Solvent Effects Research Articles

Newfound 2D In2S3 allotropy monolayers for efficient photocatalytic overall water splitting to produce hydrogen

Allotropy structures may induce different electronic and optical properties, which implies that one can acquire novel performance by screening its allotropy structures. Here, we demonstrate that two In2S3 allotropy monolayers with excellent photocatalytic performance for water splitting to produce hydrogen are screened from 1038 In2S3 allotropy monolayers. The phonon dispersions are calculated for 39 allotropes with the lowest formation energies, which confirms that 16 allotropes have dynamic stability, including the only one reported in the literature. The results of overpotentials of band edges demonstrate that 8 allotropes match the potential requirements of overall water splitting. The thermodynamic stability of these allotropes is further confirmed for the obtained allotropes. Then, two allotropes with maximum solar-to-hydrogen efficiency of 17.78% and 29.32% are screened. The Gibbs free energy with the solvent effect indicates that one allotrope can proceed photocatalytic hydrogen/oxygen evolution reactions spontaneously. Therefore, the newfound In2S3 allotropy monolayers have potential applications in photocatalytic overall water splitting for hydrogen generation.

Cu-trimesate and mesoporous silica composite as adsorbent showing enhanced CO2/CH4 and CO2/N2 selectivity for biogas and flue gas separation

Due to their diverse structure, high porosity, and tunable functionality, Metal-Organic Frameworks (MOFs) hold great potential as materials for diverse applications, including gas separation. Material science researchers are focusing on creating flexible materials that have special properties. Most of the latest research mainly concentrates on fabricating composite materials of MOFs and other functional materials. These MOF-based composites can mitigate the limitations of pure MOFs and may even perform better than the individual components. Here, we present a systematic study on the effect of solvent in synthesising a composite (Cu-BTC@SBA-15) of Cu-trimesate MOF (aka CuBTC) and ordered mesoporous silica SBA-15, showing considerable improvement in selectivity for CO2 adsorption from the flue gas and biogas. The pristine Cu-BTC, SBA-15 and the composites with different content of Cu-BTC were characterized by PXRD, BET, FT-IR, SEM, TEM and TGA techniques. The pure gas adsorption isotherms were measured for CO2, CH4, and N2 gases. Ideal Adsorbed Solution Theory (IAST) is used for the binary selectivity calculations for gas systems such as CO2/CH4 and CO2/N2 in the context of biogas and flue gas separation. The composite exhibited an increase in CO2/CH4 selectivity by 39 % compared to pure Cu-BTC and 85 % compared to pure SBA-15. For the CO2/N2 system, the composite showed 38 % higher selectivity than Cu-BTC. The work has significance in the design of effective MOF-based composites for CO2 separation. Our work might open up a new route to design multifunctional materials for worldwide applications through an adsorptive and or mixed matrix membrane route.

A Novel Rhodamine B Derivative as a "Turn-on" Fluorescent Sensor for Cu2+ with High Selectivity and Sensitivity.

The number of "turn-on" fluorescent probes for Cu2+ is relatively limited, and interference from other metal cations presents a significant challenge for these sensors. In this study, we synthesized and characterized a rhodamine B-based sensor, designated as RBHP, using 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) and rhodamine B hydrazide. Selectivity, sensitivity, solvent effects, water content, and pH of RBHP in relation to Cu²⁺ were conducted. RBHP exhibited an exceptionally low fluorescence background signal in acetonitrile and demonstrated a "turn-on" fluorescent response to Cu²⁺. The PMBP-based acylhydrazone moiety and acetonitrile as the detection solvent are crucial for the selective detection. RBHP shows potential as a highly selective and sensitive fluorescent sensor for Cu2+.

