A comparative study of deep eutectic solvents based on fatty acids and the effect of water on their intermolecular interactions

In this work, intermolecular interactions among the species of fatty acids-based DESs with different hydrogen bond acceptors (HBA) in the adjacent water have been investigated using molecular dynamics (MD) simulation. The results of this work provide deep insights into understanding the water stability of the DESs based on thymol and the eutectic mixtures of choline chloride and fatty acids at a temperature of 353.15 K and atmospheric pressure. Stability, hydrogen bond occupancy analysis, and the distribution of the HBA and HBD around each other were attributed to the alkyl chain length of FAs and the type of HBA. Assessed structural properties include the combined distribution functions (CDFs), the radial distribution functions (RDFs), the angular distribution functions (ADFs), and the Hydrogen bonding network between species and Spatial distribution functions (SDF). The reported results show the remarkable role of the strength of the hydrogen bond between THY molecules and fatty acids on the stability of DES in water. The transport properties of molecules in water-eutectic mixtures were analyzed by using the mean square displacement (MSD) of the centers of mass of the species, self-diffusion coefficients, vector reorientation dynamics (VRD) of bonds and the velocity autocorrelation function (VACF) for the center of the mass of species.

Effect of water addition on caprylic acid: Quaternary ammonium salts (QAS) deep eutectic solvents: Characterization of their structural and dynamical properties

Physicochemical properties of the binary mixtures based on Caprylic acid: Quaternary ammonium salts (QAS) (7:3 mol ratio) are investigated using MD simulations. Considering the hydrophobic character of eutectic solvents based on long-chain fatty acids, the stability of the binary mixtures was investigated in the adjacent water. In order to investigate the effect of water on intermolecular interactions in binary mixtures, the structural properties of the binary mixtures in the pure state and adjacent to water were investigated at 310 K. Assessed structural properties include the combined distribution functions (CDFs), the radial distribution functions (RDFs), the angular distribution functions (ADFs), and the Hydrogen bonding network between HBA and HBD and Spatial distribution functions (SDF). We aimed to represent the structural stability of eutectic solvents based on Caprylic acid and Quaternary ammonium salts (QAS) as a function of the alkyl chain length of cations, the evidence was found for the interaction between the chloride anion leads to the transition of HBA to the water-rich phase. The alkyl chain length of cations of Quaternary ammonium salts shows the stability of eutectic solvents in the adjacent water.

Assessment of the properties of natural-based chiral deep eutectic solvents for chiral drug separation: insights from molecular dynamics simulation

The structural and physicochemical properties of chiral deep eutectic solvents (DESs) consisting of racemic mixtures of menthol and acetic acid (DES1), racemic mixtures of menthol and lauric acid (DES2), and racemic mixtures of menthol and pyruvic acid (DES3) for enantioselective extraction processes are investigated. Structural results, such as the radial distribution function (RDF) and the combined distribution function (CDF), indicate that the hydroxyl hydrogen of menthol has a dominant interaction with the carbonyl oxygen of the acids in the considered DESs. The number of hydrogen bonds and non-bonded interaction energies formed between S-menthol and HBDs are larger than those with R-menthol, resulting in the self-diffusion coefficient of S-menthol being larger than that of R-menthol. Therefore, it can be said that the proposed DESs are good candidates for the separation of drugs with S chirality. The effects of acid type on the density and isothermal compressibility of DESs show the behaviour of DES2 > DES3 > DES1 and DES1 > DES3 > DES2, respectively. Our results provide a better perspective on new chiral DESs at the molecular level for enantioselective processes.

Investigation the effect of water addition on intermolecular interactions of fatty acids-based deep eutectic solvents by molecular dynamics simulations

In this work, we focused on the interaction between hydrogen bond acceptor (HBA) and hydrogen bond doner (HBD) in the binary mixtures. The results showed that Cl^- anion plays a key role in the formation of DESs. Also, the structural stability of deep eutectic solvents based on fatty acids (FAs) and choline chloride (Ch⁺Cl^-) at different ratios was investigated in water using molecular dynamics simulations. We observed that the interaction between the chloride anion and the hydroxyl group of the cation leads to the transition of HBA to the water-rich phase. These atomic sites have important rule in the stability of the eutectic mixtures based on FAs and Cl^- anion. However, it seems that the binary mixtures with the mole percent at 30% of [Ch⁺Cl^-] and 70% of FAs have more stability than other ratios.

