Solute Solvent Research Articles

Structured solvent on a split electron tail: A semiclassical theory of electrified metal-solution interfaces

We develop a comprehensive semiclassical continuum theory of electronic response and structured solvents at electrified metal-solution interfaces. The approach combines an orbital-free density-functional theory of electrons on the metal side with a statistical field theory of a structured electrolyte solution within a grand canonical framework. The resulting grand potential of the entire electrical double layer (EDL) is a hybrid functional of particle density, including metal electrons and classical solution particles, electric potential, and solvent polarization, referred to as density-potential-polarization functional theory (DPPFT). The DPPFT captures major atomistic phenomena within the EDL, including electron spillover, spatially damped oscillations in solvent polarization and electric potential extending toward the bulk solution, and the layered structure of ions. Based on DPPFT, an EDL model for the Ag(110)-KPF6 aqueous solution interface is parameterized using experimental data for the double-layer capacitance (). The calibrated model is employed to study the influence of electronic, ion, and solvent properties on EDL structure. profiles at different crystal faces and in various electrolyte solutions are rationalized by the model coherently. We reveal that intensified ion layering enhances the capacitance at the potential of zero charge and narrowed ionic peaks in the profile. Contrary to classical models, the DPPFT allows coions to have appreciable densities near the metal surface, with their magnitudes depending on the local solvent structure and the correlation strength between ions and solvent. All in all, the presented framework provides a holistic and computationally efficient approach for atomistic-level modeling of EDLs under constant-potential conditions. Published by the American Physical Society 2025

Accurate Determination of Molecular Sizes of a Solute in Water From its Translational Self‐Diffusion Coefficient

AbstractDetermining accurate molecular dimensions in water, from measured translational self‐diffusion coefficients (Dt), is extremely important in biochemistry, supramolecular chemistry, organometallic chemistry and beyond, but it still represents a big challenge especially for small and medium‐sized molecules. Indeed, current semiempirical adaptations of the Stokes‐Einstein equation, which allow accurate determination of molecular size of solutes in organic solvents, proved inadequate for aqueous systems. To overcome such a major limitation, herein, we introduce a novel approach that unlocks the quantitative interpretation of Dt in water. By analyzing ~70 diverse molecules with volumes ranging from 101 Å3 to 103 Å3, and selecting the partial molar radius (rM) as a reliable proxy for the hydrodynamic radius (rH), we derived a semiempirical equation that enables accurate determination of hydrodynamic volume (VH) of solutes in aqueous solutions, effectively accounting for the distinctive hydrogen‐bonding properties of water. This approach fills a crucial gap, enhancing precise molecular characterization of polar and non‐polar solutes in water.

Effects of dopant solution solvent on the stability of doped P3HT films

Effects of dopant solution solvent on the stability of doped P3HT films

Solvatochromic Analysis of Triton X-100 in Binary Mixtures

Binary solvent mixtures of the non-ionic surfactant Triton X-100 with water, methanol, ethanol, and 1-propanol, respectively, were investigated by solvatochromic studies. The absorption spectral bands of methyl red dye, used as a solvatochromic probe, were recorded in ternary solutions prepared with different mole ratios between Triton X-100 and water/alcohols. The Kamlet–Abboud–Taft model was applied to estimate the contribution of each type of intermolecular interaction to the total shift of the electronic absorption band of the solute. The composition of the solute molecule’s first solvation shell was comparatively estimated by using three models: the statistical cell model of ternary solutions, the Suppan model, and the Bosch–Rosés model. The statistical cell model allows the estimation of the difference between the interaction energies in the solute–solvent pairs of molecules. The Bosch–Rosés model provided important information on the 1:1 complex formed between Triton X-100 and water/alcohol molecules, as well as on the symmetry/asymmetry related to the binary mixtures in the cybotactic region of the solute’s molecule.

