Dipole Moment Of Solvent Research Articles

1-Amino 2-Naphthol Modified Solvent Filled Carbon Nanotubes for Enhanced Electrochemical Sensing of Bioanalytes

Our research interest is mainly on developing cost-effective electrochemical sensors for bioanalytes sensing. For example, bioanlytes such as ascorbic acid, dopamine, and uric acid present together in human body poses challenge for selective sensing of one over other. As these molecules play a vital role in controlling the body’s metabolism, it is paramount to develop a sensor tool with high sensitivity towards these bioanlytes for diagnosing diseases, including AIDS, Parkinsonism, etc. Development of fast and reliable methods for sensing these biomolecules is of considerable importance in offering rapid diagnosis.1–3 In the present experimental work, it is shown for the first time that liquid-filled multi-walled carbon nanotubes (MWCNTs) exhibit remarkably enhanced characteristics for sensor applications, the detection threshold being lowered by as much as an order of magnitude, while detection sensitivity is doubled for a number of molecules including ascorbic acid, dopamine, and uric acid. 1H NMR relaxometry at a moderately low field, i.e., 14.6 MHz (0.34 T), confirms that the improved sensor characteristics are correlated with the filling of MWCNTs with solvents such as acetonitrile, dimethyl sulfoxide, etc. The molecular motions are slowed down when solvent molecules fill MWCNTs, thus increasing motional correlation times, and hence, longitudinal relaxation rate increases under extreme narrowing conditions. The filling of MWCNTs appears to relate to solvent-CNT interactions that are in line with the principle of hard and soft acids and bases, and also correlates with solvent dipole moments.4 We have further enhanced the detection limit and selectivity towards ascorbic acid by modifying the MWCNTs surface with amino naphthol.

Performance of all-solution-processed, durable 2D MoS2 flakes−BaTiO3 nanoparticles in polyvinylidene fluoride matrix nanogenerator devices using N-methyl-2-pyrrolidone polar solvent

Piezoelectric nanogenerator (PENG) is an alternative sustainable solution by transforming surrounding mechanical energy into electrical power. In this work, the optically transparent and mechanically flexible PENG devices were fabricated using simple all-solution-processed techniques. The device was constructed using spin- and spray coating methods to form the structure of silver nanowires/nanocomposite/poly (3,4-ethylenedioxythiophene) polystyrene sulfonate. The nanocomposite is a blending of barium titanite nanoparticles and molybdenum disulfide flakes in the polyvinylidene fluoride matrix. PENG devices were prepared with dimethylformamide (DMF) and N-Methyl-2-pyrrolidone (NMP) solvents, respectively to examine the influence of the solvents towards the output voltage. It is found that the PENG device prepared with the NMP solvent generated a voltage of 750 mV, significantly higher output voltage than the PENG device prepared by DMF, which is about 100 mV. The probable reasons could be the higher dipole moment of NMP solvent, interaction, and intercalation of MoS2 flakes in the PVDF polymer chain matrix. An automated self-tapping machine was designed to perform the endurance study. The device was able to generate stable 1.5 V of peak-to-peak voltage up to 5000 cycles in a total 5-day intermittent test without significant degradation. The PENG device prepared in the NMP solvent maintained at least 95% of its 1.5 V throughout the whole testing cycle.

Preparation of PVDF flexible piezoelectric film with high β-phase content by matching solvent dipole moment and crystallization temperature

In Poly(vinylidene fluoride) (PVDF) polymer films, α-phase usually dominates and leads to weak electrical properties, limiting its applications in microelectronics. In this paper, the effects of dipole moment of the solvent and the crystallization temperature on β-phase content in PVDF films have been systematically investigated. Variations in crystalline phases were confirmed by using X-ray diffractometer (XRD), Fourier transform infrared spectra (FTIR) and differential scanning calorimetry (DSC). The results verified that larger dipole moment of the solvent is more beneficial to the formation of β-phase in PVDF films. PVDF films with high content of β-phase up to 98.8% are obtained by using dimethylsulfoxide (DMSO) as the solvent at optimized crystallizing temperature of 60 °C. The corresponding PVDF film with high β-phase content presents excellent ferroelectric and piezoelectric properties, with a remnant polarization (Pr) and piezoelectric coefficient (d33) of 7.7 μC/cm2 and − 25.8 pC/N, respectively. It is worth mentioning that this high d33 compares that of the expensive PVDF-based copolymers and complexes. The process displayed in this research provided a feasible method to the preparation of low cost PVDF films for flexible piezoelectric sensors and actuators.

