Nature of a Tetrabutylammonium Chloride-Levulinic Acid Deep Eutectic Solvent.

A deep eutectic solvent was formed by considering the mixtures of tetrabutylammonium chloride and levulinic acid, and it is studied via a combined theoretical and experimental approach. Physicochemical properties were measured as a function of temperature, providing a macroscopic characterization of the fluid. Quantum chemistry and classical molecular dynamics simulations were carried out for the nanoscopic characterization, providing attention to the nature, extension, and dynamics of the hydrogen bonding network, which is at the root of the properties of the fluid. The reported study allows multiscale characterization of this fluid as an archetypical example of a natural, low-cost, and sustainable fluid.

Molecular dynamics study on the interfacial properties of mixtures of monomers of polyvinylpyrrolidone (PVP)-based battery binders on graphene and graphite surfaces.

This study investigates the behavior of two different mixtures of monomers of polyvinylpyrrolidone (PVP)-based battery binders, polyvinylpyrrolidone:polyvinylidene difluoride (PVP:PVDF) and polyvinylpyrrolidone:polyacrylic acid (PVP:PAA), at graphene and graphite interfaces using classical molecular dynamics simulations. The aim is to identify the best performing monomer binder blend and carbon-based material for the design of battery-optimized energy devices. The PVP:PAA monomer binder blend and graphite are found to have the best interaction energies, densification upon adsorption, and more ordered structure. The adsorption of both monomer binder blends is strongly guided by the higher affinity of PVP and PAA monomeric molecules for the surfaces compared to PVDF. The structure of adsorbed layers of PVP:PVDF monomer binder blend on graphene and graphite develops more quickly than PVP:PAA, indicating faster kinetics. This study complements a previous density functional theory study recently reported by our group and contributes to a better understanding of the nanoscopic features of relevant interfacial regions involving mixtures of monomers of PVP-based battery binders and different carbon-based materials. The effect of a blend of commonly used monomer binders on carbon-based materials is essential for obtaining tightly bound anode and cathode active materials in lithium-ion batteries, which is crucial for designing battery-optimized energy devices.

Non-solvent post-modifications with volatile reagents for remarkably porous ketone functionalized polymers of intrinsic microporosity.

Chemical modifications of porous materials almost always result in loss of structural integrity, porosity, solubility, or stability. Previous attempts, so far, have not allowed any promising trend to unravel, perhaps because of the complexity of porous network frameworks. But the soluble porous polymers, the polymers of intrinsic microporosity, provide an excellent platform to develop a universal strategy for effective modification of functional groups for current demands in advanced applications. Here, we report complete transformation of PIM-1 nitriles into four previously inaccessible functional groups - ketones, alcohols, imines, and hydrazones - in a single step using volatile reagents and through a counter-intuitive non-solvent approach that enables surface area preservation. The modifications are simple, scalable, reproducible, and give record surface areas for modified PIM-1s despite at times having to pass up to two consecutive post-synthetic transformations. This unconventional dual-mode strategy offers valuable directions for chemical modification of porous materials.

A density functional theory based tight-binding study on the water effect on nanostructuring of choline chloride + ethylene glycol deep eutectic solvent.

The effect of water on the properties of an archetypical type III deep eutectic solvent [choline chloride : ethyleneglycol (1:2)] is analyzed using ab initio molecular dynamics simulations in the 0 to 60 wt. % water content range. The properties of the mixed fluids are studied considering nanostructuring, intermolecular forces (hydrogen bonding), the energy of interactions, dynamic properties, and domain analysis. The reported results confirm that the change in the properties of the studied deep eutectic solvent is largely dependent on the amount of water. The competing effect of water molecules for the available hydrogen bonding sites determines the evolution of the properties upon water sorption. The main structural features of the considered deep eutectic were maintained even for large water contents; thus, its hydrophilicity could be used for tuning fluid physicochemical properties.

Fluorescent Zn(II)-Based Metal-Organic Framework: Interaction with Organic Solvents and CO2 and Methane Capture.

