scholarly journals Pyr1,xTFSI Ionic Liquids (x = 1–8): A Computational Chemistry Study

2020 ◽  
Vol 10 (23) ◽  
pp. 8552
Author(s):  
Sergio Brutti
Keyword(s):  
Ionic Liquids ◽  
Physicochemical Properties ◽  
Density Functional ◽  
Ion Pairs ◽  
Molecular Size ◽  
Molecular Structures ◽  
Safety Standards ◽  
Oxidation Reduction ◽  
Reduction Stability ◽  
The Impact

Pyrrolidinium-based (Pyr) ionic liquids are a very wide family of molecular species. Pyrrolidinium cations are electrochemically stable in a large potential interval and their molecular size hinders their transport properties. The corresponding ionic liquids with trifluoromethyl sulphonyl imide anions are excellent solvents for lithium/sodium salts and have been demonstrated as electrolytes in aprotic batteries with enhanced safety standards. In this study, the analysis of the physicochemical properties of a homologous series of pyrrolidinium-based ionic liquids with general formula Pyr1,xTFSI (x = 1–8) have been tackled by first principles calculations based on the density functional theory. The molecular structures of isolated ions and ion pairs have been predicted by electronic structure calculations at B3LYP level of theory in vacuum or in simulated solvents. Thermodynamic properties have been calculated to evaluate the ion pairs dissociation and oxidation/reduction stability. This is the first systematic computational analysis of this series of molecules with a specific focus on the impact of the length of the alkyl chain on the pyrrolidinium cation on the overall physicochemical properties of the ion pairs.

scholarly journals Combinations of Freeze-Dried Amorphous Vardenafil Hydrochloride with Saccharides as A Way to Enhance Dissolution Rate and Permeability

2021 ◽  
Vol 14 (5) ◽  
pp. 453
Author(s):  
Gabriela Wiergowska ◽  
Dominika Ludowicz ◽  
Kamil Wdowiak ◽  
Andrzej Miklaszewski ◽  
Kornelia Lewandowska ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Density Functional ◽  
Hydroxypropyl Methylcellulose ◽  
Fold Increase ◽  
Crystalline Form ◽  
Amorphous Form ◽  
Freeze Dried ◽  
Apparent Solubility ◽  
Gastrointestinal Epithelium ◽  
The Impact

To improve physicochemical properties of vardenafil hydrochloride (VAR), its amorphous form and combinations with excipients—hydroxypropyl methylcellulose (HPMC) and β-cyclodextrin (β-CD)—were prepared. The impact of the modification on physicochemical properties was estimated by comparing amorphous mixtures of VAR to their crystalline form. The amorphous form of VAR was obtained as a result of the freeze-drying process. Confirmation of the identity of the amorphous dispersion of VAR was obtained through the use of comprehensive analysis techniques—X-ray powder diffraction (PXRD) and differential scanning calorimetry (DSC), supported by FT-IR (Fourier-transform infrared spectroscopy) coupled with density functional theory (DFT) calculations. The amorphous mixtures of VAR increased its apparent solubility compared to the crystalline form. Moreover, a nearly 1.3-fold increase of amorphous VAR permeability through membranes simulating gastrointestinal epithelium as a consequence of the changes of apparent solubility (Papp crystalline VAR = 6.83 × 10−6 cm/s vs. Papp amorphous VAR = 8.75 × 10−6 cm/s) was observed, especially for its combinations with β-CD in the ratio of 1:5—more than 1.5-fold increase (Papp amorphous VAR = 8.75 × 10−6 cm/s vs. Papp amorphous VAR:β-CD 1:5 = 13.43 × 10−6 cm/s). The stability of the amorphous VAR was confirmed for 7 months. The HPMC and β-CD are effective modifiers of its apparent solubility and permeation through membranes simulating gastrointestinal epithelium, suggesting a possibility of a stronger pharmacological effect.