Electrolyte Dependency on Ca2+ Insertion/Extraction Properties of V2O5

Recently, calcium ion batteries (CIBs) have been attracting attention as next-generation batteries because of their higher energy density, higher safety, lower costs and more abundant elements than lithium ion batteries (LIBs). On the other hand, CIBs have several problems impeding their progress. One critical issue is the development of a suitable organic electrolyte without a negative impact on the electrochemical properties of the electrode material. In our past study, we reported that the overvoltage decreased when water was added to the electrolyte1. One reason for the decrease of overvoltage is a change in the electrolyte structure such as the solvation structure and the degree of salt dissociation. In this study, we investigated the electrolyte structure with varied organic solvent species and salt concentration, and examined the electrolyte dependency on Ca2+ insertion and extraction properties of V2O5. We used Ca(TFSI)2 as the electrolyte salt, which was vacuum dried at 150℃ for 12h before use. For the organic solvents, EC: DMC (1:1 in vol.), EC: PC (1:1 in vol.), triglyme (G3) and acetonitrile (AN) were used. The concentration of electrolyte was adjusted to 0.2-0.5 molL-1.V2O5 nano-sheet synthesized by hydrothermal-assisted method2 was used as the working electrode. The electrode was prepared by mixing the synthesized V2O5, acetylene black and polyvinylidene difluoride dissolved in N-methyl-2pyrrolidinone with a weight ratio of 70:20:10, then coated onto a carbon coated titanium foil and vacuum dried at 120℃ overnight. A constant current discharge-charge experiment was performed at 0.05C-1C. The results of electrolyte structure analysis showed that the contact ion pair (CIP) decreased as the dipole moment of the organic solvent decreased except for G3. When G3 was used, it is considered that the solvent-separated ion pair (SSIP) was formed because of the small dipole moment of G3. Interestingly, a decrease in the amount of CIP due to the decrease of concentration was observed when using EC: DMC or EC: PC, but not when using G3 or AN. The results of the constant current discharge-charge experiment were strongly related to the amount of CIP. The coulombic efficiency tended to improve as the amount of CIP decreased except for using G3, in particular, a high coulombic efficiency of 95% was shown when using 0.3M Ca(TFSI)2/EC: DMC. As a factor of the instability of electrolyte when G3 was used, Ca2+(G3)TFSI- SSIP may also be reductively unstable as Ca2+TFSI- CIP. On the other hand, G3-based electrolyte showed the lowest overvoltage and the best rate performance. According to the surface analysis of the electrode after the test, the concentration of calcium in the surface film was less than that for other solvents. It suggests that the nature of the surface film may be related to a decrease in the overvoltage. When a solvent other than G3 was used, the overvoltage decreased as the amount of CIP decreased, and a relatively high rate performance was obtained for 0.3 molL-1 Ca(TFSI)2/EC: DMC, similar to the tendency of coulombic efficiency. Reference s : [1] Y. Murata et al., Electrochim. Acta 294 (2019) 210-216. [2] H. Song et al., J. Power Sources 294 (2015) 1-7.

Exploration the inherent mechanism of polymorphism and mechanochromism based on isomerism and AIE theory