How Microsolvation Affects the Balance of Atomic Level Mechanism in Substitution and Elimination Reactions: Insights into the Role of Solvent Molecules in Inducing Mechanistic Transitions

Solvents play a crucial role in ion–molecule reactions and have been used to control the outcome effectively. However, little is known about how solvent molecules affect atomic-level mechanisms. Therefore, we executed direct dynamics simulations of the HO−(H2Ow) + CH3CH2Br system to elucidate the dynamics behavior of chemical reactions in a microsolvated environment and compared them with previous gas-phase data. Our results show that the presence of a single water solvent molecule significantly suppresses the direct mechanism, reducing its ratio from 0.62 to 0.18, thereby promoting the indirect mechanism. Spatial effects and prolonged ion–molecule collisions combine to drive this mechanism shift. Among them, water molecules impede the reactive collisions of HO− and CH3CH2Br, while at the same time, the attractive interaction of hydrogen bonds between ions and molecules produces long-lived intermediates that favor the indirect mechanism. On the other hand, microsolvation also affects the reaction preference of the SN2 and E2 channels, which is more conducive to stabilizing the transition state of the SN2 channel due to the difference in solute–solvent interactions, thus increasing the competitiveness of this pathway. These results emphasize the profound influence of solvent molecules in regulating reaction selectivity and underlying microscopic mechanisms in more complex systems.

Synthesis, structure and fluorescence of a novel zinc(II) polymer based on N-[(3-pyridine)-3-sulfonyl]-threonine

Abstract A novel zinc(II) polymer based on pyridine sulfonyl amino acid, namely [Zn(HL)(H2O)2]n·4H2O (1) (HL=(1-carboxylato-2-hydroxypropyl)(pyridin-3-sulfonyl)-threonine), was synthesized by reacting Zn(NO3)2·6H2O with H3L in a mixed solvent solution of MeCN/EtOH/H2O under acidic conditions. Single crystal X-ray diffraction analysis revealed that the polymer 1 crystallized in trigonal crystal system, space group P3121. Notably, the unit cell of the as-formed polymer 1 contains only one crystallographically independent zinc(II) ion, and the divalent anion ligand HL adopts a coordination pattern of η 1 :η 2 :μ 2. The zinc(II) central ions are connected by bridging coordination with the HL ligand through pyridyl nitrogen and carboxy oxygen atoms to form an infinite helix chain. Furthermore, numerous hydrogen bonds were observed among these chains, joining them into a 2D supramolecular network. Finally, the complex is stacked along the 31 helical axis to yield a three-dimensional supramolecular structure. Additionally, the thermal stability and photoluminescence properties of 1 were determined and discussed.

On-Chip Stimulated Raman Scattering Imaging and Quantification of Molecular Diffusion in Aqueous Microfluidics.

Numerous chemical reactions and most life processes occur in aqueous solutions, where the physical diffusion of small molecules plays a vital role, including solvent water molecules, solute biomolecules, and ions. Conventional methods of measuring diffusion coefficients are often limited by technical complexity, large sample consumption, or significant time cost. Here, we present an optical imaging method to study molecular diffusion by combining stimulated Raman scattering (SRS) microscopy with microfluidics: a "Y"-shaped microfluidic channel forming two laminar flows with a stable concentration gradient across the interface. SRS imaging of a specific molecule allows us to obtain a high-resolution chemical profile of the diffusion region at varying inspection locations and flow rates, which enables the extraction of diffusion coefficients using the convection-diffusion model. As a proof of concept, we measured diffusion coefficients of molecules including water, protein, and multiple ions, with a sample volume of less than 1 mL and a time cost of less than 10 min. Moreover, we demonstrated a high-resolution three-dimensional (3D) reconstruction of the diffusion patterns in the microfluidic channel. The high-speed microfluidic SRS platform holds the potential for quantitative measurements of molecular diffusion, chemical reaction, and fluidic dynamics at the liquid-liquid interfaces.

Study of physiochemical properties of trisubstituted pyrazole derivatives using polar aprotic solvents

Pyrazole derivatives are aromatic heterocyclic compounds endowed with multifaceted applications. In the present study 1,3,4-trisubstituted pyrazoles derivatives have been synthesized for the purpose of studying their physical properties and their characterization was done by FTIR, 1H NMR and 13C NMR spectroscopic technique. The measurement of densities (ρ) and viscosities (η) of solutions of substituted pyrazole derivative in polar aprotic solvent i.e., Dimethyl sulfoxide (DMSO), nitromethane (NM) as well as in their 1:1 binary mixture (DMSO + NM) was done at 310 K over a wide range of solute concentration (5–100) × 10–4 mol dm−3. The experimental results were used to determine the excess molar volumes (VmE). The data of density–viscosity revealed the dipole–dipole interactions occurred between the pyrazole derivative (solute) and the solvent (DMSO, NM). Excess molar studies (VmE) revealed that solute–solvent interaction was found to be stronger in case of nitromethane solvent.

