Estimation of the Efficiency of Corrosion Inhibition by Zn-Dithiocarbamate Complexes: a Theoretical Study

Seven Zn-dithiocarbamate complexes were suggested as corrosion inhibitors. Density functional theory (DFT) was used to predict the ability of inhibition. Room temperature conditions were applied to suggest the optimization of complexes, physical properties, and corrosion parameters. In addition, the HOMO, LUMO, dipole moment, energy gap, and other parameters were used to compare the inhibitors efficiency. Gaussian 09 software with LanL2DZ basis set was used. Total electron density (TED) and electrostatic surface potential (ESP) were utilized to show the sites of adsorption according to electron density.

Ascorbic Acid as an Inhibitor for SARS-CoV-2 Virus Reproduction: A Theoretical Approach

In the present study, ascorbic acid’s or Vitamin C’s influence (VC) in inhibition of SARS-CoV-2 virus reproduction was investigated. Gaussian 09 with a basis set of 6-311G (d, p), MGL tools, DSV, and LigPlus software were used. According to the Total Electron Density (TED) and Millikan charges, the active sites for adsorption were determined. Further, the docking study had clearly revealed the role of VC in inhibition of the virus reproduction in accordance with binding energy (Eb) and ligand efficiency (LE). The vitamin’s interaction with the virus’s spikes may limit its replication or provide the immune system sufficient time to recognize the infection, which enhances the possibility of producing appropriate antibodies.

Direct Yellow 8 Azo Removal by Bentonite Clay Solution: Experimental and Theoretical Studies

In the theoretical part, removal of direct yellow 8 (DY8) from water solution was accomplished using Bentonite Clay as an adsorbent. Under batch adsorption, the adsorption was observed as a function of contact time, adsorbent dosage, pH, and temperature. The equilibrium data were fitted with the Langmuir and Freundlich adsorption models, and the linear regression coefficient R2 was used to determine the best fitting isotherm model. thermodynamic parameters of the ongoing adsorption mechanism, such as Gibb's free energy, enthalpy, and entropy, have also been measured. The batch method was also used for the kinetic calculations, and the day's adsorption assumes first-order rate kinetics. The kinetic studies also show that the intraparticle diffusion process was active. Density Functional Theory (DFT) was used to study the dye structure with Gaussian 09 and predict the active site in a molecule using total electron density (TED) and electrostatic surface potential (ESP).

Spectroscopic and computational studies on a Dansyl based luminescent probe : Detection of water contaminant in hygroscopic deuterated solvents

: A Dansyl functionalized fluorescent probe (DFFP) has been intended, synthesized, and well-characterized (NMR, IR, Mass, SEM, SCXRD), capable of sensing trace amounts of water contaminant in hygroscopic deuterated solvents by providing color change under UV irradiation. A distinct bathochromic shift in emission spectra of probe DFFP, as well as the visual color change (Green to Yellow) under UV lamp, are the key evidence of the presence of water. To prove the potentiality of the probe while detecting the remnant water, we did some experimental studies along with exhaustive theoretical evaluation. DFT (Energy optimization and other calculations) helped in better understanding the sensing mechanism and the mode of interactions among probe-water-solvent. Total electron density mapped over Electrostatic Potential Surface and calculation of ESP charges helped in locating more electron-dense regions in the ground state. The involvement of TD-DFT studies helped in finding the possible electronic transitions and corresponding absorption bands. Moreover, the probe is capable of sensing ethanolic water vapour in the gaseous phase. Due to high fluorescence and being nontoxic to cells, probe DFFP could be used as a potential cell imaging dye. It has been employed to human cancer cell line (A549), and fluorescent confocal microscopic images were obtained.

Optimized Atomic Partial Charges and Radii Defined by Radical Voronoi Tessellation of Bulk Phase Simulations

