Showing papers on "Acetonitrile published in 2012"
TL;DR: The effect of short-chain alcohols and acetonitrile on the ligand shell composition and the photoluminescence quantum yield of purified PbSe and CdSe quantum dots is analyzed and the importance of using aprotic nonsolvents for nanocrystal purification or processing is stressed.
Abstract: The effect of short-chain alcohols and acetonitrile on the ligand shell composition and the photoluminescence quantum yield of purified PbSe and CdSe quantum dots is analyzed by solution NMR and photoluminescence spectroscopy. We find that short-chain alcohols induce the release of X-type carboxylate ligands with a concurrent reduction of the photoluminescence quantum yield, while acetonitrile does not. We interpret this difference in terms of the protic or aprotic character of both nonsolvents, where only the protic alcohols can provide the protons needed to desorb carboxylate ligands. We find similar differences between short-chain alcohols and acetonitrile when used as nonsolvents during the purification of crude synthesis products, a result stressing the importance of using aprotic nonsolvents for nanocrystal purification or processing.
219 citations
TL;DR: This comparison shows that carboxylate groups positioned to act as proton delivery relays can substantially enhance the selectivity of ORR catalysis.
Abstract: Iron(III) meso-tetra(2-carboxyphenyl)porphine chloride (1) was investigated as a soluble electrocatalyst for the oxygen reduction reaction (ORR) in acetonitrile with [H(DMF)+]OTf–. Rotating ring-disk voltammetry, spectroelectrochemistry, and independent reactions with hydrogen peroxide indicate that 1 has very high selectivity for reduction of O2 to H2O, without forming significant amounts of H2O2. Cyclic voltammetric measurements at high substrate/catalyst ratios (high oxygen pressure) allowed the estimation of a turnover frequency (TOF) of 200 s–1 at −0.4 V vs Cp2Fe+/0. This is, to our knowledge, the first reported TOF for a soluble ORR electrocatalyst under kinetically controlled conditions. The 4-carboxyphenyl isomer of 1, in which the carboxylic acids point away from the iron center, is a much less selective catalyst. This comparison shows that carboxylate groups positioned to act as proton delivery relays can substantially enhance the selectivity of ORR catalysis.
192 citations
TL;DR: The CoII(qpy)(OH2)2+ complex as discussed by the authors is an efficient visible light-driven catalyst for both water oxidation and reduction, and it can be used to generate hydrogen from water at pH 8.0.
Abstract: The complex [CoII(qpy)(OH2)2]2+ (qpy = 2,2′:6′,2′′:6′′,2′′′-quaterpyridine) is an efficient visible light-driven catalyst for both water oxidation and reduction. It catalyses photochemical oxygen evolution from water at pH 8.0 with [RuII(bpy)3]2+/S2O82− (λ = 457 nm, max TON = 335, bpy = 2,2′-bipyridine). It also catalyses photochemical hydrogen generation from [IrIII(dF(CF3)ppy)2(dtbbpy)]+/TEOA (dF(CF3)ppy = anion of 2-(2,4-difluorophenyl)-5-trifluoromethylpyridine, dtbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine, TEOA = triethanolamine) in aqueous acetonitrile (λ > 420 nm, max TON = 1730).
183 citations
TL;DR: An overview of HILIC separation systems can be found in this paper, where the authors compare it to several other recently described modes, such as liquid chromatography, aqueous-organic mobile phases, and liquid-closet chromatography.
Abstract: In the early 1990s, hydrophilic interaction (liquid) chromatography (HILIC) emerged as a new separation method. HILIC is becoming increasingly popular for the separation of polar compounds in aqueous-organic mobile phases rich in organic solvents (usually acetonitrile). It has become important for the separation of pharmaceuticals, neurotransmitters, nucleosides, nucleotides and other compounds. This review presents an overview of HILIC separation systems, comparing it to several other recently described modes.
134 citations
TL;DR: The neat PIL was found to exhibit good performances as promising electrolyte for supercapacitor applications and the temperature dependence of viscosity and conductivity can be described by the VTF equation.
