Polar Solutes Research Articles

Effects of solvents on skin absorption of nonvolatile lipophilic and polar solutes under finite dose conditions

The effects of solvents upon the deposition of a moderately lipophilic solute on skin and skin permeation were investigated previously. The present study was a continuing effort to investigate the effects of solvents on finite dose skin absorption of nonvolatile lipophilic and polar solutes and examine the relationships between solute physicochemical properties, solvent effects, and skin absorption of these solutes after solvent deposition. Skin permeation experiments under the finite dose conditions were conducted with model solutes (corticosterone, urea, mannitol, glycerol, triamcinolone acetonide, and estradiol) and model solvents (ethanol, butanol, water, and propylene glycol) using Franz diffusion cells and human epidermal membrane. Urea showed unexpectedly high skin permeation under the finite dose conditions compared to the other solutes based on their skin permeability coefficients (obtained under infinite dose condition). The influences of the solvents on solute permeation suggest that these solvents did not act solely as a vehicle for spreading the solutes during solvent deposition. In the testing of skin permeation mechanisms, model analyses indicated a correlation between solute permeation and their molecular weights and solubilities, suggesting that the solute permeation mechanism with the volatile solvent was related to solute dissolution on the skin surface and its diffusion across the skin.

The effect of compaction of a porous material confiner on detonation propagation

The fluid mechanics of the interaction between a porous material confiner and a steady propagating high explosive (HE) detonation in a two-dimensional slab geometry is investigated through analytical oblique wave polar analysis and multi-material numerical simulation. Two HE models are considered, broadly representing the properties of either a high- or low-detonation-speed HE, which permits studies of detonation propagating at speeds faster or slower than the confiner sound speed. The HE detonation is responsible for driving the compaction front in the confiner, while, in turn, the high material density generated in the confiner as a result of the compaction process can provide a strong confinement effect on the HE detonation structure. Polar solutions that describe the local flow interaction of the oblique HE detonation shock and equilibrium state behind an oblique compaction wave with rapid compaction relaxation rates are studied for varying initial solid volume fractions of the porous confiner. Multi-material numerical simulations are conducted to study the effect of detonation wave driven compaction in the porous confiner on both the detonation propagation speed and detonation driving zone structure. We perform a parametric study to establish how detonation confinement is influenced both by the initial solid volume fraction of the porous confiner and by the time scale of the dynamic compaction relaxation process relative to the detonation reaction time scale, for both the high- and low-detonation-speed HE models. The compaction relaxation time scale is found to have a significant influence on the confinement dynamics, with slower compaction relaxation time scales resulting in more strongly confined detonations and increased detonation speeds. The dynamics of detonation confinement by porous materials when the detonation is propagating either faster or slower than the confiner sound speed is found to be significantly different from that with solid material confiners.

Anti-Inflammatory and Cytotoxic Effects of Liquidambar orientalis Mill

Medicinal plants are natural sources which contain a wide range of substances. They are often used to treat various diseases due to their antimicrobial, antimutagenic and antioxidant effects. Also they are best source of many drugs. Liquidambar orientalis Mill. (L. orientalis), a medical plant is an endemic tree species in the Mediterranean region. L. orientalis also called as sweet gum, is used for such as some skin, respiratory and gastric ulser disease. We prepared some extracts that fruid, leaf and storax by use different polarity solutions. For all extracts are studied cytotoxicity assay by XTT methods in colorectal cancer cell line (HT-29, HCT-116). The most cytotoxic extract is chosen to quantitative real-time PCR (qRT-PCR) analysis. To gene expression total RNA isolated from both HT-29 and HCT-116 cell lines and NF-kB Signaling Pathway PCR Array (88 gene and 8 housekeeping gene) was studied. Leaf methanol extracts estimated IC50 values of respectively 28.30 uM, 40.42 uM in HT-29, HCT-116 cell lines after treatment with different doses of extract for 48h.According to our results some significant inflammation and immune response genes are changed (such as IL1B, TNFRSF10A). L. orientalis extract may strong potent cytotoxic and antiinflammatuar agent for colorectal cancer.

NMR Study of Solvation Effect on the Geometry of Proton-Bound Homodimers of Increasing Size.

Hydrogen bond geometries in the proton-bound homodimers of quinoline and acridine derivatives in an aprotic polar solution have been experimentally studied using 1H NMR at 120 K. The reported results show that an increase of the dielectric permittivity of the medium results in contraction of the N···N distance. The degree of contraction depends on the homodimer's size and its substituent-specific solvation features. Neither of these effects can be reproduced using conventional implicit solvent models employed in computational studies. In general, the N···N distance in the homodimers of pyridine, quinoline, and acridine derivatives decreases in the sequence gas phase > solid state > polar solvent.

