Push–pull effect on the charge transfer, and tuning of emitting color for disubstituted derivatives of mer-Alq3

Insighting the optoelectronic, charge transfer and biological potential of benzo-thiadiazole and its derivatives

The current investigation applies the dual approach containing quantum chemical and molecular docking techniques to explore the potential of benzothiadiazole (BTz) and its derivatives as efficient electronic and bioactive materials. The charge transport, electronic and optical properties of BTz derivatives are explored by quantum chemical techniques. The density functional theory (DFT) and time dependent DFT (TD-DFT) at B3LYP/6-31G** level of theory utilized to optimize BTz and newly designed ligands at the ground and first excited states, respectively. The heteroatoms substitution effects on different properties of 4,7-bis(4-methylthiophene-2yl) benzo[c] [1,2,5]thiadiazole (BTz2T) as initial compound are studied at molecular level. Additionally, we also study the possible inhibition potential of COVID-19 from benzothiadiazole (BTz) containing derivatives by implementing the grid based molecular docking methods. All the newly designed ligands docked with the main protease (M^PRO:PDB ID 6LU7) protein of COVID-19 through molecular docking methods. The studied compounds showed strong binding affinities with the binding site of M^PRO ranging from -6.9 to -7.4 kcal/mol. Furthermore, the pharmacokinetic properties of the ligands are also studied. The analysis of these results indicates that the studied ligands might be promising drug candidates as well as suitable for photovoltaic applications.

Effects of the terminal donor unit in dyes with D-D-π-A architecture on the regeneration mechanism in DSSCs: a computational study

This theoretical study on dye-sensitized solar cells (DSSCs) includes design strategies for dye donor units to improve the efficiency of DSSCs, and further illuminates the organic dye regeneration mechanism. We have designed a series of new organic sensitizers based on a D-D-π-A architecture to exhibit easy electron transfer and to have remarkable light harvesting properties in the visible region by density functional theory (DFT) and time-dependent (TD)-DFT calculations. Furthermore, the interaction of the organic sensitizers with the conventional redox electrolyte using the triiodide/iodide couple (I3-/I-) is investigated. Our calculations indicate that incorporation of strong electron-donating groups remarkably improves the charge transfer characteristics, optoelectronic properties and rapid dye regeneration as compared to less electron donating substituents. In addition, our study demonstrates the possibility of second electron injection from the oxidized dye complex to the semiconductor surface, which further confirms our recently proposed dye regeneration mechanism.

Effect of donor strength of extended alkyl auxiliary groups on optoelectronic and charge transport properties of novel naphtha[2,1-b:6,5-b']difuran derivatives: simple yet effective strategy

The present study spotlights the designing of new derivatives of 2,7-bis (4-octylphenyl) naphtho [2,1-b:6,5-b'] difuran (C8-DPNDF) by substituting the alkyl groups (methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl groups) at para position. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods are employed to optimize the molecular structures in ground and first excited states, respectively. Several electro-optical properties including hole/electron reorganization energies (λh/λe), electron affinities (EAs), ionization potentials (IPs), molecular electrostatic potentials (MEP), and frontier molecular orbitals (FMOs) have been evaluated. Furthermore their transfer integrals and intrinsic mobilities values have also been calculated. From this study, it is found that hole mobility of octyl containing derivative is raised to 4.69 cm(2) V(-1) s(-1). Moreover with attaching octyl group, hole transfer integral values have also been enhanced in newly designed derivatives. The balanced hole and electron reorganization energies, and improved transfer integrals lead to enhanced mobility in derivatives with octyl group, highlighting them as an efficient hole transfer material. Unlike the other electro-optical properties, the intrinsic hole mobility has increased because of transfer integral values of octyl containing derivative C8-DPNDF due to the dense and close crystal packing of C8-DPNDF. However, photostability of furan-based materials has not changed by increasing length of extended alkyl chain. Thus our present investigation highlights the importance of alkyl auxiliary groups that are often neglected/replaced with simple methyl group to save computation costs. Graphical Abstract The hole and electron reorganization energies of naphtho[2,1-b:6,5-b']difuran derivatives.

Influence of push–pull configuration on the electro-optical and charge transport properties of novel naphtho-difuran derivatives: a DFT study

By a push–pull strategy, highly efficient and photostable naphtho-difuran derivatives were designed to get improved intrinsic electron mobility (1.13 cm² V⁻¹ s⁻¹).