Selective Hydrogen Isotope Exchange Catalysed by Simple Alkali‐Metal Bases in DMSO

Isotope Exchange processes are becoming the preferred way to prepare isotopically labelled molecules, avoiding the redesign of multistep synthetic protocols. In the case of deuterium incorporation, the most used strategy has employed transition metals, that offer high reactivity under mild reaction conditions. Despite their success, the trade‐off is that these metals are precious, and often exhibit high toxicity. Therefore, alternative protocols using earth abundant catalysts would be a welcome addition to this field. Here, we show how the simple bases NaHMDS (HMDS = hexamethyldisilazide) and NaCH2SiMe3 can efficiently and selectively promote deuteration of a wide range of C(sp2)–H and C(sp3)–H bonds in DMSO‐d6, providing an easy and direct access to deuterated compounds. Heterocycles, fluoroarenes, N‐heterocyclic carbenes, amides and other aromatic molecules could be deuterated under mild conditions using catalytic amounts of base. Mechanistic studies have flagged up the importance of the metalated substrate and metalated solvent in solution, establishing an equilibrium between these compounds, which is crucial for the success of this approach. An alkali‐metal effect was observed, with heavier alkali‐metal amides being more reactive at room temperature, but their lower stability at higher temperatures made sodium bases the optimal reagents for Hydrogen Isotope Exchange.

Selective Hydrogen Isotope Exchange Catalysed by Simple Alkali-Metal Bases in DMSO.

Isotope Exchange processes are becoming the preferred way toprepare isotopically labelled molecules, avoiding the redesign of multistep synthetic protocols. In the case of deuterium incorporation, the most used strategy has employed transition metals, that offer high reactivity under mild reaction conditions. Despite their success, the trade-off is that these metals are precious, and often exhibit high toxicity. Therefore, alternative protocols using earth abundant catalysts would be a welcome addition to this field. Here, we show how the simple bases NaHMDS (HMDS = hexamethyldisilazide) and NaCH2SiMe3can efficiently and selectively promote deuteration of a wide range of C(sp2)-H and C(sp3)-H bonds in DMSO-d6, providing an easy and direct access to deuterated compounds. Heterocycles, fluoroarenes,N-heterocyclic carbenes, amides and other aromatic molecules could be deuterated under mild conditions using catalytic amounts of base. Mechanistic studies have flagged up the importance of the metalated substrate and metalated solvent in solution, establishing an equilibrium between these compounds, which is crucial for the success of this approach. An alkali-metal effect was observed, with heavier alkali-metal amides being more reactive at room temperature, but their lower stability at higher temperatures made sodium bases the optimal reagents for Hydrogen Isotope Exchange.

The Adducts Lipid Peroxidation Products with 2′-DeoxyNucleosides: A Theoretical Approach of Ionisation Potential

The human body contains ~1014 cells—each of which is separated by a lipid bilayer, along with its organeller. Unsaturated fatty acids are located on the external layer and, as a result, are particularly exposed to harmful factors, including xenobiotics and ionising radiation. During this activity, lipid peroxidation products are generated, e.g., 4-hydroxy-2-nonenal (HNA), 4-oxo-2(E)-nonenal (ONE), and malondialdehyde (MDA). The mentioned aldehydes can react with cytosolic 2′-deoxynucleosides via Michael addition. In this paper, the following adducts have been taken into theoretical consideration: ε-dCyt, H-ε-dAde, ε-dCyt, H-ε-dAde, H-ε-dGua, R/S-OH-PdGua, N2,3-ε-dGua, M1-dGua, N1-ε-dGua, and HNE-dGua. The presence of the above molecules can alter a cell’s antioxidant pool. With this in mind, the adiabatic ionisation potential (AIP) and vertical ionisation potential (VIP), as well as the spin and charge distributions, are discussed. For this purpose, DFT studies were performed at the M06-2x/6-31++G** level of theory in the aqueous phase (both non-equilibrated (NE) and equilibrated (EQ) solvent–solute interaction modes), together with a Hirshfeld charge and spin distribution analysis. The obtained results indicate that the AIPs of all the investigated molecules fell within a range of 5.72 and 5.98 eV, which is consistent with the reference value of 7,8-dihydro-8-oxo-2′-deoxyguanosine (OXOdGua), 5.78 eV. N2,3-ε-dGua and M1-dGua were the only exceptions, whose VIP and AIP were noted as higher. The electronic properties analysis of 2′-deoxynucleoside adducts with lipid peroxidation products reveals their potential influence on the cells’ antioxidant pool, whereby they can affect the communication process between proteins, lipids, and nucleotides.