Synthesis and structure of 4,6-di(tert-butyl)-2-(4-chloro-7,8-dimethylquinolin-2-yl)-7-(piperidin-1-ylmethyl)-1,3-tropolone

The reaction of 4-chloro-2,7,8-trimethylquinoline with 4,6-di(tert-butyl)-3-(piperidin- 1-ylmethyl)-1,2-benzoquinone, which was prepared by the in situ oxidation of 4,6-di(tert- butyl)-3-(piperidin-1-ylmethyl)pyrocatechol with sodium nitrite, gave 4,6-di(tert-butyl)-2- (4-chloro-7,8-dimethylquinolin-2-yl)-7-(piperidin-1-ylmethyl)-1,3-tropolone. Its structure was determined by X-ray diffraction. The energy and structural characteristics of the tauto- mers of this compound in the gas phase and in a polar solution were calculated by quantum chemical methods (PBE0/6-311+G(d,p)).

Hierarchical self-assembly of a small monomer with two orthogonal binding sites: from discrete hexagonal containers to a stimuli-responsive supramolecular gel

A small self-complementary monomer 1 is described, with two orthogonal binding interactions based on ion pairing and metal-ligand coordination, which is reversibly switchable between monomer, cyclic oligomers as well as linear- and 3D-netlike polymers in polar solution (DMSO). The aggregation was studied by atomic force microscopy, transmission electron microscopy, helium ion microscopy (HIM) and diffusion ordered spectroscopy (DOSY NMR). First, at lower concentrations, hexagonal cyclic containers are formed, whereas at higher concentrations hierarchical self-assembly leads to a metallogel. This gel can be switched between the sol/gel-state using different stimuli like pH, temperature changes or the addition of metal and metal-chelators, respectively. The supramolecular gel is rather stable and shows interesting shear thinning behavior.

A New Method for Treating Drude Polarization in Classical Molecular Simulation.

With polarization becoming an increasingly common feature in classical molecular simulation, it is important to develop methods that can efficiently and accurately evaluate the many-body polarization solution. In this work, we expand the theoretical framework of our inertial extended Langrangian, self-consistent field iteration-free method (iEL/0-SCF), introduced for point induced dipoles, to the polarization model of a Drude oscillator. When applied to the polarizable simple point charge model (PSPC) for water, our iEL/0-SCF method for Drude polarization is as stable as a well-converged SCF solution and more stable than traditional extended Lagrangian (EL) approaches or EL formulations based on two temperature ensembles where Drude particles are kept "colder" than the real degrees of freedom. We show that the iEL/0-SCF method eliminates the need for mass repartitioning from parent atoms onto Drude particles, obeys system conservation of linear and angular momentum, and permits the extension of the integration time step of a basic molecular dynamics simulation to 6.0 fs for PSPC water.

Influence of Polar Solutions on the Extraction of Phenolic Compounds from Capulín Fruits (Prunus serotina)

The phenolic compounds extraction of Prunus serotina Erhr with different ratios of acetone:water, methanol:water and ethanol:wa-ter was optimized using the Taguchi method. The factors evaluated were the solvent mixture and stirring time. The total phenolic content in extracts was assessed by the Folin-Ciocalteu method using gallic acid (GA) as the standard. The maximum value was 20.3 ± 0.86 mg GAE g–1db using acetone:water (7:3, v/v) and 30 min of stirring time.

Separation of water/butan-1-ol based on activity coefficients at infinite dilution in 1,3-didecyl-2-methylimidazolium dicyanamide ionic liquid

The activity coefficients (γ13∞) at infinite dilution for 65 solutes and the effect of interaction between organic solvents or water on the interfacial and bulk properties of 1,3-didecyl-2-methylimidazolium dicyanamide, [D2MIM][DCA] were detected by the gas-liquid chromatography at six temperatures in range of (358.15–408.15) K. The data are provided for polar and non-polar solutes as alkanes, alkenes and alkynes, aromatic hydrocarbons, alcohols, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, esters as well as for water. The synthesis and the thermal properties of [D2MIM][DCA] are presented. The fundamental thermodynamic functions, the partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated and discussed. The values of selectivity and capacity for the separation problem water/butan-1-ol were calculated from γ13∞ and compared to literature values for imidazolium-based, or dicyanamide-based ionic liquids (ILs) for the same separation problem. The data presented here shows that [D2MIM][DCA] reveals attractive selectivity and capacity in the comparison to measured earlier ILs in the chosen separation problem. These findings seem useful for future applications of this IL in projects of new technologies for water/butan-1-ol separation process.

