Acceptor/Donor End Capped Phenylene-Thiophene Co-oligomers Toward Efficiencies Organic Electronic Devices
Abdelkader Hlel,
Saber Ghomrasni,
Walid Taouali,
Kamel Alimi
Issue:
Volume 8, Issue 1, June 2020
Pages:
1-10
Received:
11 November 2019
Accepted:
3 December 2019
Published:
4 January 2020
Abstract: In this paper, geometrical (in ground and excited states), electronic, optical and charge transfer properties, (ionization potentials (IP), electron affinities (EA) and HOMO-LUMO gaps (ΔEH-L), as well as the lowest excitation energies (Eex) and reorganization energies) of the phenylene-tiophene oligomers are studied by the density functional theory (DFT) and Time-dependent DFT approaches. Based on the density functional theory (DFT/B3LYP and CAM –B3LYP functional with 6-31G (d,p) basis set), we will highlight the effect of terminal acceptor/donor (CN, NO2, and CF3) /OCH3, N(CH3)2 substituents on thiophene-phenylene derivatives. The excited state indicates more planar structures of the co-oligomers, which leads to a decrease in the (HOMO-LUMO) gap compared with the ground state, especially when the acceptor character increases. Furthermore, the vinyl spacer and cyanide ((–CN) functional group (Compound C8) stabilize the LUMO levels of energy and improve the transport properties of the thiophene-phenylene derivatives. Comparing with the donor groups, the results show that the electron withdrawing substituents are remarkable on the energy levels of the frontier molecular orbitals, and on the transport charge proprieties in these co-oligomers. Thus, the LUMO energy levels become more stabilized for co-oligomers having more acceptor moieties and the HOMO–LUMO energy gap is reduced, therefore, the improvement of the conduction properties of these species is, then, observed. Moreover, the absorption spectra, computed in the presence or not of solvent at PCM model in chloroform, shows that the increase of acceptor character induces a red shift and important absorption intensity. The decrease injection barrier and smaller reorganization energies are revealing that our designed co-oligomers would be an efficient hole as well as electron transfer materials. The predicted values have shown that the designed derivatives would be efficient for the organic field effect transistors, photovoltaics and light emitters.
Abstract: In this paper, geometrical (in ground and excited states), electronic, optical and charge transfer properties, (ionization potentials (IP), electron affinities (EA) and HOMO-LUMO gaps (ΔEH-L), as well as the lowest excitation energies (Eex) and reorganization energies) of the phenylene-tiophene oligomers are studied by the density functional theory...
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Importance of Hydride-Hydride Interaction in the Stabilization of LiH, NaH, KH, LiAlH4, NaAlH4, and Li3AlH6 as Solid-State Systems for Hydrogen Storage
James Tembei Titah,
Franklin Che Ngwa,
Mamadou Guy-Richard Kone
Issue:
Volume 8, Issue 1, June 2020
Pages:
11-18
Received:
11 December 2019
Accepted:
24 December 2019
Published:
7 January 2020
Abstract: The solid-state structures of LiH, NaH, KH, LiAlH4, NaAlH4 and Li3AlH6 have been explored in details as potential hydrogen-storage materials using computational electron density methods; the full-potential linearized augmented plane wave (FPLAPW) method plus local orbital (FPLAPW+lo) embodied in the WIEN2k package code. Topological analysis of their DFT-computed electron densities in tandem with Bader’s Atoms in Molecules (AIM) theory reveals a plethora of stabilizing interactions some of which are really strong. With the exception of NaH and KH, which do not contain the hydride-hydride bonding, the rest of the metal hydrides; LiH, LiAlH4, NaAlH4 and Li3AlH6 show an increasing number of hydride-hydride interactions that contribute to the stabilization of their three-dimensional (3-D) solid-state structures. Even though these hydride-hydride interactions are weaker compared to the M-H counterparts, their multiplicity greatly contributes to the stability of these metal hydrides. Results from their electron density studies reveal that the number of hydride-hydride interactions in these binary and complex metal hydrides increase with the complexity of the solid-state structures. LiAlH4 is more stable compared to NaAlH4, Li3AlH6, and LiH. NaH and KH were seen to be the least stable solid-state structures. It is suggested that the presence of these hydride-hydride interactions play a significant role in the mediation or understanding of the reaction mechanism leading to the release of hydrogen from these solid-state systems.
Abstract: The solid-state structures of LiH, NaH, KH, LiAlH4, NaAlH4 and Li3AlH6 have been explored in details as potential hydrogen-storage materials using computational electron density methods; the full-potential linearized augmented plane wave (FPLAPW) method plus local orbital (FPLAPW+lo) embodied in the WIEN2k package code. Topological analysis of thei...
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Molecular Dynamics Simulation of Human Pancreatic Lipase and Lipase-colipase Complex: Insight into the Structural Fluctuations and Conformational Changes
Sikiru Akinyeye Ahmed,
Nizakat Ali,
Urooj Qureshi,
Ruqaiya Khalil,
Zaheer-Ul Haq Qasmi
Issue:
Volume 8, Issue 1, June 2020
Pages:
19-26
Received:
25 January 2020
Accepted:
17 February 2020
Published:
28 February 2020
Abstract: Although the structure of Human Pancreatic Lipase has been documented through the X-ray crystallography, the knowledge about the molecular rearrangement and dynamic equilibrium in the structure (particularly in the catalytic triad and lid domains) is very scanty. The structural fluctuations and conformational changes undergo by Human Pancreatic Lipase (HPL) with and without colipase were computationally investigated through molecular dynamics simulation technique using GROMACS 2018.4, MOE 2016.0801 and VMD softwares in order to gain insight into the complex transitions at different domains. The structural stability was revealed vis-a-vis Root Mean Square Deviation (RMSD) and Root Mean Square Fluctuations (RMSF) plots. The levels of compactness/folding and conformational changes of the protein were determined using Radius of gyration and secondary analysis respectively. Salt bridge analysis gives more ionic pairs interactions than experimentally determined results. Results show that though both proteins are stable, lipase-colipase complex is more deviated and flexible than lipase. Also, additional information regarding the conformational transitions, interactions and dynamics that govern stability of lipase-colipase complex which were ‘hidden’ to experimental techniques were revealed.
Abstract: Although the structure of Human Pancreatic Lipase has been documented through the X-ray crystallography, the knowledge about the molecular rearrangement and dynamic equilibrium in the structure (particularly in the catalytic triad and lid domains) is very scanty. The structural fluctuations and conformational changes undergo by Human Pancreatic Lip...
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