In the current study, the DFT and TD-DFT methods are used to investigate seven donor–π-acceptor (D–π–A) dyes, named DY01 to DY07, which are planned for utilization in DSSCs. The HOMO-LUMO gaps are decreased due to the solvent effect by 0.05-0.16 eV and are smallest (1.85 eV) for DY01. Frontier molecular orbitals show that charge separation is efficient between triphenylamine donor and cyanoacrylic acid acceptor. The bathochromic shift due to the solvent effects is estimated by the TD-DFT calculations, and DY01 exhibits the maximum red shift (638 nm) as well as DY05 has the highest oscillator strength (f = 1.664). Photovoltaic parameters reveal that DY01 is the most efficient (0.958), and DY02 could receive the relatively better electrons injection strength accompanied with high Voc value. Adsorption on (TiO₂)₈ cluster has an additional decrease the energy gaps and DY01 and DY07 show strong red shifts. Upon adsorption, the orbital distribution shows strong electronic coupling conducive to photo-induced electron transfer to the semiconductor. It can be concluded that DY01 is the most efficient sensitizer showing highest quantum efficiency due to its narrow band gap, effective intramolecular charge transfer (ICT), high light-harvesting efficiency (LHE) and favorable interfacial properties.

Dye-sensitized solar cells (DSSCs) represent a highly promising new generation of photovoltaic devices that offer an attractive alternative to traditional silicon-based solar cells due to their low production costs, simple manufacturing, and adaptable optoelectronic properties. Titanium dioxide (TiO₂) is extensively utilized as a semiconductor in DSSCs due to the favorable position of its conduction band, high chemical stability, abundance, and non-toxicity. As part of this work, an in-depth computational study was conducted on five organic dyes (D1 to D5) to investigate their potential as effective sensitizers for DSSC applications. Density functional theory (DFT) and time-dependent DFT (TD-DFT) were employed to investigate their structural, electronic, and optical properties, as well as their key photovoltaic parameters. The HOMO energy levels calculated (−5.99 to −6.36 eV) were low enough to allow efficient dye regeneration by the electrolyte, while the LUMO levels (−3.05 to −3.71 eV) were located above the conduction band edge of TiO₂ (−4.0 eV), Calculated band gaps (2.35–2.94 eV) supported strong absorption in the visible range, and open-circuit voltages (0.26–0.94 eV) suggested good photovoltaic potential. Furthermore, all dyes presented positive free electron injection energy (ΔGinject), evidencing thermodynamically favorable charge transfer processes. Benchmarking revealed that structural modifications between dyes were found to be significantly.

The study of cycloaddition reactions between cyclopenta-1,3-diene and benzyl-acrylate, as well as benzyl-2-fluoroacrylate with and without the catalyst (TiCl4), was conducted using MEDT. The results of the energy profiles suggest that these reactions are stereoselective, meaning that they favor the formation of certain stereoisomers over others. Furthermore, the addition of TiCl4 as a catalyst appears to enhance the selectivity of these reactions, which is in line with experimental observations. Additionally, a docking study was carried out to predict the effect of stereochemistry and the presence of specific atoms, such as fluorine, on their ability to bind to viral proteins responsible for SARS-Covid-19 and HIV. Moreover, the notable affinity of Ligand 4 for HIV renders it a pivotal contender for extended research, possibly paving the way for enhanced antiretroviral drugs. Similarly, the encouraging affinity demonstrated by Ligand 1 towards the Covid-19 protein highlights its promise for Covid-19 drug development.

This study employs Molecular Electron Density Theory (MEDT) to explore the [3+2] cycloaddition mechanisms involving 1-methyl-4-(prop-1-en-2-yl)cyclohex-1-ene (2-R) and nitrile oxide (3-R). Density Functional Theory (DFT) calculations using the B3LYP/6-311(d,p) method were performed to determine reactivity indices, activation energies, and reaction energies. The conceptual DFT analysis indicates that 1-methyl-4-(prop-1-en-2-yl)cyclohex-1-ene 2-R acts as a nucleophile, while nitrile oxide 3-R functions as an electrophile. The reaction exhibits notable chemoselectivity and regioselectivity, supported by activation energies that align with experimental data. BET analysis suggests a one-step mechanism with asynchronous bond formation. Additionally, molecular docking studies of the reaction products against HIV-1 and COVID-19 reveal that the presence of oxygen and nitrogen atoms enhances the interaction energy with proteins, indicating potential therapeutic benefits.