Effects of Solvation and Temperature on the Energetics of BiVO4 Surfaces with Varying Composition for Solar Water Splitting

Effects of Solvation and Temperature on the Energetics of BiVO₄ Surfaces with Varying Composition for Solar Water Splitting

Effect of solvent and temperature on the micellization and thermophysical properties of cetyltrimethylammonium bromide

The Micellization is the fundamental phenomenon in colloid and surface chemistry which plays a pivotal role in a multitude of industrial processes, biological systems, and everyday applications. In this study, we investigate the micellization behavior of the cationic surfactant, cetyltrimethylammonium bromide (CTAB) within aqueous and ethanol–water mixtures across a temperature range. The electrical conductivity measurements unveil insights into the critical micelle concentration (CMC) and the degree of counterion dissociation (β) at each temperature. Notably, as ethanol content increases in the solvent, both CMC and β values exhibit a corresponding uptick. These findings enable the assessment of standard Gibbs free energy (ΔGmic0). Furthermore, our investigation extends to find out the thermophysical properties (viz., density, dynamic viscosity, and kinematic viscosity) assessments across varying ethanol compositions and temperatures. These metrics facilitate the calculation of activation energy for mixed systems. The implications of these results (data) could be useful for both the fundamental as well applied research, and promise valuable insights for future endeavors.

Exploring the adsorption characteristics of quinoline derivatives on iron via ab initio DFT simulations and COSMO-RS profiles

Quinoline derivatives have been the subject of extensive research due to their excellent electronic properties and wide range of applications. This study conducts a comprehensive computational examination of the adsorption properties of substituted quinoline derivatives on Fe(110) surfaces. Four specific compounds, namely 2-amino-7-hydroxy-4-phenyl-1,4-dihydroquinoline-3-carbonitrile (QN1), 2-amino-7-hydroxy-4-(p-tolyl)-1,4-dihydroquinoline-3-carbonitrile (QN2), 2-amino-7-hydroxy-4-(4-methoxyphenyl)-1,4-dihydroquinoline-3-carbonitrile (QN3), and 2-amino-4-(4-(dimethylamino)phenyl)-7-hydroxy-1,4-dihydroquinoline-3-carbonitrile (QN4) were investigated using first-principles density functional theory (DFT) calculations along with COSMO-RS analysis for solvation properties. Our results revealed that the presence of functional groups significantly influence the adsorption strength on Fe(110) surfaces. Quinoline molecules have adsorbed on the iron surface through complex mechanisms involving physical interactions and charge transfer. Specifically, QN1 and QN4 showed strong physical interactions with iron atoms while QN2 and QN3 exhibited high affinity to coordinate with Fe atoms. The stability of coordinated quinolines was enhanced by a notable charge redistribution and bond formation as observed via projected density of states (PDOS). On the other hand, electron density difference (EDD) and electron localization function (ELF) iso-surfaces highlighted the critical role of van der Waals interactions, predominantly influenced by nitrogen atoms, in stabilizing the adsorbed molecules. The COSMO-RS analysis elucidated the solvation characteristics, emphasizing the importance of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) in the interaction of quinolines with water molecules. Overall, this study provides crucial insights into the molecular mechanisms underlying the corrosion inhibition properties of quinoline derivatives, emphasizing the influence of functional groups and solvation effects on adsorption behavior and stability.

Effect of conformational landscape on the polymorphism and monomorphism of tizanidine cocrystallization outcomes

Molecular conformational diversity plays a crucial role in both polymorphic nucleation and cocrystal formation during the cocrystallization process. However, the relationship between molecular conformation and cocrystallization polymorphism is not well-explored. Herein, the impact of molecular conformational landscapes on cocrystallization outcomes was investigated using tizanidine (TZND) as model compound. Four coformers, namely maleic acid (MA), salicylic acid (SA), p-hydroxybenzoic acid (pHBA), and heptanedioic acid (HDA), were employed and five salt forms were developed for the first time. Compared with TZND, all five salts showed significantly improved water solubility and dissolution rate. The cocrystallization behavior of TZND varied with each coformer: MA exhibited solvent-dependent polymorphism, while SA, pHBA, and HDA showed solvent-independent monomorphism. Crystal structure and conformational analyses revealed the conformational variation of TZND across different cocrystallization outcomes. Molecular dynamics simulations and quantum chemical calculations demonstrated that the interplay between solvent effects and coformer interactions determines the dominant conformations of TZND. The cocrystallization nucleation process was also examined, and the molecular mechanism that explains both polymorphism and monomorphism in the cocrystallization of TZND was proposed.