Polymorphism plays an important role in the fields of drugs, pigments and multicolor conversion materials, however, obtaining polymorphism mainly depend on accident and fortune until now. To explore the intrinsic mechanism of polymorphism and mechanochromism, TPEB2T and TPEB3T were designed and synthesized based on isomerism effect and aggregation-induced emission (AIE) theory. Photo-physical properties of the two complexes indicate they exhibit solvent-dependent fluorescence spectra, similar AIE property and markedly different mechanochromism and polymorphism. By diffusion n-hexane into dichloromethane solution of luminogens, the crystals of TPEB2T (2O) and TPEB3T (3Y and 3O) were obtained. The emission maxima of crystals 2O, 3O and 3Y display 23, 40 and 66 nm red-shift respectively after grinding, accompanied by significantly enhanced fluorescence quantum efficiency for 3Y from 0.09 to 0.39 and over 50% decline for 2O and 3O. Compared with 2O and 3O, the high contrast mechanochromism and weak emission intensity for crystal 3Y were attributed to different intermolecular head to head overlap rather than heavy atom effect of sulfur based on single crystal analysis and theoretical calculation. By extracting molecular pairs from crystals and constructing hypothetical molecular pairs based on molecular isomerization between sulphur and boron atoms, the minimum energy and dipole moment calculation results reveal that the formation polymorphism mainly depend on dipole moment of molecular pairs and culture solvent.

Structural changes in copper based metal-organic framework catalyst induced by organic solvents

Abstract Metal-organic frameworks (MOFs) are an emerging class of catalysts that posess large surface area due to intrinsic porosity, and high metal loading. However, they often lack catalytic properties due to the saturated coordination sphere of metal centres. Some MOFs have been found to exhibit good to excellent catalytic activity in a limited number of reactions, resulting from solvent induced changes of the coordination sphere. In this work the coordination sphere changes of Cu(bpy)(H2O)2(BF4)2(bpy) (bpy = 4,4-bipyridine) affected by common solvents with different dipole moments were studied by means of solution-state 1H and 19F NMR. It was found that organic molecules interact with the copper(II) centre and cause structural transformations of Cu-MOF in proportion to both the dipole moment and concentration of solvent. The sensitive NMR resonances reveal an exchange of the BF4¯ anions to DMSO (dimethylsulfoxide) molecules at axial positions of Cu(II) and even breakage of Cu-N and Cu-O bonds in equatorial positions with increasing DMSO concentration. Therefore, solvents with suitable dipole moments (1.7–3.9) can promote structural changes and, thus release highly active sites in the reaction, which can efficiently enhance the activity of Cu-MOF catalysts.

Electrochemical Sensors Using Liquid Filled Multiwalled Carbon Nanotubes: Enhanced Sensor Characteristics, and NMR Relaxometry Evidence of Liquid Confinement

In the present experimental work, it is shown for the first time that liquid filled multi-walled carbon nanotubes (MWCNTs) exhibit remarkably enhanced characteristics for sensor applications, the detection threshold being lowered by as much as an order of magnitude, while detection sensitivity is doubled for a number of molecules including ascorbic acid, dopamine, and uric acid. The sensitivity obtained for DA is 84 μA mM−1 (linear range 3 to 30 μM) detection limit is 1.6 μM. NMR relaxometry at a moderately low field confirms that the improved sensor characteristics are correlated with the filling of MWCNTs with solvents such as acetonitrile, dimethyl sulfoxide, etc., such confinement resulting in increased solvent relaxation rates. The filling of MWCNTs appears to relate to solvent-CNT interactions that are in line with the principle of hard and soft acids and bases, and also correlates with solvent dipole moments.

Effect of solvent polarity in mechanochemistry: preparation of a conglomerate vs. racemate.

Cocrystallization of racemic dl-tartaric acid (dl-ta) and achiral isoniazid (ISN) was investigated using mechanochemistry. Neat grinding (NG) and liquid-assisted grinding (LAG) in the presence of non-polar liquids result in the formation of a conglomerate (ISN·d-ta/ISN·l-ta); whereas LAG with polar liquids yields racemic salt ISN·dl-ta. The effect of solvent polarity and dipole moment in mechanochemistry is discussed.

