unsaturation index of C-7 and C-8 atoms: C sp3 = 2.5;  Csp2 = 2.8. At the same time, the transition from flavanone to flavone leads to the formation of a conjugated system with the participation of π-electrons of the aromatic system “B”, C-7, C-8 atoms and the carbonyl group, which is commonly called the “main conjugation chain”. These structural changes, namely, the transition from a less oxidized flavanone to a more oxidized flavone, contribute to a decrease in the electron density on C-7 and C-8 atoms, and an increase in the total unsaturation of the molecules in general. Mulliken charges on C-7 of all groups of compounds are characterized by a positive value. As for the carbon atoms of the B fragment, the following features are revealed here: in the presence of one substituent -OH or -OCH3 on the carbon atom to which the substituent is bounded, the Mulliken charge is positive; if there are two substituents in the B ring -OH or -OCH3, as well as two -OCH3 groups, then the carbon atoms bonded to the indicated substituents also have a positive Mulliken charge; in the case of trihydroxy substituted in the C-2, C-3 and C-4 B ring, all three carbon atoms are characterized by a positive Mulliken charge; if there are methoxy groups in positions C-2, C-3 and C-4, then the positive Mulliken charge is concentrated only on C-2 and C-4 atoms, and on C-3 atom this charge has a negative value.Conclusion. The above data on the quantum-chemical parameters of the main conjugation chain indicate that the transition of C-7 and C-8 atoms to the sp2-hybrid state, leads to a decrease in the electron density and a decrease in the bond numbers, with a simultaneous increase in the indices of unsaturation and free valence on these atoms. Thus, the trigger mechanism of the anti-radical activity, primarily with respect to the HO • radical, is determined by the fact that this particle, electrophilic in its properties, will attach in the C-8  atom during an initial attack. 

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