Quantum DFT methods to explore the interaction of 1-Adamantylamine with pristine, and P, As, Al, and Ga doped BN nanotubes

Nanostructures, nowadays, found growing applications in different scientific and industrial areas. Nano-coins, nanosheets, and nanotubes are used in medical applications as sensors or drug delivery substances. The aim of this study is to explore the adsorption of 1-Adamantylamine drug on the pristine armchair boron nitride nanotubes (BNNTs) with BNNT(5,5), BNNT(6,6), and BNNT(7,7) chirality along with the P, As, Al and Ga-doped BNNTs, using the quantum mechanical density functional methods. Considering the fact that dispersion effects are important in the case of weak Van der Waals interactions, computations have been done using B3LYP hybrid functional with the implementation of the D3(BJ) empirical dispersion correction methods. Quantum theory of atoms in molecules, natural bonding orbitals, and Kohn-Sham orbitals were used to investigate the nature and type of the adsorption process. The results showed that, while the adsorption of 1-Adamantylamine on the outer surface of pristine BNNT is physical in nature, doping can improve the ability of detracted BN to adsorb the drug through chemical bonds. Also, it was found that, by increasing the radius of the BNNT the adsorption energy was decreased. In conclusion, results of the present work suggest that, Ga doped nanotube, due the chemisorption, is not an ideal nanotube in drug delivery of 1-Adamantylamine drug, whereas, the other studied cases physiosorbed the drug, and may not have serious problem in release of the 1-Adamantylamine drug.

The adsorption of NO2, SO2, and O3 molecules on the Al-doped stanene nanotube: a DFT study

Adsorption of pollutant gas molecules (NO₂, SO₂, and O₃) on the surface of the Al-doped stanene nanotube was investigated within the first principle calculations of density functional theory (DFT). Adsorption mechanisms were studied by analyzing optimized structures, band structures, projected density of states (PDOS), charge density difference (CDD), molecular orbitals, and band theory. Investigation of charge transfer by Mulliken population showed that NO₂ accumulated while SO₂ and O₃ depleted charge density on the Al-doped nanotube. The differences in band structures before and after adsorption implied that the electronic characteristics of Al-doped nanotube changed dramatically in case of NO₂ adsorption, which converted Al-doped nanotube to a semiconductor material. High adsorption energy and the significant overlap between PDOS spectra indicated that the adsorption process was chemisorption for NO₂, SO₂, and O₃ on the doped nanotube with the obtained order of O₃ > SO₂ > NO₂. The results showed that the adsorption of NO₂, SO₂, and O₃ occurred on the Al-doped stanene nanotube, and that all the three gas molecules could be detected by Al-doped stanene nanotube with various detection strengths.

Copper (II) complexes with N, S donor pyrazole-based ligands as anticancer agents

A group of bidentate nitrogen and sulfur donor pyrazole derivative ligands abbreviated as Na[RNCS(Pz)], Na[RNCS(Pz^Me2)], Na[RNCS(Pz^Me3)], Na[RNCS(Pz^PhMe)], Na[RNCS(Pz^Ph2)], where (R = Et, Ph), and their Cu (II) complexes were synthesized and characterized by spectroscopic and physicochemical methods. The crystal structure of [Cu(PhNCSPz^Me3)₂] was determined by X-ray crystallography analysis and the results described a distorted square planar coordination geometry for this complex. Also, the cyclic voltammetry investigations indicated that the synthesized copper complex is an electrochemically active species. Moreover, the cytotoxic activity of all of the twenty synthesized compounds was evaluated using MTT assay against the MCF-7 (human breast carcinoma) cell lines, in vitro. Cu (II) complexes indicate significant cytotoxicity against the MCF-7 cell lines as compared with the free ligands. The docking studies showed that the copper complexes have better interactions with EGFR and CDK2 proteins, compared to the free ligands, and most of the studied compounds have a higher value of binding energy relative to the studied controls. The results of QSAR analysis suggest that dipole moment is in direct correlation with the obtained IC₅₀ values, and it strongly impact the anticancer effects generated by the compounds. Our findings suggest that the developed copper complexes can be good candidates for further evaluations as chemotherapeutic agents in the treatment of cancer.