Alkali‐Mediated/Catalyzed Transition‐Metal‐Free Tandem Reaction Triggered by the Borrowing Hydrogen and Aerobic Dehydrogenation Processes of Alcohols

AbstractThe transformation of alcohols to important classes of compounds is a central topic in chemistry because they are abundant, renewable, and attractive building blocks. The alkali‐mediated/catalyzed borrowing hydrogen and aerobic dehydrogenation processes of alcohols open a new and sustainable access for the alcohol conversion under transition‐metal‐free conditions. In this review, we summarize the recent alkali‐mediated/catalyzed sequential reactions involving the borrowing hydrogen and aerobic dehydrogenation processes of alcohols. Furthermore, this review not only introduces the tentative pathways of these transformations, but also discusses the role of alkali, solvent effects, and substrate reactivity on these reactions.

Modeling conformational changes in alginic acid oligomers induced by external forces

In this study, the mechanism and nature of mechanical force-induced conformational transitions of alginate oligomers with different ratios of β-D-mannuronic acid (M unit) and α-L-guluronic acid (G unit) units were investigated. The influence of the type of glycosidic linkage in either homo- or heterooligomers on the nature of conformational transitions was also considered. For this purpose, two different theoretical methods were used: quantum mechanics (QM) at the DFT level with the EGO (Enforced Geometry Optimization) approach previously tested also for other saccharide systems, and molecular dynamics (MD) simulations within hybrid interaction potentials, which take into account both the ab initio (QM) level of theory and classical molecular mechanics (MM) force fields. This allowed to characterize in detail the structural and energetic properties of the conformational transition occurring upon the influence of external, mechanical forces (e.g. ring conformations at the path of ring-inversion process as well as the energies corresponding to initial, final and intermediate states). The results indicate qualitatively various responses against the applied force, depending on the G:M ratio, which have their source in differing topologies of glycosidic linkage in either G or M units. This is of potential relevance for determining the content of naturally heterogeneous alginate chains by the AFM experimental studies. The effects of explicit solvent and non-zero temperature are not of primarily importance in the context of determined stretching properties.

Effect of high-boiling point solvents on inkjet printing of catalyst layers for proton exchange membrane fuel cells

Inkjet printing (IJP) is considered as a promising and flexible method for low cost and drop-on-demand pattern formation in proton exchange membrane (PEM) fuel cells. Although significant advancements have been made in inkjet-printed electrodes, identifying the optimal ink formulations remains challenging due to severe restrictions on the ink properties. Generally, the catalyst layer prepared by IJP using low boiling point solvents (water/alcohol) show reasonable electrochemical performance. However, low boiling point solvents lead to clogging of the printhead nozzle due to fast evaporation of the solvent in the inkjet print head. In this study, high boiling point solvents (propylene glycol (PG) or ethylene glycol (EG)) were used as additives to reduce nozzle clogging and improve printing efficiency. In this context, the relationship between catalyst ink properties, CL microstructure, and electrochemical performance of the MEA is investigated. Results show that printing time is significantly reduced with adding high boiling point solvents in the ink (66.67 % reduction of time with 30 wt% PG). However, an increased amount of additive is detrimental in terms of electrochemical performance due to formation of larger agglomerates, lower porosity of the catalyst layer, and reduced ECSA. The results of this work can be used to develop a strategy to adjust the trade-off between printing time and electrochemical performance of electrodes prepared using IJP.