Ate-complexes of tris-dioxolene tin anion with nickel (or cobalt) bis-(2,2ʹ-dipyridine)-dioxolene cation. EPR study of spin migration dynamics. Solvent and counterion effects

Reaction of bis-o-semiquinonato nickel complex (2,2ʹ-dipyridine)Ni(dioxolene)2 (1) (dioxolene here – mono- or double-reduced forms of 3,6-di-tert-butyl-o-benzoquinone) or its cobalt analogue (2,2ʹ-dipyridine)Co(dioxolene)2) with (2,2ʹ-dipyridine)Sn(dioxolene)2 occur through ligands exchange and results in ate-complex [(2,2ʹ-dipyridine)2M(dioxolene)]+ [Sn(dioxolene)3]- (M = Ni (2), Co(3)). According to single crystal x-ray diffraction study both products are isostructural. Geometry of tin anion is intermediate between octahedral and trigonal prism. Analysis of bonds lengths in chelate cycles in tin anion one of dioxolene ligands is semiquinone anion-radical whereas the other two are catecholato-dianions. Geometry of inner coordination core of both cations is close to octahedral. Cobalt being in 3+ oxidation state is connected to catecholato-dianion. Nickel being in 2+ oxidation state is connected to semiquinonato anion-radical. Variable temperature magnetic susceptibility measurements of 2 indicate high spin nickel ferromagnetically coupled with semiquinonato anion-radical connected to it and independent semiquinone coordinated to tin. Cobalt cation is diamagnetic. EPR studies of ate-complex 3 in solution indicate two independent dynamic processes: solvation and migration of unpaired electron between three structurally identical ligands. Rate of this migration depends on solvent and temperature: from slow (CCl4, toluene) to fast (MeOH, CH3CN) in EPR time scale. Solvent role is solvation of the tin anion on one hand and the extent of isolation of ions: from “close pair” in CCl4 to “solvate separated pair” in methanol on the other hand. It is determined by solvent permittivity and dipole moment. Temperature dependence of hyperfine coupling constant with tin magnetic nuclei allowed estimating enthalpy and entropy of solvation. Temperature dependence of EPR spectrum shape together with it simulation allowed to evaluate the rates of spin migration and it activation parameters. In general, the regularities of ate-complex 2 behavior are the same but EPR lines are broader because of presence of high spin nickel and cation polarity effect is less than that in 3 because of smaller charge separation.

Enhanced Output Performance of P(VDF-TrFE) Based Energy Harvesters with Controlled Dipole Moment of Solvents

Wireless sensor networks (WSN) in the form of spatially distributed sensors monitor various environmental activities such as chemical, biological, tactile, acoustic, navigational, and thermal data, and communicate the information to a central station to perform corrective measures. They can therefore greatly benefit human society in terms of healthcare, environmental sensing, and industrial monitoring. Powering the enormous number of sensor nodes in a network is a considerable challenge. Batteries however do not offer a viable solution, as they have a limited lifetime. Indeed, the number of required battery replacements could be unbelievably high. In order to circumvent the challenge, energy harvesters, which harvest the energy from the working environment of a sensor through piezoelectric, pyroelectric, and triboelectric phenomena, are proposed. Energy harvesters have therefore received enormous attention in order to provide a self-powered operation of sensors for WSNs and Internet of Things (IoT) applications. The poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)), being a ferroelectric polymer, has great promise for energy harvesting for flexible and wearable applications. In this paper, we have shown that the choice of solvent that is utilized to dissolve the polymer significantly influences its properties in terms of energy harvesting. Indeed, the P(VDF-TrFE) prepared using a high dipole moment solvent has higher piezoelectric and pyroelectric coefficients, and triboelectric property. Such improvements are the result of higher crystallinity and better dipole alignment of the polymer prepared using a higher dipole moment solvent. Tetrahydrofuran (THF), methyl ethyl ketone (MEK), dimethyl formamide (DMF), and dimethyl sulfoxide (DMSO), at 20 °C with dipole moments of 1.75 D, 2.7 D, 3.8 D, and 4.1 D, respectively, were considered as solvents. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) measurements were carried out to investigate the crystallinity of the polymer due to the different solvents. Gel permeation chromatography (GPC) measurements were utilized to measure the relative chain length of P(VDF-TrFE). In addition, the dipole alignment of P(VDF-TrFE) with various solvents was measured using piezoelectric force microscopy (PFM). In order to investigate the solvent effect on the performance of the energy harvesters, we measured the piezoelectric and pyroelectric coefficients, and triboelectric property in terms of the contact potential difference (CPD) of the P(VDF-TrFE), using PFM and kelvin probe force microscopy (KPFM) techniques, respectively. Furthermore, in order to study the piezoelectric, pyroelectric, and triboelectric potential distribution of the various solvent-based P(VDF-TrFE)-based generators, finite element method (FEM) simulations were carried out in COMSOL. Finally, P(VDF-TrFE) based piezoelectric, pyroelectric and triboelectric generators experimentally validate that the higher dipole moment solvent significantly enhances the output performance of the energy harvesters; the improvement was 23.18 %, 81.82 % in output voltage and current, respectively, for piezoelectric generator; 39.60 %, 34.11 % in output voltage and current, respectively, for pyroelectric generator; and 65.24 % and 75.06 % in output voltage and current for triboelectric generator. In brief, the approach of utilizing high dipole moment solvent is very promising for high output P(VDF-TrFE) based wearable energy harvesters. Figure 1