Electrochemical reduction of NO catalyzed by boron-doped C60 fullerene: a first-principles study

The electrochemical reduction of nitrogen monoxide (NO) is one of the most promising approaches for converting this harmful gas into useful chemicals. Using density functional theory calculations, the work examines the potential of a single B atom doped C₆₀ fullerene (C₅₉B) for catalytic reduction of NO molecules. The results demonstrate that the NO may be strongly activated over the B atom of C₅₉B, and that the subsequent reduction process can result in the formation of NH₃ and N₂O molecules at low and high coverages, respectively. Based on the Gibbs free energy diagram, it is inferred that the C₅₉B has excellent catalytic activity for NO reduction at ambient conditions with no potential-limiting. At normal temperature, the efficient interaction between the *NOH and NO species might lead to the spontaneous formation of the N₂O molecule. Thus, the findings of this study provide new insights into NO electrochemical reduction on heteroatom doped fullerenes, as well as a unique strategy for fabricating low-cost NO reduction electrocatalysts with high efficiency.

Using DFT calculations, the potential of B-doped C₆₀ fullerene is evaluated for electrochemical reduction of nitrogen monoxide. The B-doped C₆₀ exhibits exceptional catalytic activity and high selectivity for reduction of nitrogen monoxide.

Molecular dynamics simulation study of gold nanosheet as drug delivery vehicles for anti-HIV-1 aptamers

The adsorption process of three aptamers with gold nanosheet (GNS) as a drug carrier has been investigated with the help of molecular dynamics simulations. The sequencing of the considered aptamers are as (CUUCAUUGUAACUUCUCAUAAUUUCCCGAGGCUUUUACUUUCGGGGUCCU) and (CCGGGUCGUCCCCUACGGGGACUAAAGACUGUGUCCAACCGCCCUCGCCU) for AP1 and AP2, respectively. AP3 is a muted version of AP1 in which nucleotide positions 4, 6, 18, 28 and 39 have C4A, U6G, A18G, G28A, and U39C mutations. At positions 24, and 40, a deletion mutation is seen to eliminate U24 and U40 bases. These aptamers are inhibitors for HIV-1 protease and can be candidates as potential pharmaceutics for treatment of AIDS in the future. The interactions between considered aptamers and GNS have been analyzed in detail with help of structural and energetic properties. These analyses showed that all three aptamers could well adsorb on GNS. Overall, the final results show that the adsorption of AP2 on the GNS is more favorable than other considered ones and consequently GNS can be considered as a device in order to immobilize these aptamers.

Influence of curcumin and rosmarinic acid on disrupting the general properties of Alpha-Synuclein oligomer: Molecular dynamics simulation

Alpha-Synuclein (αS) is a protein involved in Parkinson's disease (PD) and is probably the main cause of the pathology of the disease. During pathogenesis, αS monomers aggregate, leading to the formation of a variety of oligomeric species. Recent research studies suggest that the oligomeric toxic species may be one of the main processes for pathology and disease. Here, we studied influence of two natural polyphenolic compounds, Curcumin (CUR) and Rosmarinic acid (RA), on disrupting the general properties of αS oligomer by molecular dynamics (MD) simulation method. The hydrophobic central domain of αS (NAC), is the most essential district responsible for protein self-aggregation; so, in this study, our systems have been developed to form a quintuplet NAC region of αS called 5mer; they have 10 and 20 CUR and RA molecules and a 5mer with no ligand. The several important and efficient analyzes were performed to investigate the effect of ligands on the structural properties of αS oligomers. The results indicated that both ligands can be successful in disrupting the original structure of αS oligomers; therefore, they can be considered suitable candidates for designing Parkinson's drugs.