Abstract: This study describes the preparation, characterization and application of [Et3NH][TFSA], either neat or mixed with acetonitrile, as an electrolyte for supercapacitors. Thermal and transport properties were evaluated for the neat [Et3NH][TFSA], and the temperature dependence of viscosity and conductivity can be described by the VTF equation. The evolution of conductivity with the addition of acetonitrile rendered it possible to determine the optimal mixture at 25 °C, with a weight fraction of acetonitrile of 0.5. This mixture was also evaluated for transport properties, and showed a Newtonian behavior, as the neat PIL. An electrochemical study demonstrated, at first, a passivation on Al after the second cyclic voltammogram. Subsequently, the electrochemical window was estimated using a three-electrode cell to 4 V on a platinum electrode, and to 2.5 V on activated carbon. Finally, the neat PIL was found to exhibit good performances as promising electrolyte for supercapacitor applications.
119 citations
TL;DR: Preliminary results show that Ni[N(SiMe(3))(DIPP)](2) is a catalyst for the hydrosilation of olefins with secondary silanes at ambient temperature.
93 citations
TL;DR: Inefficient regeneration of the sensitizer appears to be the efficiency-limiting step in the device, and the values presented here will be used to design more efficient dyes, with more cathodic reduction potentials, for photocathodes in tandem dye-sensitized solar cells.
Abstract: A series of perylene dyes with different optical and electronic properties have been used as photosensitizers in NiO-based p-type dye-sensitized solar cells. A key target is to develop dyes that absorb light in the red to near-infrared region of the solar spectrum in order to match photoanodes optically in tandem devices; however, the photocurrent produced was found to decrease dramatically as the absorption maxima of the dye used was varied from 517 to 565 nm and varied strongly with the electrolyte solvent (acetonitrile, propionitrile, or propylene carbonate). To determine the limitations of the energy properties of the dye molecules and to provide guidelines for future sensitizer design, we have determined the redox potentials of the diiodide radical intermediate involved in the charge-transfer reactions in different solvents using photomodulated voltammetry. E°(I3–/I2•–) (V vs Fe(Cp)2+/0) = −0.64 for propylene carbonate, −0.82 for acetonitrile, and −0.87 for propionitrile. Inefficient regeneration of ...
92 citations
TL;DR: In this paper, the molybdenum-oxo complex (MoO) was used to reduce protons at a glassy carbon electrode in acidic organic media, where the active catalyst was shown to be diffusing freely in solution.
Abstract: We recently reported the catalytic generation of hydrogen from water mediated through the in situ reduction of the molybdenum(IV)–oxo complex [(PY5Me2)MoO]2+ (1; PY5Me2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine) at a mercury electrode. To gain further insight into this unique molecular motif for hydrogen production, we have now examined the competence of this complex for the catalytic reduction of protons on an alternative electrode material. Herein, we demonstrate the ability of the molybdenum–oxo complex 1 to reduce protons at a glassy carbon electrode in acidic organic media, where the active catalyst is shown to be diffusing freely in solution. Cyclic and rotating disk voltammetry experiments reveal that three reductive electrochemical processes precede the catalytic generation of hydrogen, which occurs at potentials more negative than −1.25 V vs. SHE. Gas chromatographic analysis of the bulk electrolysis cell headspace confirms that hydrogen is generated at a Faradaic efficiency of 99%. Under pseudo-first order conditions with an acid-to-catalyst ratio of >290, a rate constant of 385 s−1 is calculated for the reduction of acetic acid in acetonitrile. Taken together, these data show that metal–oxo complex 1 is a competent molecular motif for catalytic generation of hydrogen from protons under soluble and diffusion-limited conditions.
79 citations
TL;DR: A series of air-stable, nitrile-ligated (cyclopentadienone)iron dicarbonyl compounds was synthesized and their activities as catalysts in the transfer reduction of acetophenone were explored as mentioned in this paper.
Abstract: A series of air-stable, nitrile-ligated (cyclopentadienone)iron dicarbonyl compounds was synthesized and their activities as catalysts in the transfer reduction of acetophenone were explored. While all were active catalysts, the acetonitrile adduct was chosen for further study and was found to be active in the transfer reduction of aldehydes and ketones and in the Oppenauer-type oxidation of secondary alcohols. The acetonitrile catalyst exhibited activities similar to those of an analogous air-sensitive iron hydride, but unlike the iron hydride it was unreactive in carbonyl reductions using hydrogen gas.