Innovative preparation of polyimide/polysulfone amide (PI/PSA) membrane-pore-like nanofibers with biomimetic penguin feather shaft structure and thermal insulation performances

The white-browed penguin can survive in extreme environments due to its unique feather structure. The feather shafts of penguins are porous, separated by the membrane-pore-like structure made of keratin fiber membranes. The feather branches are densely arranged around the feather shafts. This unique structure provides inspiration for researchers. In this work, we developed a simple method to construct polyimide/polysulfone amide (PI/PSA) membrane-pore-like structure nanofibers resembling penguin feather shafts and studied the effects of different low-boiling point solvents (tetrahydrofuran (THF), ethyl acetate (EA), and acetone (AC)) on the morphology, tensile properties, and thermal insulation properties of PI/PSA membrane-pore-like structure nanofibers. Comprehensive characterization was also performed using scanning electron microscope, total reflection infrared spectrometer, X-ray diffractometer, universal testing machine, thermal conductivity meter, pore size analyzer, thermal gravimetric analyzer, infrared thermal imaging instruments, and thermocouple testing instruments. The results showed that when the mass ratio of THF to N, N-dimethylacetamide (DMAC) was 20/80, the prepared PI/PSA membrane-pore-like structure nanofibers exhibited excellent thermal insulation properties, with a low thermal conductivity of 0.0436 W·m−1·K−1, a breaking strength of 7.72 ± 2.64 MPa, and a breaking elongation of 8.19 ± 4.07 %. The biomimetic membrane-pore-like structure with excellent thermal insulation properties is expected to be applied in various fields, such as heat-protective clothing and architectural coatings in harsh environments.

Mitigating anodic corrosion in aluminum–air batteries: Effects of alkali metal cation size on electrochemical performance

Anodic corrosion limits the performance of aluminum–air batteries (AABs) by reducing discharge capacity and hindering energy density. This study proposes a strategy to mitigate anodic corrosion by controlling electrolyte cations to decrease the activity of free water molecules in the anodic corrosion process. Alkali metal cations (Na+, K+, Rb+) are introduced into a 1mol dm−3 KOH solution to examine their solvation properties and effects on free water molecule activity. Results show that larger cations (Na+ < K+ < Rb+) enhance anode discharge capacity by promoting more stable discharge reactions. Raman spectroscopy reveals that as cation radius increases, free water molecule activity decreases due to increased hydration. X-ray photoelectron spectroscopy analysis shows that larger cations favor the formation of corrosion-resistant aluminum compounds like Al2O3 and Al(OH)3, due to their higher concentration in the electric double layer, inhibiting anodic corrosion. This study highlights the critical role of cation solvation in enhancing electrochemical performance and corrosion resistance of AAB anodes.

Impact of solvent and water activity on lipase selectivity and acyl migration of ARA-rich 2-monoacylglycerols in catalytic systems: Kinetic study by particle swarm optimization

The 2-arachidonoylglycerol enzymatic alcoholysis reaction model was established and kinetic parameters were calculated to explore the effects of solvent and water activity (aw) on the lipase positional selectivity and 2-monoacylglycerol acyl migration. Six rate constants (k1-k6) with the lowest mean square error were obtained using the particle swarm optimization algorithm, and the calculated molar concentration-time curves were well-fitted to the actual curves. As an indicator to characterize the positional selectivity of lipase, k5/k3 was significantly associated with log P of solvent, which first increased and then decreased with the increase of aw. The highest sn-1,3 selectivity of Lipozyme TL IM was found at the aw of 0.53. The changes of acyl migration with the solvent and aw in the enzymatic and non-catalytic systems showed a consistent law. This study provides theoretical support for the targeted synthesis of structural lipids and enzymatic production of diverse structural lipid products.