Adsorption of carbon dioxide (CO2), as well as many other kinds of small molecules, is of importance for industrial and sensing applications. Metal-organic framework (MOF)-based adsorbents are spotlighted for such applications. An essential for MOF adsorbent application is a simple and easy fabrication process, preferably from a cheap, sustainable, and environmentally friendly ligand. Herein, we fabricated a novel structural, thermally stable MOF with fluorescence properties, namely Zn [5-oxo-2,3-dihydro-5H-[1,3]-thiazolo [3,2-a]pyridine-3,7-dicarboxylic acid (TPDCA)] • dimethylformamide (DMF) •0.25 H2O (coded as QUF-001 MOF), in solvothermal conditions by using zinc nitrate as a source of metal ion and TPDCA as a ligand easy accessible from citric acid and cysteine. Single crystal X-ray diffraction analysis and microscopic examination revealed the two-dimensional character of the formed MOF. Upon treatment of QUF-001 with organic solvents (such as methanol, isopropanol, chloroform, dimethylformamide, tetrahydrofuran, hexane), interactions were observed and changes in fluorescence maxima as well as in the powder diffraction patterns were noticed, indicating the inclusion and intercalation of the solvents into the interlamellar space of the crystal structure of QUF-001. Furthermore, CO2 and CH4 molecule sorption properties for QUF-001 reached up to 1.6 mmol/g and 8.1 mmol/g, respectively, at 298 K and a pressure of 50 bars.

A theoretical study on CO2 at Li4SiO4 and Li3NaSiO4 surfaces.

Lithium silicates have attracted great attention in recent years due to their potential use as high-temperature (450-700 °C) sorbents for CO2 capture. Lithium orthosilicate (Li4SiO4) can theoretically adsorb CO2 in amounts up to 0.36 g CO2 per g Li4SiO4. The development of new Li4SiO4-based sorbents is hindered by a lack of knowledge of the mechanisms ruling CO2 adsorption on Li4SiO4, especially for eutectic mixtures. In this work, the structural, electronic, thermodynamic and CO2 capture properties of monoclinic phases of Li4SiO4 and a binary (Li3NaSiO4) eutectic mixture are investigated using density functional theory. The properties of the bulk crystal phases as well as of the relevant surfaces are analysed. Likewise, the results for CO2-lithium silicates indicate that CO2 is strongly adsorbed on the oxygen sites of both sorbents through chemisorption, causing an alteration not only in the chemical structure and atomic charges of the gas, as reflected by both the angles and bond distances as well as atomic charges, but also in the cell parameters of the Li4SiO4 and Li3NaSiO4 systems, especially in Li4SiO4(001) and Li3NaSiO4(010) surfaces. The results confirm strong adsorption of CO2 molecules on all the considered surfaces and materials followed by CO2 activation as inferred from CO2 bending, bond elongation and surface to CO2 charge transfer, indicating CO2 chemisorption for all cases. The Li4SiO4 and Li3NaSiO4 surfaces may be proposed as suitable sorbents for CO2 capture in wide temperature ranges.

Insights on novel type V deep eutectic solvents based on levulinic acid.

Type V natural deep eutectic solvents considering menthol, thymol, and levulinic acids are studied considering a combined experimental and theoretical approach to develop a multiscale characterization of these fluids with particular attention to intermolecular forces (hydrogen bonding) and their relationships with macroscopic behavior. Density, viscosity, refraction index, and thermal conductivity were measured as a function of temperature, providing a thermophysical characterization of the fluids. Quantum chemistry was applied to characterize hydrogen bonding in minimal molecular clusters, allowing us to quantify interaction strength, topology (according to atoms in a molecule theory), and electronic properties. Classical molecular dynamics simulations were also performed, allowing us to characterize bulk liquid phases at the nanoscopic level, analyzing the fluid's structuring, void distribution, and dynamics. The reported results allowed us to infer nano-macro relationships, which are required for the proper design of these green solvents and their application for different technologies.

Nanostructuring and macroscopic behavior of type V deep eutectic solvents based on monoterpenoids.

Type V natural deep eutectic solvents based on monoterpenoids (cineole, carvone, menthol, and thymol) are studied using a combined experimental and molecular modeling approach. The reported physicochemical properties showed low viscous fluids whose properties were characterized as a function of temperature. The theoretical study combining quantum chemistry and classical molecular dynamics simulations provided a nanoscopic characterization of the fluids, particularly for the hydrogen bonding network and its relationship with the macroscopic properties. The considered fluids constitute a suitable type of solvents considering their properties, cost, origin, and sustainability in different technological applications and sow the possibility of developing type V NADES from different types of molecules, especially in the terpenoid family of compounds.

Nanoscopic study on carvone-terpene based natural deep eutectic solvents.