Unexpectedly Large Spin Coherence Effects in the Recombination Fluorescence from Irradiated Highly Polar Solutions on a Nanosecond Time Scale.

Spin correlation effects in the geminate recombination of radical ion pairs in irradiated highly polar liquids are typically believed to be negligible due to a high escape probability for the ions. This report presents the results of an exploratory study of organic polar solvents aimed at the searching for, and estimating the magnitude of, the time-resolved magnetic field effects (TR MFEs) in the delayed radiation-induced fluorescence from diluted solutions of a luminophore. It has been found that upon the high-energy irradiation of the solutions in polar liquids, such as dichloroethane (ε ≈ 10), methanol (ε ≈ 33), acetonitrile (ε ≈ 37), dimethylformamide (ε ≈ 37), dimethyl sulfoxide (ε ≈ 47), ethylene carbonate (ε ≈ 89), substantial spin coherence effects in the delayed fluorescence can be observed within a time range up to ∼100 ns. In most of the cases studied, magnetic resonance characteristics of primary or very early solvent-related radical ions were evaluated from the TR MFE curves. This approach can, therefore, be widely used to complement results obtained by the pulse radiolysis technique with structural and kinetic data extracted from the magnetic resonance characteristics of the short-lived radical ions formed in irradiated media.

Efficacy of esmolol cardioplegia during hypothermic ischaemia

Cardioplegic arrest using a polarizing solution has been shown to have beneficial advantages for cardioprotection compared with depolarizing (potassium-based) arrest; most studies, however, have looked at normothermic ischaemia with short infusion intervals (every 10-15 min). This study examines the protective efficacy of an esmolol-based cardioplegia during hypothermic arrest, together with a prolonged infusion interval (30 min) for increased clinical feasibility. Isolated Langendorff-perfused hearts were subjected to arrest with St Thomas' Hospital cardioplegia (STH2), or esmolol cardioplegia (single- or multidose infusion at 32°C) for 60-min, 90-min or 120-min global ischaemia at 32°C, and recovery of function (left ventricular developed pressure) measured. A further study examined the protective efficacy of multidose esmolol cardioplegia compared with hypothermia alone at temperatures of 20°C, 28°C and 32°C compared with 37°C for 120 min of ischaemia. Esmolol cardioplegic arrest with multidose infusion at 32°C significantly improved recovery of function (left ventricular developed pressure) compared with 32°C STH2, at each ischaemic duration (88 ± 3 vs 66 ± 3% at 60 min, 82 ± 3 vs 51 ± 3% at 90 min and 73 ± 6 vs 49 ± 4% at 120 min; P < 0.05). At various hypothermic temperatures, esmolol cardioplegia significantly improved protection compared with hypothermia alone (88 ± 4%, 88 ± 3% and 72 ± 3% vs 60 ± 3%, 30 ± 2% and 15 ± 1% at 20°C, 28°C and 32°C, respectively; P < 0.05); however, at 37°C, there was no difference in protection. Contracture during ischaemia mirrored the effects of left ventricular developed pressure recovery. Esmolol cardioplegia (a polarizing solution), used as a multidose infusion during hypothermia, significantly improved cardioprotection compared with the depolarizing STH2. An increased infusion interval of 30 min indicates improved clinical feasibility.

DFT study on the complexation of anions with 1,4,7,10,13,16-hexaazacyclooctodeca-2,5,8,11,14,17-hexaene

Macrocyclic compounds have been widely used as anion carriers, as they play important functions in chemical and biological systems. This work reports a theoretical study on free 1,4,7,10,13,16-hexaazacyclooctodeca-2,5,8,11,14,17-hexaene (HAC), as well as its complex with fluoride, chloride, bromide and acetate anions, with and without the presence of the sodium counterion, in the gas phase and implicit solvents (cyclohexane and acetonitrile), at the ωB97X-D/6-311G(d,p) level. The negative ∆G0 values indicate that the crown-anion complex is prone to be formed due to hydrogen bonds in all tested media. Nevertheless, such interactions weaken as the solvent polarity increases. The ΔG0 C6H12 values decrease when the counterion is taken into account, reinforcing the formation of the Na+‒HAC‒X− complex. However, the complexation is disfavored in polar solution, since the presence of the counterion increases the HAC-anion distance. Natural bond orbital analysis, the quantum theory of atoms in molecules and non-covalent interactions methods explored the nature and strength of the hydrogen bond interactions, while spin–spin coupling constant calculations for the fluoride-based complex (1h J F,H(N)) gave insight into the potential of this NMR parameter to experimentally probe the complexation of HAC with fluoride.