Polarization Effects in Binary [BMIM+][BF4-]/1,2-Dichloroethane, Acetone, Acetonitrile, and Water Electrolytes.

Organic electrolytes are unique in that their constituent solvents may be of much lower dielectric strength than water. This is because the ions of organic electrolytes are often those that comprise room-temperature ionic liquids, which are surprisingly miscible with many different organic solvents of low dielectric strength. Strong ion correlation results from the relatively low dielectric screening of the solvent, resulting in properties that can substantially deviate from Debye-Huckel descriptions; in addition remains the fundamental question of why the ionic liquids and low dielectric solvents are even miscible in the first place. In this work, we study electrolyte mixtures composed of the room-temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM+][BF4-] mixed with four solvents of systematically varying dielectric strength, 1,2-dichloroethane, acetone, acetonitrile, and water. We show that miscibility with the lowest dielectric solvent, dichloroethane, is directly attributed to ion solvation enhancement mediated by both electronic and conformational polarization of the solvent molecules. A strong dielectric enhancement results from the ∼70-80% increase in solvent dipole moments at high ion content, providing significantly better solvation than predicted by the bulk solvent dielectric strength. This implies a general mechanism for miscibility of ionic liquids with low dielectric solvents, through which ions effectly create their own solvation dipoles by polarizing the local environment. From a purely computational perspective, our results imply that explicitly polarizable force fields are essential for modeling many of the organic electrolytes that are used in electrochemical applications.

Effect of solvent induced dielectric property modulation of poly(methyl methacrylate) insulator on the electrical and photosensing behaviour of p-channel organic transistors

We have investigated the influence of solvent dipole moment on the dielectric properties of poly(methyl methacrylate) (PMMA) gate dielectric and unravel its effect on the OFET performance, environmental stability, and photosensitivity. The device performance improved substantially upon the use of high dipole moment solvents, however, it was also observed that such solvents can exacerbate the operational stability of the transistors. A detailed investigation of polymer bulk and surface properties revealed that the choice of solvents can strongly influence its micro-molecular structure, dipolar orientation and surface chemical composition which consequently, affect the device performance and stability by controlling the leakage characteristics, capacitance density, trap formation mechanism and charge trapping behaviour at dielectric/semiconductor interface. This report illustrates the requirement of proper solvent selection to achieve high electrical performance as well as long term operational stability. Our study also demonstrates that low dipole moment solvents are more favourable in transistors for photo-detection applications.

Effects of solvent on structures and properties of electrospun poly(ethylene oxide) nanofibers

ABSTRACTPoly(ethylene oxide) (PEO) nanofibers were prepared by electrospinning PEO solution with a mixed solvent of ethanol and deionized water. The results show that the mixed solvent system has noteworthy influences on structures and properties of electrospun PEO nanofibers, including molecular chain orientation, crystallinity degree, surface morphology, fiber diameter, diameter distribution, spinnability, and productivity. With increasing ethanol content in the mixed solvent, wrinkly morphologies appear on the surface of PEO nanofibers due to a high evaporation rate of ethanol during electrospinning process. The dielectric constant, dipole moment, conductivity, density, boiling point, and solubility parameter of the mixed solvent become lower with the ethanol content increasing. Besides, the hydrogen‐bonding interactions between PEO and solvents become weaker. As a result, PEO nanofibers with larger diameters, lower molecular chain orientation, and crystallinity degree are obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45787.