Terpene-based natural deep eutectic solvents (NADES) formed by using carvone as the hydrogen bond acceptor and a series of organic acids including tartaric, succinic, malic, and lactic acids as hydrogen bond donors are studied using a combination of molecular simulation methods. Density functional theory was used to study small molecular clusters and the topological characterization of the intermolecular forces using the atoms-in-a-molecule approach. Close-range interactions between the optimized carvone bases eutectic solvents between carbon dioxide have been studied for potential utilization of these solvents for gas capture purposes. Furthermore, COSMO-RS calculations have been carried out for the carbon dioxide solubilization performance of NADES compounds and to obtain s-profiles to infer the polarity and H-bond forming ability of the studied solvents. On the other hand, molecular dynamics simulations were carried out to analyze the bulk liquid properties and their relationship with relevant macroscopic properties (e.g., density or thermal expansion). Last but not least, relevant toxicity properties of the studied systems were predicted and reported in this work. The reported results provide the characterization of environmentally friendly NADES and show the suitability of carvone for advanced applications as carbon dioxide solubilizers.

Theoretical insights into the cineole-based deep eutectic solvents.

Deep eutectic solvents based on cineole as hydrogen bond acceptors and organic acids (succinic, malic, and lactic) as hydrogen bond donors are studied using a theoretical approach. The nature, strength, and extension of hydrogen bonding are analyzed, thus quantifying this prevailing interaction and its role in the fluid properties. Density functional theory was used to study small molecular clusters, and the topological characterization of the intermolecular forces was carried out using atoms in a molecule theory. Classical molecular dynamics simulations were considered to study nanoscopic bulk liquid properties and their relationship with relevant macroscopic properties such as density or thermal expansion. The reported results provide the characterization of environmentally friendly deep eutectic solvents and show the suitability of cineole for developing these sustainable materials.

Insights on (C, BN, Si, Ge, MoS2) Nanotubes in Reline Deep Eutectic Solvent.

The properties of carbon, boron nitride, silicon, germanium, and molybdenum disulfide nanotubes in reline (cholinium chloride + urea) deep eutectic solvents were studied by using classical molecular dynamics simulations. These nanotubes + reline nanofluids provide a suitable platform for the development of sustainable thermal engineering applications. The reported results lead to the characterization of nanotube solvation and reline layering around the nanotube surfaces as well as the behavior of reline upon confinement inside the considered nanotube cavities. Changes in reline hydrogen bonding in the presence of the nanotubes are also analyzed and related with the development of stable nanotube dispersions, thus showing reline as a suitable vehicle for nanotubes.

Theoretical Study on Deep Eutectic Solvents as Vehicles for the Delivery of Anesthetics.

The solvation and solubilization of selected anesthetic active pharmaceutical ingredients (bupivacaine, prilocaine, and procaine) in arginine-based deep eutectic solvents are studied using a theoretical approach considering quantum chemistry and classical molecular dynamics. The intermolecular forces between the anesthetics and the solvent are characterized, with particular attention to hydrogen bonding, in terms of strength, topological properties, interaction mechanism, structuring, and dynamic properties of solvation shells. The reported results show the nanoscopic properties that confirm these solvents as suitable materials for anesthetics drug delivery in the liquid phase.

Deep Eutectic Solvent Reline at 2D Nanomaterial Interfaces.

The behavior of reline (choline chloride mixed with urea at a 1-to-2 mole ratio) deep eutectic solvent at the interfaces of 2D nanomaterials was studied by using molecular simulation methods. Graphene, boron nitride, silicene, germanene, and molybdenum disulfide were studied for considering the most relevant features of available 2D nanomaterials. The reline-nanomaterial interactions were analyzed, and the mechanism of reline adsorption with the properties at the interfaces was studied. Likewise, the behavior of the deep eutectic solvent upon confinement between parallel nanosheets was considered as a model of properties when placed in slit nanopores. The results provide a nanoscopic vision of the adsorption and confinement of reline regarding 2D nanomaterials, thus advancing the development of new materials based on deep eutectics.

Quantum Chemistry Insight into the Interactions Between Deep Eutectic Solvents and SO2.

A systematic research work on the rational design of task specific Deep Eutectic Solvents (DES) has been carried out via density functional theory (DFT) in order to increase knowledge on the key interaction parameters related to efficient SO2 capture by DES at a molecular level. A total of 11 different DES structures, for which high SO2 affinity and solubility is expected, have been selected in this work. SO2 interactions in selected DES were investigated in detail through DFT simulations and this work has generated a valuable set of information about required factors at the molecular level to provide high SO2 solubility in DES, which is crucial for enhancing the current efficiency of the SO2 capture process and replacing the current state of the art with environmentally friendly solvents and eventually implementing these materials in the chemical industry. Results that were obtained from DFT calculations were used to deduce the details of the type and the intensity of the interaction between DES and SO2 molecules at various interaction sites as well as to quantify short-range interactions by using various methods such as quantum theory of atoms in a molecule (QTAIM), electrostatic potentials (ESP) and reduced density gradients (RDG). Systematic research on the molecular interaction characterization between DES structures and SO2 molecule increases our knowledge on the rational design of task-specific DES.