Trends in oxidation and buildup of conversion products of the hydroquinone–styrene epoxide–p-toluenesulfonic acid ternary system in a polar solution

Addition of 1,4-dihydroxybenzene (hydroquinone) to the styrene epoxide–para-toluenesulfonic acid binary system subjected to oxidation in a solution of 90 vol % tert-butanol with 10 vol % chlorobenzene increases the styrene epoxide consumption rate and the rate of oxygen uptake by the system and leads to buildup of benzaldehyde. The ratio of the O2 uptake rate to the overall rate of styrene epoxide consumption in the hydroquinone–styrene epoxide–para-toluenesulfonic acid ternary system is (V O2/V SE) ≈ 0.24 (343K), which is 3.5 times that for the epoxide–acid binary system.

Characterization of a dicationic imidazolium-based ionic liquid as a gas chromatography stationary phase

Here we report the characteristics of a new synthesized ionic liquid, 1,9-di(N-naphthalen-2-ylimidazolium)nonane bis[(trifluoromethyl)sulfonyl]imide ([C9(2NPTim)2][(NTf2)2]), as a stationary phase by inverse gas chromatography. The McReynolds constants demonstrated that the [C9(2NPTim)2][(NTf2)2] had an average polarity of 667 and polarity number P.N.=75, suggesting its polar nature. The solvation properties of the new stationary phase were determined by the calculation of Abraham solvation system constants, whereby the results showed that its major interactions with the analytes included H-bond basicity (a), dipole–dipole (s) and dispersive (l) interactions. The activity coefficients (γ∞) and selectivities (SIJ∞) at infinite dilution were also determined for various polar and nonpolar organic solutes at different temperatures. The separation performance of the [C9(2NPTim)2][(NTf2)2] stationary phase was evaluated by GC separations of different analytes, including normal alkanes and aromatic compounds. The TGA results showed that the stationary phase had high thermal stability up to 420°C.

Using force-based adaptive resolution simulations to calculate solvation free energies of amino acid sidechain analogues.

The calculation of free energy differences is a crucial step in the characterization and understanding of the physical properties of biological molecules. In the development of efficient methods to compute these quantities, a promising strategy is that of employing a dual-resolution representation of the solvent, specifically using an accurate model in the proximity of a molecule of interest and a simplified description elsewhere. One such concurrent multi-resolution simulation method is the Adaptive Resolution Scheme (AdResS), in which particles smoothly change their resolution on-the-fly as they move between different subregions. Before using this approach in the context of free energy calculations, however, it is necessary to make sure that the dual-resolution treatment of the solvent does not cause undesired effects on the computed quantities. Here, we show how AdResS can be used to calculate solvation free energies of small polar solutes using Thermodynamic Integration (TI). We discuss how the potential-energy-based TI approach combines with the force-based AdResS methodology, in which no global Hamiltonian is defined. The AdResS free energy values agree with those calculated from fully atomistic simulations to within a fraction of kBT. This is true even for small atomistic regions whose size is on the order of the correlation length, or when the properties of the coarse-grained region are extremely different from those of the atomistic region. These accurate free energy calculations are possible because AdResS allows the sampling of solvation shell configurations which are equivalent to those of fully atomistic simulations. The results of the present work thus demonstrate the viability of the use of adaptive resolution simulation methods to perform free energy calculations and pave the way for large-scale applications where a substantial computational gain can be attained.

High-level Ab Initio Absorption Spectra Simulations of Neutral, Anionic and Neutral+ Chromophore of Green Fluorescence Protein Chromophore Models in Gas Phase and Solution.

Semiclassical ab initio simulations of the absorption spectra of neutral and anionic p-hydroxybenzylidene-2,3-dimethylimidazolinone (p-HBDI), a model chromophore of green fluorescent protein (GFP) and of a positively charged neutral (N+)-HBDI chromophore model, were performed in gas phase with the resolution-of-identity algebraic diagrammatic construction through second-order (RI-ADC(2)) method. The calculated absorption spectra in gas phase are composed of one band centered at 3.51 eV (HBDI), 2.50 eV (HBDI- ) and 3.02 eV ((N+)-HBDI) owing to the absorption of the first 1 ππ* transition. Band maxima are redshifted by ~0.1 eV with respect to the corresponding vertical energies. The COSMO-RI-ADC(2) calculations of the first vertical excitation energy of HBDI, HBDI- and (N+)-HBDI forms in polar solution including microsolvation simulate the observed solvent redshift for neutral HBDI and the solvent blueshift of the HBDI- and (N+)-HBDI forms. The state-specific solvation approach applied to TDDFT calculations reproduced the experimental solvent shifts for the three HBDI forms, demonstrating a more accurate theoretical description as compared to the linear-response TDDFT approach.