Organic analytes sensitivity in meso-porous silicon electrical sensor with front side and backside contacts

Chemical sensors fabricated from porous silicon (PSi) for liquid organic analytes (ethanol, acetonitrile, methanol and acetone) are demonstrated, with an emphasis on the impact of the Ag electrical contact placement on sensor performance. Sensors with front side contact display larger shift in capacitance response (2–3 times more sensitive) compared to the backside sensor design as the solvents immediately interact with the pore openings before infiltration. Much slower response time (7–30 min range) for front side vs. (50–200 s scale range) for backside configuration is observed. Both sensor designs exhibit excellent solvent infiltration-evaporation reversible response, indicating no chemical reaction or surface modification occurred. The response time was in the order of ethanol>acetonitrile>methanol>acetone, which correlates well with the solvent vapor pressure. The capacitance shift in both sensor devices is likely related to the interface interaction, revealing a closer correlation with the dipole moments of solvents. This is supported by the photoluminescence quenching upon exposure to organic solvents, with a relative intensity decrease tracks with the dipole moment. The sensitivity remains sufficiently high during the repeated use, with excellent storage stability for backside contact. This comparative study suggests the viability of the current sensor structure and design particularly with backside contact for sensing of various chemical analytes with notably sensitivity and extremely rapid response.

Effect of solvents on the crystal formation of poly(vinylidene fluoride) film prepared by a spin-coating process

The effect of the solvent evaporation rate and solvent type on the crystal formation of poly(vinylidene fluoride) (PVDF) prepared by spin-coating was evaluated over time. In the much-solvent-remaining state, the crystalline phase of PVDF changed in the order of α, γ and β with the increasing dipole moment of the solvent. In the almost-all-solvent-evaporated state, the crystalline structure of PVDF/hexamethylphosphoramide with a higher dipole moment was dominantly dependent on the evaporation rate and varied in the order of β, γ and α with the increasing solvent evaporation rate. However, PVDF/triethyl phosphate, having a lower dipole moment, always formed the α phase, regardless of the evaporation rate. The PVDF α phase in the concentrated solution state is difficult to transform into the β and γ phases because the potential energy of each PVDF crystalline phase increases in the order of α, γ and β. The PVDF crystalline phase in the spin-coating method is strongly affected by both the polymer–solvent electrostatic interactions and the evaporation conditions. From the results of the crystal transition behavior, it was experimentally supported that the potential energy of the PVDF crystalline structure increases in the order of α, γ and β. The crystalline phase of PVDF film prepared by spin-coating changes both of the polymer–solvent interaction and the evaporation rate. In the much solvent remained state, the crystalline phase changes in the order of α, γ and β phase with increasing the dipole moment of solvent. In the solvent-evaporated state, the crystalline phase of PVDF and solvent with higher dipole moment system changes in the order of β, γ and α phase with increasing the solvent evaporation rate, whereas the PVDF and solvent with lower dipole moment system forms into α phase regardless of the evaporation rate.

Solvent Polarity Governs Ion Interactions and Transport in a Solvated Room-Temperature Ionic Liquid.

We explore the influence of the solvent dipole moment on cation-anion interactions and transport in 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl), [BMIM+][Tf2N-]. Free energy profiles derived from atomistic molecular dynamics (MD) simulations show a correlation of the cation-anion separation and the equilibrium depth of the potential of mean force with the dipole moment of the solvent. Correlations of the ion diffusivity with the dipole moment and the concentration of the solvent were further demonstrated by classical MD simulations. Quasi-elastic neutron scattering experiments with deuterated solvents reveal a complex picture of nanophase separation into the ionic liquid-rich and solvent-rich phases. The experiment corroborates the trend of concentration- and dipole moment-dependent enhancement of ion mobility by the solvent, as suggested by the simulations. Despite the considerable structural complexity of ionic liquid-solvent mixtures, we can rationalize and generalize the trends governing ionic transport in these complex electrolytes.