Solvent solutions: comparing extraction methods for edible oils and proteins in a changing regulatory landscape. General introduction

Hexane is currently the dominant solvent in the oil extraction industry, valued for its efficiency, low cost, and ability to preserve the quality of oils and proteins. However, this solvent poses health and environmental risks due to its toxicity. Recently, EFSA recommended a reevaluation of hexane as a processing aid due to gaps in toxicity studies and population exposure data. Consequently, a reduction in tolerated residue limits or usage restrictions can be anticipated, potentially leading industrialists to consider alternative solutions. The series of articles introduced here aims to examine the potential consequences of replacing hexane with alternative solvents listed in Directive 2009/32/EC. This comprehensive dossier, comprising eight articles, thoroughly investigates various critical aspects of oilseed extraction. The series explores physicochemical properties (Part 1), safety considerations (Part 2), processing impacts (Part 3), energy consumption (Part 4), oil quality (Part 5), protein meal quality (Part 6), technological comparisons (Part 7), and alternative extraction technologies (Part 8). This in-depth exploration provides a holistic analysis of the challenges and opportunities associated with transitioning from hexane to alternative solvents in the oilseed extraction industry.

A Greener Solution to Direct Low-Temperature Incorporation of Selenium in Chalcogenide Solar Absorber

Low temperature environment friendly solution processing of metal chalcogenide absorbers is highly desired for low-cost and scalable fabrication of thin-film solar cells. However, the incorporation of selenium (Se) into sulfo-selenide absorber films previously reported devices has required the use of harmful solvents in the precursor solution and/or a high-temperature selenization compatible with the substrate type configuration. In this study, we address these issues by introducing a novel, less toxic thiol-amine-based solvent system designed for the direct incorporation of Se. This approach enables the synthesis of sulfo-selenide absorbers at significantly lower temperatures as demonstrated by the successful fabrication of a selenization free CZTSSe absorber layer within a superstrate-type thin-film solar cell for the first time. Our method not only reduces the environmental footprint of the fabrication process but also has the potential for offering the scalability and cost-effectiveness in producing chalcogenide thin films for energy device applications.

Thermodynamic and spectroscopic study of solutions of therapeutic deep eutectic solvents (THEDES) in supercritical CO2

Thermodynamic and spectroscopic study of solutions of therapeutic deep eutectic solvents (THEDES) in supercritical CO2

Self-limiting selective phase separation of graphene oxide and polymer composite solution.

Homogeneous mixtures undergo phase separation to generate rich heterogeneous structures as well as enable complex physiological activity and delicate design of artificial materials. Beyond free space, the strong coupling between migrating components and spatial confinement plays a crucial role in determining the essential spatial compartment of phase separation, warranting further continuous exploration. Herein, we report the selective phase separation (SPS) behavior of polymers under a mobile two-dimensional (2D) confinement by graphene oxide (GO) sheets. The selection of a poor solvent triggers the occurrence of SPS in a homogeneous solution of GO and polymers. We reveal that the self-limiting spatial confinement of GO sheets leads to the migration of polymers to form independent and continuous phase in 2D confinement. We examine the quantitative rule of size and continuity of polymer phases in correlation with solvent properties and solute constitutes. The observed SPS allows the facile generation of heterogenous nanostructures in GO/polymer composites. We initiate a SPS wet-spinning to fabricate radial heterogenous fibrous graphene composite fibers with ultrahigh elongation at break and superior flexibility. The observed SPS can inspire more exceptional phase separation behaviors under mobile 2D confinement and offers a facile method to delicately design 2D heterogeneous nanostructured materials.

Rat Fecal Metabolomics-Based Analysis.

The gut's symbiome, a hidden metabolic organ, has gained scientific interest for its crucial role in human health. Acting as a biochemical factory, the gut microbiome produces numerous small molecules that significantly impact host metabolism. Metabolic profiling facilitates the exploration of its influence on human health and disease through the symbiotic relationship. Fecal metabolomics-based analysis is an indisputably valuable tool for elucidating the biochemistry of digestion and absorption in the gastrointestinal system, serving as the most suitable specimen to study the symbiotic relationship between the host and the intestinal microbiota. It is well-established that the balance of the intestinal microbiota changes in response to various stimuli, both physiological, such as gender, age, diet, and exercise, and pathological, such as gastrointestinal and hepatic diseases. Fecal samples have been analyzed using widely adopted analytical techniques, including NMR spectroscopy, GC-MS, and LC-MS/MS. Rat fecal samples are frequently used and particularly useful substrates for metabolomics-based studies in related fields.The complexity and diversity of fecal samples necessitate careful and skillful handling to extract metabolites, while avoiding their deterioration, effectively and quantitatively. Several determinative factors, such as the fecal sample weight to extraction solvent solution volume, the nature and pH value of the extraction solvent, and the homogenization process, play crucial roles in achieving optimal extraction for obtaining high-quality metabolic fingerprints, whether for untargeted or targeted metabolomics.