Molecular dynamics simulations of choline chloride and phenyl propionic acid deep eutectic solvents: Investigation of structural and dynamics properties

The prediction of deep eutectic composition is hard and so far, has been distinguished by trial and error. Therefore, in this work, molecular dynamics simulations were performed for specifying the composition of the eutectic point of phenyl propionic acid (Phpr) and choline chloride (ChCl) mixtures. The distinctive properties of the Phpr and ChCl eutectic mixture at the composition of the eutectic point were investigated and were compared to other eutectic mixtures with the different mole fractions of Phpr and ChCl. Structural properties such as radial distribution function (RDF), coordination number, hydrogen-bond number, interaction energies, and dipole moment of species, as well as dynamical properties such as mean square displacement (MSD), viscosity, and self-diffusion coefficient were analyzed. The obtained results of structural properties indicated that each chloride anion is surrounded by two Phpr molecules for deep eutectic point states that is in good agreement with available experimental reports. Moreover, the viscosity of studied mixtures evaluated by the Green-Kubo method was found to be consistent with the reported experimental data. Besides, the stress-autocorrelation function (SACF) and convergency of viscosity with time were calculated. Finally, the eutectic point could be detected by the changes in the trends of total van der Waals interaction energies and the viscosity.

Insights into the interactions and dynamics of a DES formed by phenyl propionic acid and choline chloride

Deep eutectic solvents (DESs) have received much attention in modern green chemistry as inexpensive and easy to handle analogous ionic liquids. This work employed molecular dynamics techniques to investigate the structure and dynamics of a DES system composed of choline chloride and phenyl propionic acid as a hydrogen bond donor and acceptor, respectively. Dynamical parameters such as mean square displacement, liquid phase self-diffusion coefficient and viscosity are calculated at the pressure of 0.1 MPa and temperatures 293, 321 and 400 K. The system size effect on the self-diffusion coefficient of DES species was also examined. Structural parameters such as liquid phase densities, hydrogen bonds, molecular dipole moment of species, and radial and spatial distribution functions (RDF and SDF) were investigated. The viscosity of the studied system was compared with the experimental values recently reported in the literature. A good agreement was observed between simulated and experimental values. The electrostatic and van der Waals nonbonding interaction energies between species were also evaluated and interpreted in terms of temperature. These investigations could play a vital role in the future development of these designer solvents.

A mechanistic first-principles study on N2 reduction reaction catalyzed by Ni4 supported defective graphene

The electrochemical reduction of N₂ is an important industrial process, which offers an alternative route to the Haber-Bosch procedure for NH₃ production. Here, by the method of first-principles calculations, we introduce Ni₄ supported defective graphene (Ni₄-Gr) as an efficient substrate to convert N₂ into NH₃. The enzymatic, alternating and distal mechanisms are investigated for N₂ reduction to explore catalytic activity of Ni₄-Gr surface. By analyzing the free energy diagrams, it is obtained that Ni₄-Gr exhibits high catalytic performance for N₂ reduction via the enzymatic pathway with an overpotential value of 0.50 V at normal temperature.

Theoretical insights into oxygen reduction reaction catalyzed by phosphorus-doped divacancy C3N nanosheet

The catalytic reduction of O₂ molecule into H₂O is investigated over a P-doped divacancy C₃N nanosheet (P-Dv-C₃N) by using density functional theory calculations. A negative formation energy is calculated for P-Dv-C₃N, suggesting that the introduction of a P atom into divacancy defective C₃N would be thermodynamically favorable. The oxygen reduction reaction (ORR) over P-Dv-C₃N would proceed via a 4e^- pathway (O₂ + 4H⁺ + 4e^-→ 2H₂O) at room temperature. The rate-determining step of the ORR on P-Dv-C₃N is O + H⁺ + e^- → OH which requires an activation energy of 1.21 eV. These results provide helpful insights into design novel metal-free catalysts to improve the kinetics of ORR in fuel cells.