79 citations
TL;DR: In this article, the binding constants of Lawsone (2-hydroxy-1,4-naphthoquinone) were analyzed in both water and acetonitrile.
Abstract: Lawsone (2-hydroxy-1,4-naphthoquinone), the essential component of henna, is used as a sensitive colorimetric and electrochemical sensor for anions such as cyanide, acetate, fluoride and dihydrogen phosphate (DHP) in acetonitrile. These anions cause a color change in Lawsone's solution from yellow to orange-red. Other anions, such as chloride, bromide, iodide, perchlorate, do not show a significant change. Cyanide changes the color of Lawsone in water:acetonitrile (95:5) solution significantly while acetate causes a slight color change. On the other hand, hydrogen sulfate anion fades the yellow color of the solution. Job's plots show a 1:1 host:guest complex in acetonitrile for cyanide, acetate and fluorides and 1:2 for DHP. In water/acetonitrile the stoichiometry is 1:1 for host:anion. The binding constants show strong binding with cyanide and acetate in both solvent systems.
74 citations
TL;DR: The DFT and TDDFT calculation results suggest that the ratiometric and colorimetric sensing behavior of Cou-BT upon its reaction with cyanide was due to the interrupted π-conjugation and blocked ICT progress.
Abstract: A hybrid coumarin–hemicyanine dye, Cou-BT, was developed as a new ratiometric and colorimetric sensor for cyanide with a sensing mechanism via nucleophilic addition of cyanide anion to the benzothiolium group. Cou-BT shows high sensitivity and selectivity for cyanide detection over other common anion species in aqueous acetonitrile solution. The calculated pseudo-first-order rate constant for cyanide anion addition was (2.13 ± 0.08) × 10−2 s−1 at 298 K, and the detection limit was estimated to be 0.64 μM. The DFT and TDDFT calculation results suggest that the ratiometric and colorimetric sensing behavior of Cou-BT upon its reaction with cyanide was due to the interrupted π-conjugation and blocked ICT progress.
TL;DR: The electrocatalytic reduction of protons to H2 by (where in the highly acidic ionic liquid dibutylformamidium bis(trifluoromethanesulfonyl)amide shows a strong dependence on added water).
Abstract: The electrocatalytic reduction of protons to H(2) by [Ni((P(Ph)(2)N(C6H4-hex))(2)(2)]((BF(4))(2) (where P(Ph)(2)N(C6H4-hex)(2) = 1,5-di(4-n-hexylphenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) in the highly acidic ionic liquid dibutylformamidium bis(trifluoromethanesulfonyl)amide shows a strong dependence on added water. A turnover frequency of 43,000-53,000 s(-1) has been measured for hydrogen production at 25 °C when the mole fraction of water (χ(H(2)O)) is 0.72. The same catalyst in acetonitrile with added dimethylformamidium trifluoromethanesulfonate and water has a turnover frequency of 720 s(-1). Thus, the use of an ionic liquid/aqueous solution enhances the observed catalytic rate by more than a factor of 50, compared to a similar acid in a traditional organic solvent. Complexes [Ni((P(Ph)(2)N(C6H4X))(2)(2)]((BF(4))(2) (X = H, OMe,CH(2)P(O)(OEt)(2), Br) are also catalysts in the ionic liquid/water mixture, and the observed catalytic rates correlate with the hydrophobicity of X.
TL;DR: It was concluded low dielectric solvents that were inert to the ITO gave monolayers that were more stable with a higher density of surface bound molecules because higher dielectrics constant solvented and solvent that coordinate with the surface disrupted SAM formation.
Abstract: The preparation of self-assembled monolayers (SAMs) of organophosphonic acids on indium tin oxide (ITO) surfaces from different solvents (triethylamine, ethyl ether, tetrahydofuran (THF), pyridine, acetone, methanol, acetonitrile, dimethyl sulfoxide (DMSO), or water) has been performed with some significant differences observed. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and contact angle measurement demonstrated that the quality of SAMs depends critically on the choice of solvents. Higher density, more stable monolayers were formed from solvents with low dielectric constants and weak interactions with the ITO. It was concluded low dielectric solvents that were inert to the ITO gave monolayers that were more stable with a higher density of surface bound molecules because higher dielectric constant solvents and solvents that coordinate with the surface disrupted SAM formation.
