Theoretical Study on Amino Acid-Based Ionic Pairs and Their Interaction with Carbon Nanostructures

Quantum chemistry methods were used to analyze the properties of ionic pairs formed by combination of the 1-ethyl-3-methylimidazolium cation with anions derived from alanine, glycine, serine, and phenylalanine amino acids, which appear in the corresponding ionic liquids. Anion–cation pairs were studied from structural and energetic viewpoints using density functional theory together with the use of natural bond orbital and atoms in a molecule approaches. Interactions of the mentioned ionic pairs with carbon nanostructures carried out with graphene sheets and single-walled carbon nanotubes, with ions placed on the outer surface and when confined inside the nanotube, were analyzed from first principles. Interaction energies, density of states, and charge density allow inferring the mechanism of interaction between the ion pairs and graphene or carbon nanotubes

Physicochemical Insights on Alkylcarbonate–Alkanol Solutions

Macroscopic properties and structuring at the molecular level of dialkylcarbonate + 1-alkanol mixed fluids have been studied as a function of alkyl chain lengths in 1-alkanol and dialkylcarbonate, mixture composition, and temperature. A combined experimental and computational approach was considered for studying the relationships between the nanoscopic structure of the mixed fluids; nature, extension, and organization of hydrogen bonding; and physicochemical properties. Thermodynamics characterization, using excess and mixing properties, are related with the strength and characteristics of intermolecular forces. Classic molecular dynamics simulations and quantum chemistry calculations provide a detailed picture of the mixed fluids’ structuring and dynamic behavior

On the Viscosity of Pyridinium Based Ionic Liquids: An Experimental and Computational Study

A study on the viscosity of eight pyridinium based ionic liquids is reported for wide pressure and temperature ranges. Measurements were performed using an electromagnetic moving piston viscometer. Experimental data were fitted to a Tait-like equation demonstrating good correlations, which was used to calculate pressure/viscosity and temperature/viscosity coefficients. The effect of the involved anions and cation on the ionic liquid viscosity was analyzed from a molecular viewpoint using hole theory, quantum chemistry calculations using density functional theory, and classical molecular dynamics simulations. The analysis of the experimental and computational results shows the complex effects controlling viscosity of studied fluids, including strength of ionic pairs, molecular sizes, and mobility and effects rising from the availability and cavity sizes distributions in pyridinium-based ionic liquids

Theoretical Study of Amino Acid-Based Ionic Liquids Interacting with Carbon Nanosystems

The properties of 1-ethyl-3-methylimidazolium glycinate ionic liquid regarding fullerenes, graphene, and single-walled carbon nanotubes are studied using classical molecular dynamics simulations. Endohedral fullerenes forming C60 to C540 containing a variable number of confined ions are studied, and the solvation of these systems by bulk liquid phases is also studied. The adsorption of the ionic liquid on top of graphene sheets and the confinement between two sheets are also analyzed as a function of intersheet separation. Likewise, confinement inside single-walled nanotubes as a function of nanotube diameter is analyzed together with ionic mobility in comparison with bulk phases. External solvation, densification, and layering around the nanotubes are also considered. The properties of these systems involving amino acid-based ionic liquids are compared with available studies involving classical imidazolium ionic liquids with other types of ions

Insights into Glycol Ether–Alkanol Mixtures from a Combined Experimental and Theoretical Approach

The binary liquid mixtures of glycol ethers (glymes) + 1-alkanol were characterized from the microscopic and macroscopic viewpoints through a combined experimental and theoretical study. Structuring, dynamics, and intermolecular forces were determined using density functional theory and classical molecular dynamics methods. The macroscopic behavior was studied though the measurement of relevant physicochemical properties and Raman IR studies. The changes in intermolecular forces with mixture composition, temperature, and the effects from the types of glymes as well as 1-alkanols were considered. Hydrogen bonding in the mixed fluids, its changes upon mixing, and mixture composition showed a large effect on fluids’ structure and determined most of the fluids’ properties together with the presence of hydrophobic domains from long 1-alkanols

Characterization of Amide–Alkanediol Intermolecular Interactions

The properties of formamide + 1,2-alkanediol binary liquid systems were studied both at the macro- and microscopic levels using a combined experimental and computational methodology. Physicochemical properties, infrared spectroscopy, and solvatochromic studies together with classic molecular dynamics and quantum chemistry calculations allowed the main characteristics of these binary fluids to be inferred with regard to the variations of hydrogen bonding with formamide and 1,2-alkanediol molecular structures, mixture composition, and temperature. The complexity of these liquid systems arising from the presence of three different functional groups, which may act as hydrogen bond donors and acceptors, is analyzed, allowing a detailed picture to be inferred of the studied systems which is of relevance both for basic liquid state theory and for industrial purposes

Structure of Alkylcarbonate + <i>n</i>‑Alkane Mixed Fluids

The properties of dialkylcarbonate + <i>n</i>-alkane mixed fluids were studied both from macroscopic and from microscopic viewpoints using thermophysical measurements combined with classic molecular dynamics simulations and DFT quantum chemistry studies. The objective of this study is a whole range characterization of dialkylcarbonate-containing systems as fuel oxygenated additives. The reported results allowed analyzing the structure, dynamics, and intermolecular forces in these systems as a function of composition and temperature, paying attention to the mechanism of carbonate–<i>n</i>-alkane interaction for understanding the role of dialkylcarbonates in fuel properties