Density Functional Theory Study on the Absorption of CO2 by the Ionic Liquid of 1-butyl-3-methylimidazolium Acetate

2013 ◽  
Vol 807-809 ◽  
pp. 543-548 ◽  
Author(s):  
Yan Fei Chen ◽  
Yan Hong Cui ◽  
Dong Shun Deng ◽  
Ning Ai
Keyword(s):  
Density Functional Theory ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Density Functional ◽  
Ion Pairs ◽  
Ion Pair ◽  
Frontier Molecular Orbitals ◽  
Density Functional Theory Study ◽  
Electronic Density ◽  
Functional Theory

The absorptions of CO2on the 1-butyl-3-methylimidazolium acetate ([Bmi [Ac]) with different substituents are calculated systematically at GGA/PW91 level. Three hydrogen bonds are formed between [A and cations of 1-n-[Bmi [A ([NBmi+) and 1-tert-[Bmi [A ([TBmi+). The interaction between CO2and the [NBmi [A by a C-O bond is much weaker than that with the [TBmi [A by forming a O...O...C...C four member-ring. The chemisorption of CO2on the ion pairs of [NBmi [A is much weaker than that on the [TBmi [A, resulted from the absorption energies analysis. The frontier molecular orbitals shows the electronic density overlap between absorbed CO2and the [A in CO2-[NBmi [A is much weaker than that in [TBmi [A. Therefore, the chemisorption of CO2on the ion pair of [NBmi [A is much weaker than that on the [TBmi [A. The ionic liquids based [NBmi+can be used repetitively, and the adsorbed CO2would be easier desorbed.

scholarly journals Astrochemical relevance of VUV ionization of large PAH cations

2020 ◽  
Vol 641 ◽  
pp. A98 ◽  
Author(s):  
G. Wenzel ◽  
C. Joblin ◽  
A. Giuliani ◽  
S. Rodriguez Castillo ◽  
G. Mulas ◽  
...  
Keyword(s):  
Cross Sections ◽  
Density Functional ◽  
Interstellar Dust ◽  
Vacuum Ultraviolet ◽  
Branching Ratio ◽  
Molecular Size ◽  
Photoelectric Effect ◽  
Interstellar Gas ◽  
Ionization Cross Sections ◽  
The Impact

Context. As part of interstellar dust, polycyclic aromatic hydrocarbons (PAHs) are processed by an interaction with vacuum ultraviolet (VUV) photons emitted by hot stars. This interaction leads to the emission of not only the well-known aromatic infrared bands, but also electrons, which can significantly contribute to the heating of the interstellar gas. Aims. Our aim is to investigate the impact of molecular size on the photoionization properties of cationic PAHs. Methods. Trapped PAH cations of sizes between 30 and 48 carbon atoms were submitted to VUV photons in the range of 9–20 eV from the DESIRS beamline at the synchrotron SOLEIL. All resulting photoproducts including dications and fragment cations were mass-analyzed and recorded as a function of photon energy. Results. Photoionization is found to be predominant over dissociation at all energies, which differs from the conclusions of an earlier study on smaller PAHs. The photoionization branching ratio reaches 0.98 at 20 eV for the largest studied PAH. The photoionization threshold is observed to be between 9.1 and 10.2 eV, in agreement with the evolution of the ionization potential with size. Ionization cross sections were indirectly obtained and photoionization yields extracted from their ratio with theoretical photoabsorption cross sections, which were calculated using time-dependent density functional theory. An analytical function was derived to calculate this yield for a given molecular size. Conclusions. Large PAH cations could be efficiently ionized in H I regions and contribute to the heating of the gas by the photoelectric effect. Also, at the border of or in H II regions, PAHs could be exposed to photons of energy higher than 13.6 eV. Our work provides recipes to be used in astronomical models to quantify these points.

THEORETICAL STUDY ON INTERACTION BETWEEN IONIC LIQUIDS AND AROMATIC SULFUR COMPOUNDS

2011 ◽  
Vol 10 (01) ◽  
pp. 31-40 ◽  
Author(s):  
YI NIE ◽  
XIANGAI YUAN
Keyword(s):  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Density Functional ◽  
Sulfur Compound ◽  
Ion Pairs ◽  
Benzene Molecule ◽  
Sulfur Compounds ◽  
Functional Theory ◽  
Hydrogen Bonding Interactions ◽  
Bonding Interaction

