Semi Empirical Study of a System Containing a Six-membered Ring

2004 ◽  
Vol 59 (11) ◽  
pp. 853-856
Author(s):  
H. Kara ◽  
Y. Yahsi ◽  
Y. Elerman ◽  
A. Elmali
Keyword(s):  
Chemical Potential ◽  
Chair Conformation ◽  
Membered Ring ◽  
Chemical Hardness ◽  
Mo Calculations ◽  
Lumo Energy ◽  
Conformational Interconversion ◽  
Homo And Lumo ◽  
Semi Empirical ◽  
Homo And Lumo Energy

Semi-empirical AM1 SCF-MO calculations have been used to find the structure optimization and conformational interconversion pathways of a system containing a six-membered ring. The system has the two symmetrical energy-minimum conformations, chair and twist. The chair conformation has the most stable geometry. Some quantum parameters such as HOMO and LUMO energy, the chemical hardness and chemical potential are discussed

scholarly journals Synthesis and Characterisation of Novel Thiophene Based Azomethine Polymers and Study of Their Liquid Crystalline, Electrochemical and Optoelectronic Properties

2017 ◽  
Vol 25 (5) ◽  
pp. 345-362 ◽  
Author(s):  
Omer Yasin Al-Janabi ◽  
Peter J.S. Foot ◽  
Emaad Taha Al-Tikrity ◽  
Peter Spearman
Keyword(s):  
Cyclic Voltammetry ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Energy Levels ◽  
Band Gaps ◽  
Gas Liquid Chromatography ◽  
Lumo Energy ◽  
Chemical Structures ◽  
Homo And Lumo ◽  
Homo And Lumo Energy

This work reports the synthesis, structural characterisation, liquid crystallinity, luminescence and electroluminescence of novel thiophene azomethine polymers. The polymers under study were prepared via oxidative polymerisation of four novel monomers at room temperature using iron (III) chloride. The chemical structures of the prepared monomers and polymers were confirmed by infrared and 1H and 13CNMR spectroscopy. Molecular masses were determined for monomers and polymers by gas/liquid chromatography-mass spectrometry (GC/LC-MS) and by gel-permeation (size exclusion) chromatography (SEC), respectively. Thermal stability studies of the prepared materials were achieved by thermogravimetric analysis (TGA), and the onset of weight loss To and the endset Tmax were calculated from the thermograms. Liquid crystalline mesophases and phase changes of the monomers and polymers were studied by differential scanning calorimetry (DSC) and polarised optical microscopy (POM), and the glass transition temperatures Tg of the polymers were determined from the DSC curves. The electrochemical band gaps, HOMO and LUMO energy levels were measured by cyclic voltammetry. UV-visible absorption-emission spectra (liquid and solid films) of the polymers were obtained at room temperature with different solvents. Optical band gaps were calculated from the absorption edges, and were in good agreement with those estimated from cyclic voltammetry. Mixing the polymers with lanthanide salts such as EuCl3 and YbCl3 gave modified fluorescence, and the light emitted was much more intense than that from the pure polymers. Polymer based light-emitting diodes (PLEDs) were fabricated by spin coating, and their current-voltage characteristics were measured. In preliminary work, the polymer devices were found to produce electroluminescent spectra similar to the PL spectra of the corresponding samples. Molecular modelling studies were performed both on polymer segments and monomer molecules; the absorption spectra of the prepared polymers, HOMO and LUMO energy levels were calculated with ZINDO using AMI geometry optimisation.

scholarly journals Synthesis of Novel Derivatives of Carbazole-Thiophene, Their Electronic Properties, and Computational Studies

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
E. F. Damit ◽  
N. Nordin ◽  
A. Ariffin ◽  
K. Sulaiman
Keyword(s):  
Electronic Properties ◽  
Theoretical Calculations ◽  
Energy Levels ◽  
Phenyl Group ◽  
Cyclic Voltammogram ◽  
Coupling Reactions ◽  
Lumo Energy ◽  
Homo And Lumo ◽  
Derivatives Of ◽  
Homo And Lumo Energy

A series of carbazole-thiophene dimers,P1–P9, were synthesized using Suzuki-Miyaura and Ullmann coupling reactions. InP1–P9, carbazole-thiophenes were linked at the N-9 position for different core groups via biphenyl, dimethylbiphenyl, and phenyl. Electronic properties were evaluated by UV-Vis, cyclic voltammogram, and theoretical calculations. Particularly, the effects of conjugation connectivity on photophysical and electrochemical properties, as well as the correlation between carbazole-thiophene and the core, were studied. Carbazole connecting with thiophenes at the 3,6-positions and the phenyl group as a core group leads to increased stabilization of HOMO and LUMO energy levels where the bandgap (ΔE) is significantly reduced.

scholarly journals Spectra and Charge Transport of Polar Molecular Photoactive Layers Used for Solar Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yuanzuo Li ◽  
Dawei Qi ◽  
Chaofan Sun ◽  
Meiyu Zhao
Keyword(s):  
Electric Field ◽  
Charge Transport ◽  
Absorption Spectra ◽  
Energy Levels ◽  
Band Gaps ◽  
Side Chain ◽  
Electron Affinities ◽  
Lumo Energy ◽  
Homo And Lumo ◽  
Homo And Lumo Energy

The ground state structures, HOMO and LUMO energy levels, band gapsΔH-L, ionization potentials (IP), and electron affinities (EA) of three types of copolymer P1 and its derivatives P2, P3, and PBDT-BTA were investigated by using density functional theory (DFT) with B3LYP and 6-31G (d) basis set. On the base of optimized structures of ground states, their absorption spectra were obtained by using TD-DFT//Cam-B3LYP/6-31 G (d). Research shows that with the increasing conjugated units, HOMO energy levels increased, LUMO energy levels decreased, and band gaps decreased gradually. Moreover, their ionization potentials decreased and electron affinities increased along with the increase of conjugated chains, and absorption spectra red-shifted. In addition, the side chain has a significant effect on the properties of ground and excited states. In order to investigate the influence of conjugated units and side chain on the charge transport, their hole and electron reorganization energies were calculated, and the results indicated that Pb have a good hole transport capability. Considering the practical application, the HOMO and LUMO energy levels, band gaps, and absorption spectra under external electric field were studied, and the results proved that the external electric field has an effect on the optical and electronic properties.

Experimentally Validated Model for the Prediction of the HOMO and LUMO Energy Levels of Boronsubphthalocyanines

2011 ◽  
Vol 115 (23) ◽  
pp. 11709-11718 ◽  
Author(s):  
Graham E. Morse ◽  
Michael G. Helander ◽  
Jason Stanwick ◽  
Jennifer M. Sauks ◽  
Andrew S. Paton ◽  
...  
Keyword(s):  
Energy Levels ◽  
Lumo Energy ◽  
Homo And Lumo ◽  
Homo And Lumo Energy
Sign in / Sign up

Export Citation Format

Share Document