Quantifying mass-dependent isotope fractionation and nuclear field shift effects for the light rare Earth elements in hydrous systems

The improving sensitivity of mass-spectrometers has opened the potential of using stable isotope signatures of the rare Earth elements (REE) as geochemical tracers. However, thus far only limited studies have utilised REE stable isotopes, despite resolvable variations having been observed in a range of systems. An interesting but poorly explored area remains variations in aqueous environments across a range of temperatures including seawater, marine sediments, ion adsorption deposits or hydrothermal systems. Furthermore, the magnitudes and competing effects of mass-dependent isotope fractionation and mass-independent nuclear field shift effects, which can be significant factor for heavy elements especially at high temperatures, remain poorly understood.To contribute to a holistic understanding of REE isotope signatures, we calculated reduced partition function ratios (as 103lnβ) for mass-dependent and nuclear field shift effects for aqueous La, Ce, and Nd complexes from first principles. Theoretical calculations were compared with experimental data, and this demonstrates that calculations involving a combination of two explicit hydration shells and additional implicit solvation effects are required to accurately describe the coordination and molecular vibrations of aqueous complexes. This data was then combined with speciation modelling of seawater and hydrothermal fluids to assess isotope fractionation in hydrous systems. The predicted magnitude of isotope fractionation is significant in low (T = 25 °C) temperature systems (Δ139/138LaMax-Min = 0.20 ‰, Δ142/140CeMax-Min = 0.33 ‰, Δ146/144NdMax-Min = 0.34 ‰) and remains above currently achievable analytical uncertainties even at high (T = 500 °C) temperatures (±0.015 ‰ for δ146/144Nd; ±0.040 ‰ for δ142/140Ce). Unless oxidation occurs, which is only relevant for Ce in terrestrial environments, nuclear field shift effects are negligible even at temperatures up to 500 °C. The large difference in nuclear charge radius between 140Ce and 142Ce strongly enriches the lighter Ce isotope in the higher oxidation state (103lnβCe(IV)-Ce(III) = −0.45 at 25 °C) which almost completely cancels out the opposing mass-dependent effect (103lnβCe(IV)-Ce(III) = +0.46 at 25 °C). This means that variations in δ142/140Ce isotope signatures cannot easily be related to oxidation in ancient or recent environments.

Electrochemical Screening and DFT Analysis of Acetylacetonate Metal Complexes in Organic Solvents

Seven acetylacetonate (acac) metal complexes ranging from early transition metals to post-transition metals were examined by cyclic voltammetry in acetonitrile (MeCN), dichloromethane (DCM), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), and dimethylformamide (DMF). The electronic potential of any observed redox events is reported along with an analysis of the reversibility of those events across a range of scan rates. Group 8 compounds Fe(acac)3 Ru(acac)3 showed at least quasi-reversible reductions across all solvents while Ru(acac)3 also featured a reversible oxidation. The early and post-transition compounds VO(acac)2, Ga(acac)3 and In(acac)3 exhibited irreversible reductions, while TiO(acac)2 showed no redox activity within the examined potential ranges. Mn(acac)3 featured an oxidation that showed solvent-dependent reversibility, and a reduction that was irreversible in all examined solvents. DFT calculations indicated minimal solvent effects on the HOMO-LUMO gap for the majority of compounds, but a significant effect was observed for Ru(acac)3. This study serves as a valuable initial step for further examination of acetylacetonate metal complexes for applications as electrochemical internal standards, nanoparticle precursors, and electrocatalysts.

Exploring the mechanisms of benzanilide crystal growth and morphology: Crystal surface structure, solvent diffusion and solvent-interface interactions

Flaky crystals are fragile, rendering them unsuitable for various applications including use, processing, storage and transportation. This work investigates the growth and morphology regulation mechanisms of flaky crystals using benzanilide as a model material. Initially, block-like crystals are prepared by solvent screening and cooling crystallization with its morphology greatly improved. Subsequently, growth kinetics of (111), (1–10) and (020) faces are established with crystal growth experiments. The crystal growth of (001) face is also determined to follow a two-dimensional nucleation model with the microscopic surface analysis using atomic force microscopy. The changes of the surface integration resistance and the growth step height are regarded as kinetic mechanisms of the growth behavior and crystal morphology modulation by solvent and supersaturation. Finally, the molecular mechanism of the modulation of the solvent in crystal morphology is revealed base on crystal surface structure analysis and molecular dynamics simulations. The weak solvent-interface polar interactions facilitate the incorporation of benzanilide molecules into the weak polarity (001) face, leading to the surface roughening and increased crystal thickness when employing strongly polar solvents such as acetonitrile. Unlike the former, the relatively weak hydrogen bonding interactions between solvents and strong polarity (020) face, and the higher diffusion ability of molecules promote the rapid growth and disappearance of (020) face in ethanol and acetonitrile with strong hydrogen bond formation ability. This study can contribute to a deeper understanding of the solvent effect on crystal morphology and provide guidance for optimizing crystallization conditions to obtain shape-tailored crystal products.