It is important to understand how ionic liquids interact with aromatic sulfur compounds in view of ionic liquids application in desulfurization from fuels. Ion pairs of N, N-dialkylimidazolium dialkylphosphate ionic liquids were optimized at the Becke3LYP level of density functional theory. The most stable geometries were obtained. The stable ion pairs indicate there exist hydrogen bonding interactions between them. The calculated interaction energies of ion pairs were found to increase in magnitude with decreasing alkyl chain length, and with decreasing anionic radius. Furthermore, the interactions between the IL and aromatic sulfur compound, and benzene molecule were investigated. The results indicate that there exist hydrogen bonds between them. The calculated interaction energy between IL and sulfur compound is larger than that between IL and benzene. The aromatic ring π - π interaction and hydrogen bonding interaction may be the dominant factors to influence the trend of interaction between ILs and aromatic sulfur compounds.

scholarly journals Ionic Liquids as High-Performance Lubricants and Lubricant Additives

2021 ◽  
Author(s):  
Hong Guo ◽  
Patricia Iglesias Victoria
Keyword(s):  
Ionic Liquids ◽  
Physicochemical Properties ◽  
High Performance ◽  
Negative Impact ◽  
Molecular Structures ◽  
Lubricant Additives ◽  
Friction Reduction ◽  
Protic Ionic Liquids ◽  
Protection Mechanisms ◽  
Low Toxicity

Taking into account the environmental awareness and ever-growing restrictive regulations over contamination, the study of new lubricants or lubricant additives with high performance and low toxicity over the traditional lubes to reduce the negative impact on the environment is needed. In this chapter, the current literature on the use of ionic liquids, particularly protic ionic liquids, as high-performance lubricants and lubricant additives to different types of base lubricants are reviewed and described. The relation between ionic liquids structures and their physicochemical properties, such as viscosity, thermal stability, corrosion behavior, biodegradability, and toxicity, is elaborated. Friction reduction and wear protection mechanisms of the ionic liquids are discussed with relation to their molecular structures and physicochemical properties.

scholarly journals RHF and DFT Study of the Molecular and Electronic Properties of (SiO2)n and (GeO2)n Nanoclusters

2018 ◽  
Vol 12 (9) ◽  
pp. 108 ◽  
Author(s):  
Chifu E. Ndikilar ◽  
L. S. Taura ◽  
G. W. Ejuh ◽  
A. Muhammad
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Research Work ◽  
Molecular Size ◽  
Germanium Dioxide ◽  
Molecular Structures ◽  
Plane Symmetric ◽  
Hartree Fock ◽  
Advantages And Disadvantages ◽  
Silicon And Germanium

The study of nanoclusters has attracted a lot of scientific research over the years. This class of materials are important because they bridge the gap between bulk materials and molecular structures. Silicon and Germanium oxides have many applications in semiconductor technology and nanotechnology. In this research work, molecular and electronic properties of Silicon and Germanium dioxide nanoclusters are studied. The results obtained reveal the comparative advantages and disadvantages of using any of the two oxides for particular applications. Restricted Hartree Fock and Density Functional Theory computations of the molecular and electronic properties of (SiO2)n and (GeO2)n nanoclusters (n = 1,..,6) are studied. Silicon dioxide clusters are found to have higher thermal energies and lower average bond lengths and are thus more stable than Germanium dioxide clusters. At n = 1, both nanoclusters are non-polar, but gradually become more polar with increase in n. The average polarizability, molecular hyperpolarizability and total thermal energies of the nanoclusters increases with increase in molecular size. Computed values of the electron affinities for (SiO2)n clusters agree with experimental results. Some of the most intense Infra Red vibrational motions observed in both molecules are anti-symmetric stretching of Si=O/Ge-O and chain in plane, symmetric stretching of the Si=O/Ge-O bonds and chain in plane and symmetric twisting/breathing of the chain(s) in plane. The two nanoclusters are also Raman active at some frequencies.

scholarly journals Electronic structural properties of amino/hydroxyl functionalized imidazolium-based bromide ionic liquids

2020 ◽  
Vol 18 (1) ◽  
pp. 576-583
Author(s):  
Xiaoling Hu ◽  
Xingang Jia ◽  
Kehe Su ◽  
Xuefan Gu
Keyword(s):  
Ionic Liquids ◽  
Structural Properties ◽  
Density Functional ◽  
Energy Levels ◽  
Ion Pairs ◽  
Binding Energies ◽  
Intramolecular Interactions ◽  
Quantum Chemical Descriptors ◽  
Functional Theory ◽  
Chemical Descriptors