We present a novel method for the computation of well-defined optimized atomic partial charges and radii from the total electron density. Our method is based on a two-step radical Voronoi tessellation of the (possibly periodic) system and subsequent integration of the total electron density within each Voronoi cell. First, the total electron density is partitioned into the contributions of each molecule, and subsequently the electron density within each molecule is assigned to the individual atoms using a second set of atomic radii for the radical Voronoi tessellation. The radii are optimized on-the-fly to minimize the fluctuation (variance) of molecular and atomic charges. Therefore, our method is completely free of empirical parameters. As a by-product, two sets of optimized atomic radii are produced in each run, which take into account many specific properties of the system investigated. The application of an on-the-fly interpolation scheme reduces discretization noise in the Voronoi integration. The approach is particularly well suited for the calculation of partial charges in periodic bulk phase systems. We apply the method to five exemplary liquid phase simulations and show how the optimized charges can help to understand the interactions in the systems. Well-known effects such as reduced ion charges below unity in ionic liquid systems are correctly predicted without any tuning, empiricism, or rescaling. We show that the basis set dependence of our method is very small. Only the total electron density is evaluated, and thus, the approach can be combined with any electronic structure method that provides volumetric total electron densities—it is not limited to Hartree–Fock or density functional theory (DFT). We have implemented the method into our open-source software tool TRAVIS.

Comparison of Bifurcated Halogen with Hydrogen Bonds

Bifurcated halogen bonds are constructed with FBr and FI as Lewis acids, paired with NH3 and NCH bases. The first type considered places two bases together with a single acid, while the reverse case of two acids sharing a single base constitutes the second type. These bifurcated systems are compared with the analogous H-bonds wherein FH serves as the acid. In most cases, a bifurcated system is energetically inferior to a single linear bond. There is a larger energetic cost to forcing the single σ-hole of an acid to interact with a pair of bases, than the other way around where two acids engage with the lone pair of a single base. In comparison to FBr and FI, the H-bonding FH acid is better able to participate in a bifurcated sharing with two bases. This behavior is traced to the properties of the monomers, in particular the specific shape of the molecular electrostatic potential, the anisotropy of the orbitals of the acid and base that interact directly with one another, and the angular extent of the total electron density of the two molecules.

Understanding the Dipole Moment of Liquid Water from a Self-Attractive Hartree Decomposition

<p>The dipole moment of a single water molecule in liquid water has been a critical concept for understanding water’s dielectric properties. In this work, we investigate the dipole moment of liquid water through a self-attractive Hartree (SAH) decomposition of total electron density computed by density functional theory, on water clusters sampled from ab initio molecular dynamics simulation of bulk water. By adjusting one parameter that controls the degree of density localization, we reveal two distinct pictures of water dipoles that are consistent with bulk dielectric properties: a localized picture with smaller and less polarizable monomer dipoles, and a delocalized picture with larger and more polarizable monomer dipoles. We further uncover that the collective dipole-dipole correlation is stronger in the localized picture and is key to connecting individual dipoles with bulk dielectric properties. Based on these findings, we suggest considering both individual and collective dipole behaviors when studying the dipole moment of liquid water, and propose new design strategies for developing water models.</p>

Understanding the Dipole Moment of Liquid Water from a Self-Attractive Hartree Decomposition

<p>The dipole moment of a single water molecule in liquid water has been a critical concept for understanding water’s dielectric properties. In this work, we investigate the dipole moment of liquid water through a self-attractive Hartree (SAH) decomposition of total electron density computed by density functional theory, on water clusters sampled from ab initio molecular dynamics simulation of bulk water. By adjusting one parameter that controls the degree of density localization, we reveal two distinct pictures of water dipoles that are consistent with bulk dielectric properties: a localized picture with smaller and less polarizable monomer dipoles, and a delocalized picture with larger and more polarizable monomer dipoles. We further uncover that the collective dipole-dipole correlation is stronger in the localized picture and is key to connecting individual dipoles with bulk dielectric properties. Based on these findings, we suggest considering both individual and collective dipole behaviors when studying the dipole moment of liquid water, and propose new design strategies for developing water models.</p>

Understanding the Dipole Moment of Liquid Water from a Self-Attractive Hartree Decomposition

<p>The dipole moment of a single water molecule in liquid water has been a critical concept for understanding water’s dielectric properties. In this work, we investigate the dipole moment of liquid water through a self-attractive Hartree (SAH) decomposition of total electron density computed by density functional theory, on water clusters sampled from ab initio molecular dynamics simulation of bulk water. By adjusting one parameter that controls the degree of density localization, we reveal two distinct pictures of water dipoles that are consistent with bulk dielectric properties: a localized picture with smaller and less polarizable monomer dipoles, and a delocalized picture with larger and more polarizable monomer dipoles. We further uncover that the collective dipole-dipole correlation is stronger in the localized picture and is key to connecting individual dipoles with bulk dielectric properties. Based on these findings, we suggest considering both individual and collective dipole behaviors when studying the dipole moment of liquid water, and propose new design strategies for developing water models.</p>