Synthesis, characterization and density functional theory investigations of the electronic, photophysical and charge transfer properties of donor-bridge-acceptor triaminopyrazolo[1,5-a]pyrimidine dyes

We have synthesized multifunctional dyes 3-(4-methyl-phenylazo)-6-(4-nitro-phenylazo)-2,5,7-triaminopyrazolo[1,5-a]pyrimidine (4a) and 3-(4-methyl-phenylazo)-6-(4-acetyl-phenylazo)-2,5,7-triaminopyrazolo[1,5-a]pyrimidine (4b), then characterized by IR, (1)H NMR and (13)C NMR techniques. The ground state geometries have been computed by using density functional theory at B3LYP/6-31G(*) level of theory. The absorption spectra have been calculated by using time dependent density functional theory with and without solvent. The highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) are delocalized and localized on throughout the backbone, respectively. Solvent also play important role towards elevating the dipole moment. Significant red shift in absorption wavelengths have been observed in methanol compared to without solvent. We discussed the electron injection, electronic coupling constant and light harvesting efficiency.

Quantum chemical study of the donor-bridge-acceptor triphenylamine based sensitizers

Quantum chemical calculations were carried to investigate the electron coupling, electron injection, electronic and photophysical properties of 2-cyano-5-(4-(phenyl(4-vinylphenyl)amino)phenyl) penta-2,4-dienoic acid (TC4) and its derivatives. Geometries have been optimized by using density functional theory at B3LYP/6-31G(**) level of theory. The highest occupied molecular orbitals (HOMOs) are delocalized on triphenylamine (TPA) units while lowest unoccupied molecular orbitals LUMOs are localized on anchoring groups. The mono-methyl is more significant to lowering the energy gap than di and tri-methyl substituted ones. The HOMOs of the dyes are below the redox couple and LUMOs are above the conduction band of TiO2. We have explained the recombination barrier on the basis of distortion and coplanarity. The excitation energies have been computed by time dependent density functional theory at PCM-CAM-B3LYP/6-31G(**) level of theory. Enhanced bridge is encouraging to promote the electron injection, electronic coupling constant and light harvesting efficiency. Generally, electron injection, electronic coupling constant and light harvesting efficiency of new designed sensitizers are higher than TC4. This revealed that new materials would be efficient photosensitizers.

Donor-enhanced bridge effect on the electronic properties of triphenylamine based dyes: density functional theory investigations

The geometries have been optimized by using density functional theory. The highest occupied molecular orbitals are delocalized on triphenylamine moiety while lowest unoccupied molecular orbital are localized on anchoring group. Intramolecular charge transfer has been observed from highest occupied molecular orbitals to lowest unoccupied molecular orbital. By replacing the vinyl hydrogens with methoxy as well as one benzene ring as bridge leads to a raised energy gap while extending the bridge decreases the energy gap compared to parent molecule. The HOMO energies bump up by extending the bridge. The LUMO energies of all the investigated dyes are above the conduction band of TiO(2) and HOMOs are below the redox couple except 3c. The distortion between anchoring group and triphenylamine can hamper the recombination reaction.

Designing of Disubstituted Derivatives of mer-Alq3: Quantum Theoretical Study

Different disubstituted derivatives of tris(8-hydroxyquinolinato)aluminium (mer-Alq3) have been designed. An electron donating group (–CH3) has been substituted at position 4; along with electron withdrawing groups (–Cl, –CN, and –F) at position 5 (i.e. tris(4-X-5-Y-8-hydroxyquinolinato)aluminium), as well as the molecules arising from reversion of these substitutions. The designed systems have been optimized at the B3LYP/6–31G* and TD-B3LYP/6–31G* level of theories, in the ground and excited states, respectively. The absorption and emission spectra have been calculated at the TD-B3LYP/6–31G* level. A significant blue shift has been observed for tris(4-methyl-5-cyano-8-hydroxyquinolinato)aluminium (2), and red shifts for each of tris(4-methyl-5-fluoro-8-hydroxyquinolinato)aluminium (3), tris(4-chloro-5-methyl-8-hydroxyquinolinato)aluminium (4), and tris(4-cyano-5-methyl-8-hydroxyquinolinato)aluminium (5). The reorganization energy in solvent best elucidates the charge transport behaviour (p- or n-type), rather than the equivalent gas phase for mer-Alq3 and its derivatives. The reorganization energies indicate that these new derivatives have better or comparable mobility when compared to the parent molecule. The electrostatic surface potential study suggested that photostability would be enhanced. On the basis of energy decomposition analysis, we have explained the distribution pattern of frontier molecular orbitals.