AbstractElectronic structural properties of the three different imidazolium-based ionic liquids, namely, 1-butyl-3-methyl imidazolium bromide (C4mimBr), 1-(4-hydroxybutyl)-3-methylimidazolium bromide (C4OHmimBr), and 1-(4-aminobutyl)-3-methylimidazolium bromide (C4NH2mimBr), were investigated with density functional theory at the B3LYP/6-311++G(d,p) level. The conformations of the mentioned cations were fully studied first using CONFLEX 8.A program. The quantum theory of atoms in molecules was used to investigate the nature of intramolecular interactions. The counterpoise-corrected ion pairs binding energies were obtained at the same level of theory. Natural bond orbital analyses show that the largest intra-molecular interaction comes from the orbital overlap between n(N1) and π* (N4–C5) in the mentioned compounds. The energy levels of frontier molecular orbitals (FMOs) are displayed. The global quantum chemical descriptors are also calculated based on the energy values of FMOs.

DFT study of the physicochemical properties of A- and B-type procyanidin oligomers

2016 ◽  
Vol 15 (08) ◽  
pp. 1650069 ◽  
Author(s):  
Ana María Mendoza-Wilson ◽  
Francisco Javier Carmelo-Luna ◽  
Humberto Astiazarán-García ◽  
Bertha I. Pacheco-Moreno ◽  
Iván Anduro-Corona ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Density Functional ◽  
Molecular Size ◽  
Potential Effect ◽  
Degree Of Polymerization ◽  
Hydroxyl Groups ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Hydrophilic Character ◽  
Pass Through

The objective of this study was to determine the physicochemical properties of the oligomers of procyanidins (PCs) including PA1, PA2, PB1, PB2, PC1 and a B-type tetramer, taking into account of their conformations related to the interflavan links using the density functional theory (DFT). This information may provide useful insight into the potential effect of physicochemical properties on the absorption of PCs. The results indicate that A-type and B-type PCs in all of their conformations tend to be more stable in water than in octanol, showing a hydrophilic character due to their negative log [Formula: see text] values, which increase with the degree of polymerization (DP). The studied PCs, including the B-type tetramer, can achieve an appropriate molecular size (i.e. width and length) that can allow them to pass through the pores in the paracellular route in the human small intestine. The factor that could limit the absorption of the PC oligomers with increases in size is the higher number of hydroxyl groups exposed to the outside of the molecule due to their potential to interact with other molecules, which is based on electrostatic potential maps.

scholarly journals TransfersomILs: From Ionic Liquids to a New Class of Nanovesicular Systems

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 7
Author(s):  
Ana Júlio ◽  
João Guilherme Costa ◽  
Catarina Pereira-Leite ◽  
Tânia Santos de Almeida
Keyword(s):  
Ionic Liquids ◽  
Physicochemical Properties ◽  
Colloidal Stability ◽  
Storage Stability ◽  
Pharmaceutical Formulations ◽  
Controlled Delivery ◽  
New Class ◽  
Improved Performance ◽  
And Performance ◽  
The Impact

Ionic liquids (ILs) have increasingly been studied as key materials to upgrade the performance of many pharmaceutical formulations. In controlled delivery systems, ILs have improved multiple physicochemical properties, showing the relevance of continuing to study their incorporation into these formulations. Transfersomes are biocompatible nanovesicular systems, quite useful in controlled delivery. They have promising characteristics, such as elasticity and deformability, making them suitable for cutaneous delivery. Nonetheless, their overall properties and performance may still be improved. Herein, new TransfersomILs systems to load rutin were developed and the physicochemical properties of the formulations were assessed. These systems were prepared based on an optimized formulation obtained from a Box–Behnken factorial design (BBD). The impact of imidazole-based ILs, cholinium-based ILs, and their combinations on the cell viability of HaCaT cells and on the solubility of rutin was initially assessed. The newly developed TransfersomILs containing rutin presented a smaller size and, in general, a higher association efficiency, loading capacity, and total amount of drug release compared to the formulation without IL. The ILs also promoted the colloidal stability of the vesicles, upgrading storage stability. Thus, ILs were a bridge to develop new TransfersomILs systems with an overall improved performance.

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