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Solvent Interactions (solvent + interaction)
Selected AbstractsMethod for predicting solubilities of solids in mixed solventsAICHE JOURNAL, Issue 5 2009Martin E. Ellegaard Abstract A method is presented for predicting solubilities of solid solutes in mixed solvents, based on excess Henry's law constants. The basis is statistical mechanical fluctuation solution theory for composition derivatives of solute/solvent infinite dilution activity coefficients. Suitable approximations are made for a single parameter characterizing solute/solvent interactions. Comparisons with available data show that the method is successful in describing a variety of observed mixed solvent solubility behavior, including nearly ideal systems with small excess solubilities, systems with solute-independent excess solubilities, and systems deviating from these simple rules. Successful predictions for new solvent mixtures can be made using limited data from other mixtures. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Effect of hydrophobic side-chains on the solvation of imidazolium saltsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 10 2005Allan D. Headley Abstract The chemical shifts of the aromatic hydrogens of 12 symmetrical imidazolium salts were determined in different deuterated solvents. Based on the magnitude of the chemical shift change for the hydrogens of the imidazolium ion in the various solvents, relationships were developed to determine the relative solute/solvent interactions for these compounds. Owing to different degrees of interactions involving the aromatic hydrogens of the imidazolium cations and anions, there is a variation in the interaction of the hydrogens with the solvent molecules. The intimate interaction that exists between the hydrogens of the imidazolium cation and the BF anion results in the BF salts being less solvated compared with salts containing BF and SbF anions. For imidazolium salts that contain C2H5, C4H9 and C8H17 side-chains bonded in the 1 and 3 positions, the interaction between H2 and the solvents was observed to be greater than for imidazolium salts with C16H33 substituents. On the other hand, for imidazolium salts that have C16H33 substituents the interaction between H2 and the solvents is similar to that for H4 and H5. Copyright © 2005 John Wiley & Sons, Ltd. [source] Synthesis and Chemical Properties of Diacetylenes with Pyridinium and 4,4,-Bipyridinium GroupsHELVETICA CHIMICA ACTA, Issue 5 2010Isao Yamaguchi Abstract Diacetylenes (DAs) having a dipolar D- , -A structure (D=donor: amino group; ,=, -conjugation core; A=acceptor: pyridinium (Py) and bipyridinium (BPy) groups), i.e., 4 (APBPyDA) and 5 (APPyPyDA), or an A- , -A structure, i.e., 7 (DBPyDA) and 8 (PyDA(Cl)), were obtained by 1,:,1 and 1,:,2 reactions of 4,4,-(buta-1,3-diyne-1,4-diyl)bis[benzenamine] (APDA; 3) with 1-(2,4-dinitrophenyl)-1,-hexyl-4,4,-bipyridinium bromide chloride (1,:,1,:,1) (1), 1-(2,4-dinitrophenyl)-4-(pyridin-4-yl)pyridinium chloride (2), or 1-(2,4-dinitrophenyl)pyridinium chloride (6) (Schemes 1 and 2). The anion-exchange reactions of 8 with NaI and Li(TCNQ) (TCNQ,=2,2,-(cyclohexa-2,5-diene-1,4-diylidene)bis[propanedinitrile] radical ion (1,)) yielded the corresponding I, and TCNQ, salts 9 (PyDA(I)) and 10 (PyDA(TCNQ)). Compounds 10 and 4 exhibited a UV/VIS absorption due to a charge transfer between the TCNQ, and the pyridinium groups and a strong solute,solvent interaction of a dipolar solute molecule in the polar environment, respectively. Compounds 8,10 exhibited photoluminescence in solution, whereas 4 and 7 did not because of the presence of the 4,4,-bipyridinium quenching groups. Differential-scanning-calorimetry (DSC) measurements suggested that the DAs obtained in this study can be converted into poly(diacetylenes) by thermal polymerization. [source] Effect of solvent and structure on the kinetics and mechanism of the aquation of bromopentaamine cobalt(III) complex in binary aqueous mixturesINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2004Gehan M. El-Subruiti The kinetics of aquation of bromopentaamine cobalt(III) complex have been investigated spectrophotometrically in aqueous-organic solvent media using acetonitrile, urea, and dimethyl sulfoxide as co-solvents at 45 , T (°C) , 65. The logarithms of rate constant of the aquation reaction vary nonlinearly with the reciprocal of the dielectric constant for all cosolvent mixtures, indicating a specific solute,solvent interaction. Also, the rate constants are correlated with the total number of moles of water and the organic solvents. However, the solvent effects on the solvation components of the enthalpy of activation, ,H,, and the entropy of activation, ,S,, have been studied. Analysis of the solvent effect confirmed a common Id mechanism for the aquation of the cobalt(III) complex. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:494,499, 2004 [source] Concentration dependent Raman and IR study on salicylaldehyde in binary mixturesJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2007A. Anis Fathima Abstract A vibrational spectroscopic study of binary mixtures of salicylaldehyde (SA) in three different solvents (polar and nonpolar) is presented. The vibrational modes ,(CO), hydroxyl stretching mode (COH) and aldehydic (CH) stretching vibration were analyzed. Changes in wavenumber position and full width half maximum have been explained for neat as well as binary mixtures with different volume fractions of the reference system, SA, in terms of inter- and intramolecular hydrogen bonding. The IR spectra of these mixtures have also been taken and compared with the Raman data. The spectral changes have been well explained using the concentration fluctuation model and