Theoretical investigation of the adsorption behaviors of CO and CO2 molecules on the nitrogen-doped TiO2 anatase nanoparticles: Insights from DFT computations

Over the past years, an interest has arisen in resolving the problems of the increased carbon monoxide and carbon dioxide emissions, leading to the serious air pollution and many detrimental effects. A convenient solution would be a process that could utilize metal oxide nanoparticles such as TiO2 to control the concentration of atmospheric pollutants. The chemisorption of CO and CO2 molecules over the semiconductor titanium dioxide (TiO[Formula: see text] is such a process. In this way, density functional theory (DFT) calculations were performed to investigate CO and CO2 adsorptions on undoped and N-doped TiO2 anatase nanoparticles. The supercell approach is conducted to construct the considered nanoparticles and the adsorption of COx molecule was simulated by use of these chosen nanoparticles. By including van der Waals (vdW) interactions between COx molecule and TiO2 nanoparticle, we found that both CO and CO2 molecules can bind strongly to the N-doped nanoparticles. The adsorption on the five-fold coordinated titanium site of TiO2 nanoparticles including the bond lengths, bond angles, adsorption energies, density of states (DOSs), Mulliken population analysis and molecular orbitals has been broadly studied in this work. Based on the obtained results, it can be concluded that the adsorption on the N-doped nanoparticle is more energetically favorable than the adsorption on the pristine one, representing the higher tendency of N-doped nanoparticles for COx detention, compared to the undoped ones. Therefore, the results indicate that the N-doped TiO2 would be an ideal COx gas sensor in the environment.

An innovative gas sensor system designed from a sensitive nanostructured ZnO for the selective detection of SOx molecules: a density functional theory study

The adsorption behaviors of SO_x molecules on pristine and N-doped ZnO nanoparticles were investigated using density functional theory calculations (DFT).

The Interaction of Acrolein with Pristine and N-doped TiO2 Anatase Nanoparticles: A DFT Study

Density functional theory calculations were carried out in order to study the effects of the adsorption of acrolein molecule on the structural and electronic properties of TiO2 anatase nanoparticles. The ability of pristine and N-doped TiO2 anatase nanoparticles to recognize toxic acrolein (C3H4O) molecule was surveyed in detail. It was concluded that acrolein molecule chemisorbs on the N-doped anatase nanoparticles with large adsorption energy and small distance with respect to the nanoparticle. The results indicate that the adsorption of acrolein on the N-doped TiO2 is energetically more favorable than the adsorption on the pristine one, suggesting that the N doping can energetically facilitate the adsorption of acrolein on the N-doped nanoparticle. It means that the N-doped TiO2 nanoparticle can react with acrolein molecule more efficiently. The interaction between acrolein molecule and N-doped TiO2 can induce substantial variations in the HOMO/LUMO molecular orbitals of the nanoparticle, changing its electrical conductivity which is helpful for developing novel sensor devices for the removal of harmful acrolein molecule. The large overlaps in the projected density of states spectra reveal the formation of chemical bond between two interacting atoms. Charge analysis based on Mulliken charges indicates that charge is transferred from the acrolein molecule to the TiO2 nanoparticle.