In this charge we designated a Hilbert-Johnson process by coupling of heterocyclic N-silylated with benzyl chloride at 100°C using the calcined red algae (CRA) doped with ammonium sulfate (AS), AS@CRA as a heterogeneous catalyst. The resulting examination systems, which included atomic absorption, BET methodology and X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and Fourier transform infrared spectroscopy (FT-IR), were employed to describe these catalysts. The effect of catalyst and alkylated agent were extensively studied. This catalyst can also be recycled several times in this condensation, and lastly, we suggested a probable answer mechanism for this process. Moreover, our molecular docking investigation revealed the anti-tuberculosis potential of the synthesized compounds. Notably, the drug isoniazid exhibited higher binding energies compared to the products 2a, 2b, and 2c. Additionally, the ADME study suggests that highly efficacious synthetic compounds may possess anti-tuberculosis properties.

Molecular electron density theory has been performed with the B3LYP/6-31(d,p) method to study the [3+2] cycloaddition processes between azidobenzene and propionaldehyde, the reactivity indices, activation and reaction energies are computed. The reaction and activation energies indicate that this [3+2] cycloaddition reaction is regiospecific, in good agreement with the experimental results. ELF examination revealed that the mechanism of these cycloaddition reactions takes place in two steps. In addition, a docking approach was performed on the products investigated, and the interaction with the protein protease COVID-19 (PDB ID: 6LU7), the results confirm that the presence of triazole and isoxazole rings increases the affinity of these products.

In this work, ribonucleoside products have been prepared by employing stannic tetrachloride (SnCl4) and natural phosphate as catalysts. The obtained result suggests that this catalyst facilitates the reactions of ribonucleoside-like products in a stereo-controlled manner, exhibiting β-selectivity when reacting with trimethylsilyl uracil, the ribonucleosides derivatives were obtained in suitable yields. In addition, we have performed the molecular docking analysis, demonstrated that the synthesized compounds have potential for antiviral activity against the omicron variant of coronavirus, and the D3, D4, E and F products have a higher binding energy than the molnupiravir drug, indicating that these products may be a probable drugs for the omicron variant.

The inhibiting effect of chloroquine compounds (ChCs) on the SARS-CoV-2 virus represents a highly debated form of study owing to the emerging proposals of mechanistic implications for exploring the mode of action of ChCs on the virus. Keeping in view the emerging significance of chloroquine derivatives, the present study was performed to screen one hundred and ninety known chloroquine derivatives for their interaction with several SARS-CoV-2 target proteins by molecular docking and molecular dynamics simulations to obtain an in-depth understanding of the potential hits of these compounds against SARS-CoV-2. A total of 190 molecules from the chloroquine family were screened for the identification of potential new inhibitors of the three therapeutic target proteins of SARS-CoV-2, namely Mpro (master protease), PLpro (papain-like protease) and SGp-RBD (spike glycoprotein receptor binding domain). The ChCs bound to SARS-COV-2 Mpro, PLpro, and SGp-RBD were generated by molecular docking and molecular dynamics simulations. Herein, a comparative analysis of chloroquine family products and a well-known drug against SARS-CoV-2, called Remdesivir, has also been presented. This investigation is intended to study the mechanism of interaction between ChCs and the SARS-CoV-2 virus and explore the unprecedented areas associated with the inhibitory activity of ChCs against this virus.

Application of the Molecular Electron Density Theory (MEDT) for the exploration of the [3+2] cycloaddition processes between methyl propynoate 1 and difluoromethyldiazomethane T-1, have been implemented using the DFT/B3LYP/6-311(d,p) level of theory. According to an examination of conceptual DFT indices, difluoromethyldiazomethane (T-1) participates in this reaction as a nucleophile, while methyl propynoate (1) should be considered as an electrophile. This cyclization is regiospecific, as evidenced by the activation and reaction energies, this agrees with the experiment's findings. It was discovered throughout ELF analysis that analyzed [3+2] cycloaddition is realised by a two-step mechanism. In addition, study of interactions of the products studied in this paper with the protein protease Covid-19 (PDB ID: 7R98) were carried out, by means of molecular docking study). The results indicate that the occurrence of the transfer of the proton to the nitrogen atom, increases the affinity of these products to the protein (CA32-F1 and CA32-F2).