The nature of flavonoids in polar organic solvents solutions is studied using classical molecular dynamics simulations considering quercetin as an archetypical flavonoid and acetone, dimethylformamide and dimethyl sulfoxide as representatives of solvents with different polarity. The solvation, intermolecular forces (hydrogen bonding) and interactions of the flavonoid with the solvents are analyzed. Likewise, the role of quercetin on changing the solvent properties and the possibility of acting as a solubility enhancer for fullerenes (C60) are studied by considering the properties of C60 fullerene in quercetin plus polar solvents solutions. The reported results provide information on the nature of the considered complex liquid mixtures and analyze the possibility of using flavonoids as natural, non-toxic, modifiers of traditional polar organic solvents and to improve the solubility of complex solutes such as fullerene nanoparticles. [link]

Adsorbed natural gas (ANG) technology is a viable alternative to conventional liquefied or compressed natural-gas storage. Many different porous materials have been considered for adsorptive, reversible methane storage, but fall short of the US Department of Energy targets (0.5 g g⁻¹, 263 l l⁻¹). Here, we prepare a flexible porous polymer, made from benzene and 1,2-dichloroethane in kilogram batches, that has a high methane working capacity of 0.625 g g⁻¹ and 294 l l⁻¹ when cycled between 5 and 100 bar pressure. We suggest that the flexibility provides rapid desorption and thermal management, while the hydrophobicity and the nature of the covalently bonded framework allow the material to tolerate harsh conditions. The polymer also shows an adsorbate memory effect, where a less adsorptive gas (N₂) follows the isotherm profile of a high-capacity adsorbate (CO₂), which is attributed to the thermal expansion caused by the adsorption enthalpy. The high methane capacity and memory effect make flexible porous polymers promising candidates for ANG technology.

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In this manuscript, we report synthesis, characterization and application of amine and amide type covalent organic frameworks as CO₂ adsorbent materials at various isotherms and wide pressure conditions. Furthermore, we also report a detailed density functional theory investigation of the studied adsorbents in order to explain their adsorption behaviors and provide comparisons with experimental results. The objective of this work was to investigate custom design porous polymers by building amine and amide functionalities in the final structures, whether they have efficient CO₂ capturing performances at wide process conditions that covers both low and high pressure end applications to cover either pre- or post-combustion processes. On the other hand, energy storage performances of these materials were tested by performing H₂ sorption experiments as well. Two porous polymers, namely COP-9 and COP-10, were characterized with BET, TGA and FTIR to evaluate the physical properties of studied porous polymers and then were tested for CO₂, N₂ and H₂ adsorption both at low and high pressures. Studied materials were found to have compelling adsorption capacity mostly at high pressures and have very good selectivity for CO₂/N₂ and CO₂/H₂ respectively.

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In this paper, we report high pressure experimental measurements and detailed density functional theory (DFT) as well as molecular dynamic (MD) simulations of methane (CH₄) solubility in natural deep eutectic solvents (NADESs) that were prepared by using alanine (Al), betaine (Be), and choline chloride (ChCl) used as hydrogen bond acceptors (HBA) and lactic acid (La), malic acid (Ma), and phenylacetic acid (Paa) used as hydrogen bond donors (HBD). Experiments were performed on Al:La, Be:La, ChCl:La, ChCl:Ma, and ChCl:Paa systems up to 50 bar at 298.15 K. Meanwhile, this work includes the quantum theory of atoms in molecules (QTAIM) calculations that allow quantifying and characterizing the short-range interactions of studied systems, which is reported for the first time for NADESs and CH₄ interactions. Furthermore, MD simulations shed light onto the characteristics of intermolecular forces, particularly for hydrogen bonding, molecular arrangements in the liquid phases, and their role in fluid’s properties. The presented results showed that the studied NADESs can be used for selective CO₂/CH₄ separation in gas processing applications.

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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.

You can access this article published in the special issue of Molecules from this link.

Natural deep eutectic solvent that is formed by choline chloride and lactic acid is studied as a function of various molar mixing ratios at different temperatures. The focus of the investigation is dynamic properties (viscosity, electrical conductivity and thermal conductivity) as well as microscopic features from theoretical studies. The effect of water is analyzed considering the large hydrophilicity of this fluid and as an approach for tailoring its physicochemical properties, which in pure state are not favorable for industrial applications. The reported results reveal a complete description of fluid’s characteristics and show how hydrogen bond donor and hydrogen bond acceptor clusters are diluted in water with increasing water absorption while hydrogen bonding is maintained upon dilution.

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The nanoscopic level properties of a mixed deep eutectic solvent composed by choline chloride as hydrogen bond acceptor and urea plus ethylenglycol plus glycerol as hydrogen bond donor are studied using classical molecular dynamics simulations. The results of the behaviour of mixed deep eutectic on 2D surfaces show strong adsorption when graphene and boron nitride are considered and minor layering for MoS2, but adsorbed layers on these materials are also heterogeneous. Likewise, the behaviour of carbon nanotubes is also analysed, confirmed preferential confinement of one of the considered hydrogen bond donors (ethylene glycol) and nanotube solvation characterized by large adsorption of the considered hydrogen bon acceptor. The reported results show heterogeneities at the nanoscopic level in the mixed deep eutectic induced by the developed preferential hydrogen bonding, which are proposed as a way to control deep eutectic solvents properties through composition.

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The properties of boron nitride-based nanomaterials that are studied on the purpose of acid gas capture were studied by a theoretically approach via both quantum chemistry and classical molecular dynamics methods. Three gases, CO2, H2S and SO2, were studied and they were considered in contact with 1D (nanotubes), 2D (nanosheets) and 3D (fulburenes) boron nitride-based nanomaterials. The reported results confirm the suitability of these nanomaterials for the adsorption of acid gases and provide molecular-level basis for the understanding of the surface properties regarding acid capturing purposes. You can access the paper from this link.