TL;DR: Ionization was greatest in methanol or water for all compounds that elicited a response, thus revealing that enhanced sensitivity and lower limits of detection are achieved with polar protic solvents.
Abstract: A comprehensive study investigated the effect of polar protic (methanol and water) and polar aprotic (acetonitrile and acetone) solvents on the chromatographic separation and negative-ion electrospray (ESI) response of 49 diverse small, acidic molecules. Flow injection experiments on a triple quadrupole were used to measure the response in neat solvents after optimization of source conditions and implementation of a rigorous quality control program (the later ensured that changes in analyte response were due to the analyte/solvent measured and not changes in instrument performance over time). In all solvents, compounds with electron-withdrawing groups and extended conjugation ionized best due to resonance and inductive effects. Ionization was greatest in methanol or water for all compounds that elicited a response, thus revealing that enhanced sensitivity and lower limits of detection are achieved with polar protic solvents. Response in acetone was equal to or slightly lower than response in acetonitrile ...
TL;DR: A series of stable organosuperbases were efficiently synthesized from N,N'-dialkylthioureas and 3-hydroxy-2-butanone and their basicities were measured in acetonitrile and the derivatives with tert-alkyl groups on the imino nitrogen were found to be more basic than the tBuP(1) (pyrr) phosphazene base in aconetitrile.
Abstract: A series of stable organosuperbases, N-alkyl- and N-aryl-1,3-dialkyl-4,5-dimethylimidazol-2-ylidene amines, were efficiently synthesized from N,N'-dialkylthioureas and 3-hydroxy-2-butanone and their basicities were measured in acetonitrile. The derivatives with tert-alkyl groups on the imino nitrogen were found to be more basic than the tBuP(1) (pyrr) phosphazene base in acetonitrile. The origin of the high basicity of these compounds is discussed. In acetonitrile and in the gas phase, the basicity of the alkylimino derivatives depends on the size of the substituent at the imino group, which influences the degree of aromatization of the imidazole ring, as measured by (13)C NMR chemical shifts or by the calculated ΔNICS(1) aromaticity parameters, as well as on solvation effects. If a wider range of imino-substituents, including electron-acceptor substituents, is treated in the analysis then the influence of aromatization is less predominant and the gas-phase basicity becomes more dependent on the field-inductive effect, polarizability, and resonance effects of the substituent.
TL;DR: In this paper, the optimal solvent mixture ratio was determined to improve flexibility while maintaining the thermal expansion stability of PLA film using the solvent casting technique, and the results showed that PLA film produced by solvent casting from solvent mixture compared to a traditional single solvent will have better thermal and mechanical performance.
TL;DR: In this paper, a red-emission diketopyrrolopyrrole (DPP)-based fluoride ion chemosensor (DPP-4 ) with two strong electron-donating triphenylamine groups was designed and synthesized.
Abstract: A new red-emission diketopyrrolopyrrole (DPP)-based fluoride ion chemosensor ( DPP-4 ) with two strong electron-donating triphenylamine groups was designed and synthesized. The sensing properties of DPP-4 for F − were extensively investigated both in acetone and in acetonitrile solutions. Deprotonation of the N–H groups on DPP-4 provided rapid and selective detection of F − in which an apparent color change from red to purple with large red shift in ambient light can be observed by the naked-eye in both two solvents. However, very distinct sensing behaviors were obtained in the fluorescent changes exhibiting solvent-dependent dual mode approaches, i.e. ratiometric and “turn on” modes in acetone and acetonitrile, respectively. In acetone, ratiometric channel was activated upon addition of n-Bu 4 NF, and more than 50 nm red shift from 590 nm to 641 nm was obtained and accompanied with emission color from orange to purple red. In acetonitrile, a “turn on” response with red emission at 631 nm can be easily recognized, and more than 50-fold enhancement were obtained. TD-DFT calculations indicated that DPP-4 performed an intramolecular charge transfer (ICT) process between triphenylamine to DPP core. Interestingly, the reverse charge transfer process from deprotonated DPP core to triphenylamine moieties was obtained after addition of F − , which resulted in red-shift in absorption spectra of the compound. Furthermore, using fluoride and HSO 4 − anions as two chemical inputs and absorption or fluorescence as output, compound DPP-4 was demonstrated to be a parallel double-INH logic gate in acetonitrile solution.
