Density functional investigation of photo induced Intramolecular Proton Transfer (IPT) in Indole-7-carboxaldehyde and its experimental verification

Study of clopidogrel and clonidine interactions for cardiovascular formulations: progress from DFT modeling

The drugs clopidogrel and clonidine are frequently used to treat cardiovascular diseases, which are the leading cause of mortality worldwide. Since these medications are frequently taken in combination, it is crucial to examine their molecular interactions. Therefore, herein, the bandgap energy, chemical potential, chemical hardness and softness parameters were calculated using a density functional theory (DFT)-based method. In addition, infrared (IR) spectrum, natural bond orbital (NBO), molecular electrostatic potential (MEP), electron localization function (ELF) and total density of states (TDOS) plots complemented the analysis. Clonidine exhibited greater sensitivity to electrophilic attack, while the electronic affinity of clopidogrel was slightly higher. According to the MEP map, negative charge density was located on the oxygen atoms of clopidogrel, and the positive charge was located on the nitrogen atoms of clonidine. Notably, both the drugs exhibited similar reactivity in water. Clopidogrel was less reactive than clonidine, and the interaction between the molecules occurred via physisorption, which was in agreement with the TDOS plot. NBO analysis revealed a low charge variation, in accordance with the physical adsorption-like bonding between the drugs. The lowest energy for the clopidogrel-clonidine interaction was attained via the formation of four H bonds, as indicated by a significant intensive peak at 3360 cm-1 in the IR spectrum. Hydrogen bonds played a crucial role in the controlled drug delivery application as it allowed moderate and reversible drug adsorption, facilitating drug release in the biological environment. IR spectra also supported the absence of degradation or chemical reaction between the drugs, confirming the preservation of the individual active pharmaceutical ingredient.

Tuning optoelectronic properties of indandione-based D-A materials by malononitrile group acceptors: A DFT and TD-DFT approach

CONTEXT

Indandione-based materials are promising candidates for organic electronics, offering high electron mobility and tunable optoelectronic properties. In this study, we explore the optoelectronic and photovoltaic properties of indandione-based donor-acceptor (D-A) materials, specifically (R1) and (R2), by introducing malononitrile group acceptors into their molecular structure. These strong electron-withdrawing acceptors are designed to enhance charge transfer and overall material performance. The designed molecules (DM1-DM4) exhibit a low optical band gap of approximately 1.77 eV, significantly lower than the reference materials (R1 and R2) at around 2.24 eV in a solvent environment. Among the designed molecules, DM4 stands out with superior photovoltaic parameters, including a narrow optical band gap (1.77 eV), higher electron affinity (3.49 eV), an extended excited state lifetime (10.0 ns) owing to its low electron and hole reorganization energies (λe ~ 0.13 eV and λh ~ 0.24 eV), and improved short-circuit current density (Jsc) of ~ 15.73 mA/cm2. Notably, DM4 achieves a power conversion efficiency (PCE) of ~ 18.5%, making it an excellent candidate for device applications.

METHOD

A comprehensive computational investigation was carried out on indandione-based D-A materials with malononitrile group acceptors (DM1-DM4) using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods, as implemented in Gaussian 16 software. We examined the electronic and optical properties of the proposed molecules through frontier molecular orbital (FMO) analysis, UV-Vis absorption spectra, density of states (DOS), exciton binding energy (Eb), and transition density matrix (TDM) analysis, utilizing GaussView 6.0 and Multiwfn 3.8 software. The photovoltaic parameters and power conversion efficiency (PCE) were evaluated using the Scharber and Alharbi models.

Quantum Chemical Calculation for Intermolecular Interactions of Alginate Dimer-Water Molecules

The abundance of applications of alginates in aqueous surroundings created by their interactions with water is a fascinating area of research. In this paper, computational analysis was used to evaluate the conformation, hydrogen bond network, and stabilities for putative intermolecular interactions between alginate dimers and water molecules. Two structural forms of alginate (alginic acid, alg, and sodium alginate, SA) were evaluated for their interactions with water molecules. The density functional theory (DFT-D3) method at the B3LYP functional and the basis set 6-31++G** was chosen for calculating the data. Hydrogen bonds were formed in the Alg-(H₂O)_n complexes, while the SA-(H₂O)_n complexes showed an increase in Van der Walls interactions and hydrogen bonds. Moreover, in the SA-(H₂O)_n complexes, metal-nonmetal bonds existed between the sodium atom in SA and the oxygen atom in water (Na…O). All computational data in this study demonstrated that alginate dimers and water molecules had moderate to high levels of interaction, giving more stability to their complex structure.