Separation of water/butan-1-ol mixtures based on limiting activity coefficients with phosphonium-based ionic liquid

In the present work the limiting activity coefficients (γ13∞) for 64 solutes, including polar and non-polar solutes as alkanes, alkenes and alkynes as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, and esters in the tributyltetradecylphosphonium dodecylbenzenesulfonate, [P14,4,4,4][DBS] were determined by gas-liquid chromatography at six temperatures in range of (318.15–368.15) K. Density, ρ as a function of temperature, T for chosen ionic liquid, [P14,4,4,4][DBS] at pressure p=101kPa was measured. The gas-liquid partition coefficients, KL at infinite dilution and the fundamental thermodynamic functions, the limiting partial molar excess Gibbs energy, enthalpy and entropy were calculated. The values of selectivity and capacity for water/butan-1-ol separation problem were calculated from γ13∞ and compared to literature values for phosphonium-based or other selected ionic liquids for the same separation problem. The Abraham solvation parameter model was also presented for all solutes. On the bases of the results the intermolecular interactions of the chosen IL and solutes were discussed. The data presented here shows that [P14,4,4,4][DBS] reveals the best ever measured selectivity and capacity for the for water/butan-1-ol separation.

Energetic Analysis of Adsorption and Absorption of Small Molecule to Nanodroplet of Water.

Adsorption and absorption were analyzed for nonpolar and polar solutes to a water droplet of nanometer size and to a planar slab. All-atom molecular dynamics simulation was performed, and the free energy change for bringing the solute to the water aggregate was computed over a wide range of temperature. It was seen in both the droplet and slab systems that the solute is preferably located at the surface, and the propensity of the nonpolar solute at the surface relative to the bulk was found to be larger in the droplet than in the slab. A molecular-sized curvature thus enhances the surface propensity of a nonpolar solute, whereas the curvature effect is weaker for polar one. The attractive and repulsive interactions of the solute with water were further analyzed, and the role of the repulsive interaction is discussed with respect to the stability of the surface-bound state.

High selective water/butan-1-ol separation on investigation of limiting activity coefficients with [P8,8,8,8][NTf2] ionic liquid

The limiting activity coefficients (γ13∞) for 65 solutes, including polar and non-polar solutes as alkanes, alkenes and alkynes as well as aromatic hydrocarbons, alcohols, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, esters and water in the tetraoctylphosphonium bis{(trifluomethyl)sulfonyl}imide ionic liquid (IL), [P8,8,8,8][NTf2] were determined by gas-liquid chromatography at six temperatures in range of (318.15–368.15) K. The synthesis and DSC data are presented for this IL. Density, ρ and viscosity, η as a function of temperature, T in a range of (298.15–398.15) K for [P8,8,8,8][NTf2] were measured at pressure p = 101 kPa. The gas-liquid partition coefficients, KL at infinite dilution and the thermodynamic functions, the limiting partial molar excess Gibbs energy, enthalpy and entropy were calculated. The values of selectivity and capacity for water/butan-1-ol separation problem were calculated from γ13∞ and compared to literature values for phosphonium-based or other selected ionic liquids for the same separation problem. The Abraham solvation parameter model was also presented for all solutes. On the basis of the results, the intermolecular interactions of the chosen IL and solutes were discussed. The data presented here show that [P8,8,8,8][NTf2] reveals very large selectivity for the water/butan-1-ol separation.

Photoelectrons in the quiet polar wind

AbstractThis study presents a newly coupled model capable of treating the superthermal electron population in the global polar wind solution. The model combines the hydrodynamic Polar Wind Outflow Model (PWOM) with the kinetic SuperThermal Electron Transport (STET) code. The resulting PWOM‐STET coupled model is described and then used to investigate the role of photoelectrons in the polar wind. We present polar wind results along single stationary field lines under dayside and nightside conditions, as well as the global solution reconstructed from nearly 1000 moving field lines. The model results show significant day‐night asymmetries in the polar wind solution owing to the higher ionization and photoelectron fluxes on the dayside compared to the nightside. Field line motion is found to modify this dependence and create global structure by transporting field lines through different conditions of illumination and through the localized effects of Joule heating.