TL;DR: In this article, the Mole fraction equilibrium solubility of nicotinic acid in six solvents (water, ethanol, dimethyl sulfoxide, acetone, acetonitrile and diethyl ether) was determined over the temperature range (283 to 333) K, using the gravimetric method.
TL;DR: A new silicon reagent, difluoro(trimethylsilyl)acetonitrile, was prepared by insertion of diffluorocarbene into silyl cyanide, and served as a good cyanodifluoromethylating reagent toward aldehydes, N-tosylimines,N-alkylimines and enamines under basic or acidic conditions.
Abstract: A new silicon reagent, difluoro(trimethylsilyl)acetonitrile, was prepared by insertion of difluorocarbene into silyl cyanide. The obtained silane served as a good cyanodifluoromethylating reagent toward aldehydes, N-tosylimines, N-alkylimines, and enamines under basic or acidic conditions.
TL;DR: In acetonitrile, the addition of different concentrations of Cu2+ and a fixed amount of F− to a solution of 2 elaborates Cu2- ion concentration dependent NOR, INH and AND Boolean operators with three distinct emission channels at 585, 515 and 400 nm, respectively.
Abstract: Probes 1 and 2 (CH3CN–H2O; 4:1) at pH 7.0 ± 0.1 (10 mM, HEPES) selectively bind with Zn2+ ions and give a new emission band at 490 nm. These can estimate 20 nM Zn2+ ions as the lowest detection limit. The determination of Zn2+ ions by probe 1 is not interfered by the presence of other metal ions viz. Na+, K+, Mg2+, Ca2+, Sr2+, Fe2+, Co2+, Ni2+, Cd2+, Ag+, Hg2+. However, in the case of probe 2 Cu2+ causes only the fluorescence quenching. In acetonitrile, the addition of different concentrations of Cu2+ (2 μM, 5 μM, 10 μM) and a fixed amount of F− (25 μM) to a solution of 2 (0.25 μM, CH3CN) elaborates Cu2+ ion concentration dependent NOR, INH and AND Boolean operators with three distinct emission channels at 585, 515 and 400 nm, respectively.
TL;DR: By application of slightly acidic polar organic mobile phases as preferred elution mode, it is found that certain amounts of aprotic acetonitrile in protic methanol substantially increased enantioselectivity and resolution of amino acids in a structure-dependent manner.
TL;DR: It was found that whilst acetonitrile provided the highest column efficiencies and lowest detection limits of the solvents studied, acetone also performed well and could be used to resolve the same number of analytes as was possible with aconetitrile.
TL;DR: In this paper, the phase behavior of ternary acetonitrile + water + ionic liquid system was predicted using the COSMO-RS method, and it was found that the influence of anions [OAc]− and [Cl]− on the acetitrile+ water mixture is strong, while the cations have fewer effects on the mixture.
Abstract: The phase behavior of the ternary acetonitrile + water + ionic liquid system was predicted using the COSMO-RS method. The effects of different ionic liquids on the separation of acetonitrile + water were discussed. It was found that the influence of anions [OAc]− and [Cl]− on the acetonitrile + water mixture is strong, while the cations have fewer effects on the mixture. The interaction energies and mixing enthalpies of binary acetonitrile + ionic liquid and water + ionic liquid systems were predicted indicating that the interaction energy between molecules is stronger in the water + ionic liquid mixture than in the acetonitrile + ionic liquid system. The excess enthalpies of binary mixtures mainly depend on the hydrogen bonds formed between water (or acetonitrile) and ionic liquids. Ionic liquids [EMIM][OAc] and [EMIM]Cl are expected to be favorable solvents and supposed to have practical applications in the separation of acetonitrile from aqueous solution.
TL;DR: The new bioglycerol-based carbon catalyst acts as an efficient, readily available, and reusable catalyst for the synthesis of 2,4,5-trisubstituted imidazoles/1,2,4-5-tetrasubstitute imidzoles, when aromatic aldehyde, ammonium acetate/amine, and 1,2-diketone are reacted in acetonitrile.