Solvent, temperature and concentration effects on the optical rotatory dispersion of (R)-3-methylcyclohexanone

Optical rotatory dispersion (ORD) spectra are reported for isolated and solvated (R)-3-methylcyclohexanone (R-3MCH) in 10 solvents, of wide polarity range, and over the spectral range 350–650 nm. Sample concentration effects on ORD spectra of R-3MCH were also recorded and investigated over widely varying concentrations from 2.5 × 10−3 to 2.5 × 10−1 g/mL where an observed sensitivity of optical rotation (OR) to incident light wavelength at low concentrations is correlated to solvent effects. Temperature effects were also studied by recording ORD spectra over the temperature range 0–65 °C in toluene. Recorded specific OR was plotted against various solvent parameters, namely, dipole moment, polarity, refractive index and polarizability to probe solvent effects. Furthermore, solvent effects were studied by incorporating Kamlet's and Taft's solvent parameters in the multi-parametric linear fitting. Theoretically, ORD spectra and populations of optimized geometries of equatorial and axial conformers of R-3MCH were calculated in the gas and solvated phases. All theoretical calculations were performed employing the polarizable continuum model using density functional theoretical and composite scheme (G4) methods with aug-cc-pVTZ and aug-cc-pVDZ basis sets. Net ORD spectra of R-3MCH were generated by the Boltzmann-weighted sum of the contributions of the dominant conformers. Upon comparing theoretical and experimental ORD spectra, a very good agreement is observed for the ORD spectra in the gas phase and high polarity solvents compared to relatively lesser agreement in low polarity solvents.

Thermodynamics of DL-α-aminobutyric acid induced solvation mechanism in aqueous KCl solutions at 288.15–308.15 K

The solubilities of DL-α-aminobutyric acid in KCl solutions of different concentrations are measured at 288.15–308.15 K. Gibbs energies and entropies have been determined for transfer of α-aminobutyric acid form water to aqueous KCl solution at 298.15 K. The cavity, dipole-dipole and other interactions affecting the solubility, as well as stability of the amino acid in solution are also evaluated. Gibbs energy and entropy of transfer due to interactions are computed to create the model of the complex solute-solvent and solventsolvent interactions. Molar volume, densities, dipole moment of solvent and diameter of co-solvent in aqueous potassium chloride are also evaluated.

The coalescence of polystyrene in correlated binary solvents

ABSTRACTThe solution behavior of solvophobic polymers is crucial to the development of polymer coatings and polymeric drug delivery vehicles. In this article, the role of dipolar interactions is investigated in the solvophobic coalescence of polystyrene in binary correlated polar solvent mixtures. A simple model for coalescence thermodynamics is derived from correlations between thermally rotating dipole moments in the solvent. The stabilizing correlations lost to the solvent due to a solute's presence give rise to a driving force for the coalescence of solutes. This stabilization is offset by the entropy of mixing that favors the dispersion of solutes. Predictions are compared to the measured point of coalescence of polystyrene in acetone when different alcohols are titrated. The model is shown to capture this point of coalescence and conformation for a variety of systems. Our results suggest the significant property determining the solubility of nonpolar polymers in a polar liquid is a free energy resulting from attractive dispersion interactions between thermally rotating solvent dipole moments. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 948–955

Influence of asymmetric depletion of solvents on the electric double layer of charged objects in binary polar solvent mixtures.

For binary solvent mixtures composed of ions and two kinds of polar solvents, the electric double layer near a charged object is strongly affected by not only the binary solvent composition but also the nature of the solvents, such as the volume and dipole moment of the solvent molecule. Accounting for the difference in sizes of solvents and the orientational ordering of solvent dipoles, we theoretically obtain general expressions for the spatial distribution functions of solvents and ions, in planar geometry and within the mean-field approach. While focusing on long-range electrostatic interaction and neglecting short-range interactions such as preferential solvation, our approach predicts an asymmetric depletion of the two solvents from the charged surface and a behavior of decreased permittivity of the binary solvent mixture. Furthermore, we suggest that the key factor for the depletion is the ratio of the solvent dipole moment to the solvent volume. The influence of the binary solvent composition, the volume of solvent and the dipole moment of the solvent on the number density of solvents, the permittivity and the differential capacitance is presented and discussed. We conclude that accounting for the difference in the volume and dipole moment between polar solvents is necessary for a new approach to represent more realistic situations such as preferential solvation.