Aprotic Electrolytes Beyond Organic Carbonates: Transport Properties of LiTFSI Solutions in S-Based Solvents.

This work illustrates a physico-chemical study of the structural, dynamic, and transport properties of electrolytes made of LiTFSI solutions in sulphoxide and sulphone solvent mixtures. Experimental measurements, by Raman and NMR spectroscopies, as well as electrochemical impedance spectroscopy, reveal the formation of a variety of ionic aggregates depending on the solvent composition that significantly affect the ion mobility and conductivity of the electrolyte. Mixtures containing tetrahydrothiophene-1-oxide exhibit a larger ion mobility due to a rapid exchange mechanism between solvent molecules, whereas the use of tetramethylene sulphone favors the formation of ionic aggregates due to the strong dipolar interactions between solvent molecules.

A coarse‐graining approach to model molecular liquids for mesoscale problems

AbstractEffective modeling of molecular interactions is fundamental for understanding and simulating large‐scale chemical and biochemical systems. Here, we introduce a novel coarse‐graining strategy that employs the Lennard–Jones (LJ) potential to model solvent–solvent and solute–solvent interactions that control mesoscale behaviors. Our approach maintains the accuracy in capturing essential thermophysical properties such as densities and vapor pressures, while simplifying the representation of solvent molecules. By aggregating multiple solvent molecules into a single bead, our model offers a robust tool for studying solvation properties in systems where the collective behavior of solvents plays a crucial role. This approach enables effective computational studies across various mesoscale phenomena, including phase transitions in polymer blends, concentrated solutions of small organic molecules, and biological self‐assembly. We demonstrate the robustness of our approach by simulating a saturated cholesterol–ethanol solution, exemplifying its power to tackle large‐scale systems with precision and efficiency.

Stretchable Thermochromic Fluorescent Fibers Based on Self-Crystallinity Phase Change for Smart Wearable Displays.

Smart fibers with tunable luminescence properties, as a new form of visual output, present the potential to revolutionize personal living habits in the future and are receiving more and more attention. However, a huge challenge of smart fibers as wearable materials is their stretching capability for seamless integration with the human body. Herein, stretchable thermochromic fluorescent fibers are prepared based on self-crystallinity phase change, using elastic polyurethane (PU) as the fiber matrix, to meet the dynamic requirements of the human body. The switching fluorescence-emitting characteristic of the fibers is derived from the reversible conversion of the dispersion/aggregation state of the fluorophore coumarin 6 (C6) and the quencher methylene blue (MB) in the phase-change material hexadecanoic acid (HcA) during heating/cooling processes. Considering the important role of phase-change materials, thermochromic fluorescent dye is encapsuled in the solid state via the piercing-solidifying method to avoid the dissolution of HcA by the organic solvent of the PU spinning solution and maintain excellent thermochromic behavior in the fibers. The fibers obtained by wet spinning exhibit good fluorescent emission contrast and reversibility, as well as high elasticity of 800% elongation. This work presents a strategy for constructing stretchable smart luminescence fibers for human-machine interaction and communications.

Martignac: Computational Workflows for Reproducible, Traceable, and Composable Coarse-Grained Martini Simulations.

Despite their wide use and far-reaching implications, molecular dynamics (MD) simulations suffer from a lack of both traceability and reproducibility. We introduce Martignac: computational workflows for the coarse-grained (CG) Martini force field. Martignac describes Martini CG MD simulations as an acyclic directed graph, providing the entire history of a simulation─from system preparation to property calculations. Martignac connects to NOMAD, such that all simulation data generated are automatically normalized and stored according to the FAIR principles. We present several prototypical Martini workflows, including system generation of simple liquids and bilayers, as well as free-energy calculations for solute solvation in homogeneous liquids and drug permeation in lipid bilayers. By connecting to the NOMAD database to automatically pull existing simulations and push any new simulation generated, Martignac contributes to improving the sustainability and reproducibility of molecular simulations.