Design of arginine-based therapeutic deep eutectic solvents as drug solubilization vehicles for active pharmaceutical ingredients.

The solvation of lidocaine in three newly designed deep eutectic solvents is studied using combined experimental and theoretical methods that include density functional theory and molecular dynamics methods. The intermolecular forces between lidocaine and the hydrogen bond acceptors and hydrogen bond donors of the deep eutectic solvents were analysed regarding the type and the strength of inter- and intra-molecular bonding. The structure, composition and properties of the lidocaine solvation shells are analysed together with the possible lidocaine-clustering around the studied deep eutectic solvents and their constituent molecules. Furthermore, the changes in the solvent structures upon lidocaine solubilization are also studied. Natural product-based eutectic solvents showed considerably high solvation of lidocaine in all three deep eutectics based on the strong solute-solvent intermolecular interactions accompanied by a slight volume expansion and minor solvent structural changes. These non-toxic and almost null-volatile therapeutic deep eutectic solvents can be considered as suitable solubilization media for developing pharmaceutical applications and they can be considered as effective drug delivery vehicles for active pharmaceutical ingredients.

Permeabilities of CO2, H2S and CH4 through Choline-Based Ionic Liquids: Atomistic-Scale Simulations.

Molecular dynamics simulations are used to study the transport of CO 2 , H 2 S and CH 4 molecules across environmentally friendly choline-benzoate and choline-lactate ionic liquids (ILs). The permeability coefficients of the considered molecules are calculated using the free energy and diffusion rate profiles. Both systems show the largest resistance to CH 4 , whereas more than 5 orders of magnitude larger permeability coefficients are obtained for the other two gas molecules. The CO 2 /CH 4 and H 2 S/CH 4 selectivity was estimated to be more than 10 4 and 10 5 , respectively. These results indicate the great potential of the considered ILs for greenhouse gas control.

A theoretical study on lidocaine solubility in deep eutectic solvents.

The solvation of lidocaine in two selected deep eutectic solvents is studied using density functional theory and molecular dynamics methods. The intermolecular forces between lidocaine and the involved molecules are analysed in terms of van der Waals and hydrogen bond interactions. The structure, composition and properties of the lidocaine solvation shells are analysed together with the possible lidocaine clustering. The changes in the solvent structures upon lidocaine solution are also studied. The reported results show that the effective solvation of lidocaine in deep eutectics is because of strong solute-solvent intermolecular interactions accompanied by a slight volume expansion and minor solvent structural changes, thus confirming deep eutectics as suitable media for developing pharmaceutical applications.

A theoretical study on mixtures of amino acid-based ionic liquids.

Ionic liquid mixtures containing amino acid anions are studied at the microscopic level using molecular dynamics simulations. The analysis of relevant features such as intermolecular forces (hydrogen bonding), molecular level arrangements, and properties of solvation spheres, allowed inferring the structuring of the studied mixtures. The effects of mixture compositions and the number of cations and anions were analysed in detail. The reported results showed even distribution of anions around cations. The absence of microheterogeneities and low deviations from ideality are due to the similar mechanism of interaction between the considered anions and cations. Likewise, the most relevant features are produced by the development of hydrogen bonding between the amino acid carboxylate group and hydrogen bond donor sites in the cations.

Molecular Modeling Analysis of CO2 Absorption by Glymes.

The properties of diglyme + CO2 systems were analyzed through density functional theory and molecular dynamics methods with the objective of inferring the microscopic properties of CO2 capture by glyme-based solvents and the effect of ether group regarding solvents affinity toward CO2. Calculations of diglyme + CO2 molecular clusters using density functional theory allowed accurate quantification and characterization of short-range intermolecular forces between these molecules, whereas the molecular dynamics simulation of diglyme + CO2 liquid mixtures, for different CO2 contents, were the means to infer the properties and dynamics of bulk liquid phases upon CO2 absorption. Likewise, liquid diglyme + CO2 gas interfaces were also studied using molecular dynamics methods to examine the kinetics of CO2 capture, adsorption at the gas-liquid interface, and the mechanism of interface crossing, which is of pivotal importance for the design of CO2 capturing units.