The adsorption of SO2 on TiO2 anatase nanoparticles: a density functional theory study

First-principles calculations have been carried out to investigate the adsorption properties of SO2 molecules on nitrogen-doped TiO2 anatase nanoparticles using the density functional theory method to fully exploit the gas-sensing capabilities of TiO2 particles. For this purpose, we have mainly studied the adsorption of the SO2 molecule on the dangling oxygen atom and doped nitrogen atom sites of the TiO2 nanoparticles because these sites are more active than other sites in the adsorption processes. The complex systems consisting of the SO2 molecule positioned toward the undoped and nitrogen-doped nanoparticles have been relaxed geometrically. The results presented include structural parameters such as bond lengths and bond angles and energetics of the systems such as adsorption energies. The electronic structure and its variations resulting from the adsorption process, including the density of states, molecular orbitals, and the charge transfer, are discussed. We found that the adsorption of the SO2 molecule on the nitrogen-doped TiO2 nanoparticles is energetically more favorable than the adsorption on the undoped ones. These results thus provide a theoretical basis for the potential applications of TiO2 nanoparticles in the removal and sensing of SO2 and give an explanation for helping in the optimization of improved gas removers and sensor devices.

Improving the adsorption of sulfur trioxide on TiO2 anatase nanoparticles by N-doping: A DFT study

The adsorptions of sulfur trioxide molecule on undoped and N-doped TiO 2 anatase nanoparticles were investigated by density functional theory (DFT) calculations. N-doped nanoparticles were constructed by substitution of oxygen atoms of TiO2 by nitrogen atoms. The results showed that the adsorption energies of SO3 on the different nanoparticles following the order N-doped (N site)>N-doped ( O D site)>Undoped ( O D site). We provide the electronic structure of the nanoparticles, as well as complex systems containing the sulfur trioxide molecule and discuss the key issues that influence the adsorption process. The structural properties including the bond lengths, bond angles and adsorption energies and the electronic properties including the projected density of states (PDOSs) and molecular orbitals (MOs) have been mainly analyzed in detail. The obtained results indicate that the interaction between SO 3 molecule and N-doped TiO 2 nanoparticle is stronger than that between SO 3 and undoped nanoparticle, which suggests that N-doping helps to strengthen the interaction of SO 3 with TiO 2 anatase nanoparticles. It is shown that although SO 3 molecule has no significant interaction with undoped nanoparticle, it tends to be strongly adsorbed to N-doped anatase nanoparticles with considerable adsorption energies, being as an effective property to be utilized in gas sensing applications. We also note at this point that the titanium atom and the doped nitrogen atom sites are more active than the dangling oxygen site, which reveals that the titanium and doped nitrogen sites provide more stable adsorption geometries.

Multi switching behavior of hydrogen passivated silicene as molecular junction: A DFT-NEGF approach

Electron transport properties of pristine silicon-substituted analogue of pyrene, Si 16 H 8, and its carbon-doped analogue, Si 14 C 2 H 8, between two semi-infinite aluminum nanochain electrodes were investigated by means of density functional theory plus nonequilibrium green's function method. Here, the current-bias (I–Vb) characteristics were studied in the bias potential range of 0.0 up to 2.0 V in 0.1 V steps by imposing three gate voltages including -3.0, 0.0 and +3.0 V. The considerable result of the present study was the observation of multiple negative differential resistance (NDR) regions, suggesting that the studied systems could be used as nano-multi-switch. The I–Vb behavior of the studied systems along with the observation of the NDR's in each considered gate voltage was interpreted by means of transmission spectrum. These interpretations were carried on by the integration of the transmission spectrum in the corresponding bias window. The observed NDR characteristics including the bias range and current amplitude could be changed by the variations in the applied gate voltage. Controlling NDR characteristics of these devices using the variations of the gate voltage is a major advantage for practical purposes.

Study of thermodynamic properties of solution of ampicillin sodium in methanol at T = 298.15 k

Osmotic coefficients of the solution of Ampicillin sodium in methanol at T = 298.15 K were measured using the isopiestic technique and head space-gas chromatography. The experimental osmotic coefficients have been correlated using the ion interaction model of Pitzer, e-NRTL model of Chen, NRF and a fourth- order polynomial in terms of molality. In this work, reference solution is NaI-CH(3)OH. The vapor pressures of the solutions and the solvent activities have been calculated from the osmotic coefficients. Reliability of the models in expression of the osmotic coefficients were compared on the basis of standard deviation of the fittings. The best fit of experimental osmotic coefficients data have been obtained by the Pitzer based ion interaction model.