Novel six organic donor-π-acceptor molecules (D-π-A) used for Bulk Heterojunction organic solar cells (BHJ), based on thienopyrazine were studied by density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches, to shed light on how the π-conjugation order influence the performance of the solar cells. The electron acceptor group was 2-cyanoacrylic for all compounds, whereas the electron donor unit was varied and the influence was investigated. The TD-DFT method, combined with a hybrid exchange-correlation functional using the Coulomb-attenuating method (CAM-B3LYP) in conjunction with a polarizable continuum model of salvation (PCM) together with a 6-31G(d,p) basis set, was used to predict the excitation energies, the absorption and the emission spectra of all molecules. The trend of the calculated HOMO–LUMO gaps nicely compares with the spectral data. In addition, the estimated values of the open-circuit photovoltage (V_oc) for these compounds were presented in two cases/PC₆₀BM and/PC₇₁BM. The study of structural, electronics and optical properties for these compounds could help to design more efficient functional photovoltaic organic materials.

A series of new heterocycle hybrids incorporating pyrazole and isoxazoline rings was successfully synthesized, characterized, and evaluated for their antimicrobial responses. The synthesized compounds were obtained utilizing N-alkylation and 1,3-dipolar cycloaddition reactions, as well as their structures were established through spectroscopic methods and confirmed by mass spectrometry. To get more light on the regioselective synthesis of new hybrid compounds, mechanistic studies were performed using DFT calculations with B3LYP/6-31G(d,p) basis set. Additionally, the results of the preliminary screening indicate that some of the examined hybrids showed potent antimicrobial activity, compared to standard drugs. The results confirm that the antimicrobial activity is strongly dependent on the nature of the substituents linked pyrazole and isoxazoline rings. Furthermore, molecular docking studies were conducted to highlight the interaction modes between the investigated hybrid compounds and the Escherichia coli and Candida albicans receptors. Notably, the results demonstrate that the investigated compounds have strong protein binding affinities. The stability of the formed complexes by the binding between the hybrid compound 6c, and the target proteins was also confirmed using a 100 ns molecular dynamics simulation. Finally, the prediction of ADMET properties suggests that almost all hybrid compounds possess good pharmacokinetic profiles and no signs of observed toxicity, except for compounds 6e, 6f, and 6g.

Cited By 2International audienceIn this work, a theoretical study on five organic π-conjugated molecules based on thieno[3,2-b][1]benzothiophene using together quantum methods, density functional theory (DFT) and its derivative time dependent-density functional theory (TD-DFT) is reported. Different electron side groups were introduced as a bridge to investigate their effects on the electronic structure; The HOMO, LUMO, chemical hardness (η), chemical potential (μ), electronegativity (χ), electrophilicity power (ω), reorganization energy total (λtotal), open circuit voltage (Voc), the gap energy and NBO analysis of these compounds have been reported and discussed in this paper. Thus, our aim is to explore their electronic and spectroscopic properties on the basis of the DFT quantum chemical calculations, and at the same time, we are interested to make an idea on the parameters influencing the photovoltaic efficiency toward a better understanding of the structure–property relationships. The calculated results of these compounds reveal that C4, C5, with thiophene and thienopyrazine as a bridge group respectively, can be used as a potential donor of electron in organic Bulk Heterojunction solar cells (BHJ), due to its best electronic and optical properties and good photovoltaic parameters. The study of electronic, optical and structural properties of these compounds could help to design more efficient functional photovoltaic organic materials. © 2017 King Saud Universit

International audienceIn this work, theoretical study by using the DFT method on eleven conjugated com- pounds based on thienopyrazine is reported. Different electron side groups were introduced to investigate their effects on the electronic structure; The HOMO, LUMO and Gap energy of these compounds have been calculated and reported in this paper. A systematic theoretical study of such compound has not been reported as we know. Thus, our aim is first, to explore their electronic and spectroscopic properties on the basis of the DFT quantum chemical calculations. Second, we are interested to elucidate the parameters that influence the photovoltaic efficiency toward better under- standing of the structure-property relationships. The study of structural, electronic and optical properties for these compounds could help to design more efficient functional photovoltaic organic materials

In this paper, six symmetrical compounds with a donor–acceptor–donor (D–A–D) structure based on triphenylamine as a core and bridged with various spacer fragments with electron-acceptor character, such as quinoxaline, phenazine, benzo[g]quinoxaline, benzo[b]phenazine, thieno[3,4-b]pyrazine and thieno[3,4-b]quinoxaline, have been studied theoretically using two quantum methods, DFT and TD-DFT, together by considering their use in organic BHJ solar cells as potential donors of electron. Intramolecular charge transfer (ICT) interactions have been found for all of the compounds due to the electron withdrawing properties caused by the two imine nitrogen atoms in the pyrazine and the electron-donating properties of the other two amine nitrogen atoms in the two triphenylamines that compose the bridge. The ICT interactions are strengthened when the benzene or thiophene ring are fused on the pyrazine acceptor unit, which leads to a bathochromic shift of the ICT band. Moreover, our quantum calculations show that thiophene is a more appropriate ring than the benzene ring for enlarging the ICT interactions and expanding the absorption spectrum. We remark also that when a thiophene ring is fused on the quinoxaline unit in the D6 compound, a significant shift towards the near-infrared is realized, and it exhibits a maximum absorption wavelength at 690 nm compared to the other studied compounds with a threshold that is over 800 nm. This is attributed to the enhanced charge density on the acceptor spacer and narrow band gap of this compound, as revealed by our theoretical calculations. Finally, these results show that extending the conjugation of a compound based on pyrazine as an acceptor in a D–A–D structured compound can be realized by incorporating the thiophene unit in the bridge and then strengthening the ICT interactions.