TL;DR: In this article, the effect of the water content in organic solvents on the complex formation of hydrazone dye with acetate ions was utilized for the signalling of water content.
TL;DR: In this article, a family of heterocyclic thiosemicarbazone dyes (3a-f and 4) containing furyl groups was synthesized in good yields, characterized and their response in acetonitrile in the presence of selected anions was studied.
Abstract: A family of heterocyclic thiosemicarbazone dyes (3a–f and 4) containing furyl groups was synthesized in good yields, characterized and their response in acetonitrile in the presence of selected anions was studied. Acetonitrile solutions of 3a–f and 4 showed absorption bands in the 335–396 nm range which are modulated by the electron donor or acceptor strength of the heterocyclic systems appended to the thiosemicarbazone moiety. Fluoride, chloride, bromide, iodide, dihydrogen phosphate, hydrogen sulphate, nitrate, acetate and cyanide anions were used in recognition studies. From these anions, only sensing features were seen for fluoride, cyanide, acetate and dihydrogen phosphate. Two clearly different chromo-fluorogenic behaviours were observed: (i) a small shift of the absorption band due to the coordination of the anions with the thiourea protons and (ii) the appearance of a new red shifted band due to deprotonation. For the latter effect, a change in the colour of solution from pale yellow to purple was observed. Fluorescence studies were also in agreement with the different effects observed in the UV/Vis titrations. In this case, hydrogen bonding interactions were visible through the enhancement of the emission band, whereas deprotonation induced the appearance of a new red-shifted emission. Logarithms of stability constants for the two processes (complex formation + deprotonation) for receptors 3a–f in the presence of fluoride and acetate anions were determined from spectrophotometric titrations using the HypSpec V1.1.18 program. Semi-empirical calculations to evaluate the hydrogen-donating ability of the receptors and a prospective electrochemical characterization of compound 3b in the presence of fluoride were also performed.
TL;DR: The response to ultrafast laser shock loading of nine liquids was monitored in an effort to reveal evidence of chemical changes occurring during the first 350 ps following the shock front, despite the application of shock stress that was in many cases well above the reaction threshold observed at microsecond time scales.
Abstract: The response to ultrafast laser shock loading of nine liquids was monitored in an effort to reveal evidence of chemical changes occurring during the first 350 ps following the shock front. In an effort to compare molecular structures possessing a variety of common bonding patterns, data were acquired for the liquids: cyclohexane, cyclohexene, 1,3-cyclohexadiene, benzene, water, acetonitrile, acrylonitrile, tert-butylacetylene, and phenylacetylene. Transient absorption spectra were measured in the spectral region from 440 to 780 nm over shock stress states from 7 to 20 GPa. Ultrafast dynamic ellipsometry was used to measure the shock and particle velocity as well as the shocked refractive index. Significant transient absorption attributed to chemical reaction was observed for shocked phenylacetylene and acrylonitrile. Evidence of volume decreasing chemical reactions was also observed in the ultrafast dynamic ellipsometry data for phenylacetylene and acrylonitrile. The liquid 1,3-cyclohexadiene exhibited vo...
TL;DR: A convenient and high yield method for oxidation of alcohols directly to carboxylic acids has been developed.
TL;DR: In this paper, the densities of ionic liquids were determined for the binary systems of 1-ethyl-3-methylimidazolium tetrafluoroborate, [Emim][BF4] and 1-hexyl-3methyloride-naphroxymethyl tetraflamide tetrafluoric acid, [Hmim] with the molecular solvents dimethyl sulfoxide (DMSO) and acetonitrile (ACN) at atmospheric pressure over the entire range of composition and temperatures from (298.
Abstract: The densities have been determined for the binary systems of ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate, [Emim][BF4] and 1-hexyl-3-methylimidazolium tetrafluoroborate, [Hmim][BF4], with the molecular solvents dimethyl sulfoxide (DMSO) and acetonitrile (ACN) at atmospheric pressure over the entire range of composition and temperatures from (298.15 to 353.15) K. From experimental densities, the excess molar volumes, VE, were calculated and fitted to a Redlich–Kister equation. Moreover, the VE results have been discussed in terms of the Prigogine–Flory–Patterson (PFP) theory. The VE variation was interpreted in terms of intermolecular interactions and structural effects on mixing.