Viscous solvent effect on fracture of predamaged double-network gels examined by pre-notch and post-notch crack tests

Viscous solvent effect on fracture of predamaged double-network gels examined by pre-notch and post-notch crack tests

Azo Coupling Reaction for Spectrophotometric Determination of Sulfanilamide Using β -Naphthol as a Reagent

This research is based on one simple and good method for determining sulfanilamide in its pure state and in pharmaceutical preparations. Spectrophotometric determination of Sulfanilamide using the azo coupling reaction in an aqueous solution and several standard solutions were prepared. The optimal conditions were also studied. The effects of the type of acid and its volume, the influence of the base type and its volume, the effect of reagent volume (100 µg/ml), the effect of reaction time on the color stability of the product, the effect of adding sequence, the solvent effect, and the effect of temperature on the formation and stability of the colored product. The product for the Sulfanilamide drug is auburn at a wavelength of 489 nm; the method obeyed Beer's law in a range of concentrations ranging from 1–12 µg/ml; and the molar absorptivity was 28840.76 L/mol.cm. Sandal's sensitivity (0.00091 μg/cm), detection limit (0.2472 µg/ml), correlation coefficient value 0.9984, and RSD% value 0.01365, By applying the method to a pharmaceutical preparation containing Sulfanilamide, the recovery value ranged between 102.1306%.

Solvatochromism, preferential solvation and excited state dipole moments of flufenamic acid in different solvent polarities

The influence of pure solvent and binary solvent mixtures on the optical properties of non-steroidal anti-inflammatory drug (NSAID) molecule, specifically flufenamic acid (FLA), has been studied using absorption and fluorescence spectroscopic techniques. A bathochromic shift is observed in the emission wavelength of FLA with an increase in the solvent polarity of pure solvents, attributed to the highest stability of the excited state. The spectral properties are correlated with Lippert–Mataga, solvent polarity parameter, Kamlet, and Catalan solvent polarity parameters, suggesting that both general and specific solvent effects influence the spectral properties, with general solvent effects dominating over specific solvent effects. Preferential solvation studies have been carried out in tetrahydrofuran (THF) and water solvent mixture, revealing variations in the preference for solvation of FLA as a function of the mole fraction of water. Solvatochromic data are utilized to estimate the excited state dipole moment in pure solvents using different solvatochromic methods, revealing that the excited state dipole moment of FLA is higher than its ground state counterpart. The increase in dipole moment in the excited state compared to the ground state is explained based on intramolecular charge transfer (ICT), with elaboration and discussion on the possible resonance structure corresponding to ICT, inferring the more polar nature of the excited state compared to the ground state. The effect of solute polarizability on the excited state dipole moment and change in dipole moment is also discussed.

Toward Polaritonic Molecular Orbitals for Large Molecular Systems.

A comprehensive understanding of electron-photon correlation is essential for describing the reshaping of molecular orbitals in quantum electrodynamics (QED) environments. The strong coupling QED Hartree-Fock (SC-QED-HF) theory tackles these aspects by providing consistent molecular orbitals in the strong coupling regime. The previous implementation, however, has significant convergence issues that limit the applicability. In this work, we introduce two second-order algorithms that significantly reduce the computational requirements, thereby enhancing the modeling of large molecular systems in QED environments. Furthermore, the implementation will enable the development of correlated methods based on a reliable molecular orbital framework as well as multi-level methodologies able to model the inclusion of solvent effects in this kind of complex systems.