solute,solvent interaction. Copyright © 2007 John Wiley & Sons, Ltd. [source] Changes in spectral features with varying mole fractions of anisaldehyde in binary mixturesJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2007A. Anis Fathima Abstract Raman and IR spectra of neat anisaldehyde (4-methoxybenzaldehyde (4MeOBz)) and its binary mixtures (in polar and nonpolar solvents) with varying mole fraction of 4MeOBz were investigated. The concentration dependence of the wavenumber position and line width (full width at half maximum, FWHM) was analyzed to study the interaction of the solute vibrational modes with the microscopic solvent environment. The wavenumbers of Raman modes of 4MeOBz, namely, the carbonyl stretching, aldehydic , (CH) and ring-breathing modes, showed a linear variation in the peak position for varying concentrations of 4MeOBz in the different solvents. The dependence of Raman line width with concentration of 4MeOBz of these modes was also taken into account. The solute,solvent interaction is stronger in 2-propanol and acetonitrile because of the formation of hydrogen bonds between them, whereas in benzene the interaction is too weak to affect the Raman modes. The modes, , (CO) in 2-propanol and aldehydic , (CH) in acetonitrile, gave a Gaussian-type line width variation, which was explained by the concentration fluctuation model, and the linear variation of the line widths was also interpreted by solute,solvent interactions. IR spectra were taken for these binary mixtures, which also give further support to these data. Copyright © 2006 John Wiley & Sons, Ltd. [source] Solvent hydrogen bonding and structural effects on nucleophilic substitution reactions: Part 3.INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 12 2007Reaction of benzenesulfonyl chloride with anilines in benzene/propan-2-ol mixtures Substitution reactions of 13 para- and meta-substituted anilines with benzenesulfonyl chloride in varying mole fractions of benzene in propan-2-ol have been investigated conductometrically. The second-order rate constants correlate well with pKa values of anilines and with the Hammett's equation. The negative Hammett reaction constant indicates the formation of an electron-deficient transition state. The rate data correlate satisfactorily with macroscopic solvent parameters such as relative permittivity, ,r, and polarity, ETN. Correlation of rate data with Kamlet,Taft solvatochromic parameters (,, ,, ,*) suggests that both the specific and nonspecific solute,solvent interactions influence the reactivity. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 657,663, 2007 [source] Studies on the kinetics of imidazolium fluorochromate oxidation of some meta - and para -substituted anilines in nonaqueous mediaINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 3 2006D. S. Bhuvaneshwari The imidazolium fluorochromate (IFC) oxidation of meta - and para -substituted anilines, in seven organic solvents, in the presence of p -toluenesulfonic acid (TsOH) is first order in IFC and TsOH and is zero order with respect to substrate. The IFC oxidation of 15 meta - and para -substituted anilines at 299,322 K complies with the isokinetic relationship but not to any of the linear free energy relationships; the isokinetic temperature lies within the experimental range. The specific rate of oxidizing species-anilines reaction (k2) correlates with substituent constants affording negative reaction constants. The rate data failed to correlate with macroscopic solvent parameters such as ,r and ENT. A correlation of rate data with Kamlet,Taft solvatochromic parameters (,, ,, ,*) suggests that the specific solute,solvent interactions play a major role in governing the reactivity, and the observed solvent effects have been explained on the basis of solute,solvent complexation. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 166,175, 2006 [source] Nonempirical calculations of nonlinear optical properties of p -nitroaniline in acetone: Comparison of supermolecule and semicontinuum approachesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2007Marina Yu. Abstract The comparison of the conventional continuum, supermolecule, and semicontinuum models for the description of solvent effect on the (hyper)polarizability of p -nitroaniline (PNA) in acetone is performed. The supermolecule approach is used for the clusters containing PNA and one or two acetone molecules. The account of the specific solute,solvent interactions via the hydrogen bonds formation is shown to result in the enhancement of (hyper)polarizability values. The continuum approach exploited in the framework of polarizable continuum model (PCM) was shown to describe mainly the solvent effect on (hyper)polarizability. The semicontinuum approach, accounting explicitly the interaction between PNA and solvent molecules and treating the rest of the solvent as a continuum, results in a moderate increase of the (hyper)polarizability values compared to those obtained within the conventional PCM approach. All the calculations of (hyper)polarizabilities are performed at the Hartree,Fock level in the aug-cc-pVDZ' Dunning basis set. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] QM/MM calculation of solvent effects on absorption spectra of guanineJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 1 2010Maja Parac Abstract Electronic spectra of guanine in the gas phase and in water were studied by quantum mechanical/molecular mechanical (QM/MM) methods. Geometries for the excited-state calculations were extracted from ground-state molecular dynamics (MD) simulations using the self-consistent-charge density functional tight binding (SCC-DFTB) method for the QM region and the TIP3P force field for the water environment. Theoretical absorption spectra were generated from excitation energies and oscillator strengths calculated for 50 to 500 MD snapshots of guanine in the gas phase (QM) and in solution (QM/MM). The excited-state calculations used time-dependent density functional theory (TDDFT) and the DFT-based multireference configuration interaction (DFT/MRCI) method of Grimme and Waletzke, in combination with two basis sets. Our investigation covered keto-N7H and keto-N9H guanine, with particular focus on solvent effects in the low-energy spectrum of the keto-N9H tautomer. When compared with the vertical excitation energies of gas-phase guanine at the optimized DFT (B3LYP/TZVP) geometry, the maxima in the computed solution spectra are shifted by several tenths of an eV. Three effects contribute: the use of SCC-DFTB-based rather than B3LYP-based geometries in the MD snapshots (red shift of ca. 0.1 eV), explicit inclusion of nuclear motion through the MD snapshots (red shift of ca. 0.1 eV), and intrinsic solvent effects (differences in the absorption maxima in the computed gas-phase and solution spectra, typically ca. 0.1,0.3 eV). A detailed analysis of the results indicates that the intrinsic solvent effects arise both from solvent-induced structural changes and from electrostatic solute,solvent interactions, the latter being dominant. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 [source] Combining a polarizable force-field and a coarse-grained polarizable solvent model: Application to long dynamics simulations of bovine pancreatic trypsin inhibitorJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 11 2008Michel Masella Abstract The dynamic coupling between a polarizable protein force field and a particle-based implicit solvent model is described. The polarizable force field, TCPEp, developed recently to simulate protein systems, is characterized by a reduced number of polarizable sites, with a substantial gain in efficiency for an equal chemical accuracy. The Polarizable Pseudo-Particle (PPP) solvent model represents the macroscopic solvent polarization by induced dipoles placed on mobile Lennard-Jones pseudo-particles. The solvent-induced dipoles are sensitive to the solute electric field, but not to each other, so that the computational cost of solvent,solvent interactions is basically negligible. The solute and solvent induced dipoles are determined self-consistently and the equations of motion are solved using an efficient iterative multiple time step procedure. The solvation cost with respect to vacuum simulations is shown to decrease with solute size: the estimated multiplicative factor is 2.5 for a protein containing about 1000 atoms, and as low as 1.15 for 8000 atoms. The model is tested for six 20 ns molecular dynamics trajectories of a traditional benchmark system: the hydrated Bovine Pancreatic Trypsin Inhibitor (BPTI). Even though the TCPEp parameters have not been refined to be used with the solvent PPP model, we observe a good conservation of the BPTI structure along the trajectories. Moreover, our approach is able to provide a description of the protein solvation thermodynamic at the same accuracy as the standard Poisson-Boltzman continuum methods. It provides in addition a good description of the microscopic structural aspects concerning the solute/solvent interaction. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] Probing the solvation shell of organic molecules by intermolecular 1H NOESY,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 12 2002Alessandro Bagno Abstract The solvation of some neutral and charged organic molecules (phenol, nitroanilines, tetraalkylammonium) in binary solvent mixtures was investigated by means of intermolecular 1H-NOESY NMR spectroscopy. The solvation shell of the solute is, in most cases, selectively enriched in one of the cosolvents (preferential solvation). The origin of preferential solvation is discussed in terms of solute,solvent interactions and microheterogeneity in the solvent mixture. Copyright © 2002 John Wiley & Sons, Ltd. [source] Structural characterization of the ternary solvent mixture methanol,acetonitrile,1-propanol,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 9 2002Ruben Elvas Leitão Abstract Refractive indices and ET values were measured for the ternary mixture methanol,acetonitrile,1-propanol at 25.0,°C for 13 mole fractions, and also for the corresponding binary mixtures, methanol,1-propanol, methanol,acetonitrile and 1-propanol,acetonitrile, at 25.0 and 50.0,°C, at 10 different compositions. Solvent exchange equilibrium models were applied to the transition energy of the Dimroth,Reichardt ET(30) solvatochromic indicator in the binary systems and the Redlich,Kister polynomial was used to correlate excess ETN and nD values for the binary solvent mixtures data. The results allowed the analysis of synergetic behaviours, polarizability effects and preferential solvation trends both in the binary and in the ternary mixtures. Our results point towards the prevalence of specific solute,solvent,solvent interactions mainly due to hydrogen bonding by the hydroxylic components of the ternary mixture. Copyright © 2002 John Wiley & Sons, Ltd. [source] Changes in spectral features with varying mole fractions of anisaldehyde in binary mixturesJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2007A. Anis Fathima Abstract Raman and IR spectra of neat anisaldehyde (4-methoxybenzaldehyde (4MeOBz)) and its binary mixtures (in polar and nonpolar solvents) with varying mole fraction of 4MeOBz were investigated. The concentration dependence of the wavenumber position and line width (full width at half maximum, FWHM) was analyzed to study the interaction of the solute vibrational modes with the microscopic solvent environment. The wavenumbers of Raman modes of 4MeOBz, namely, the carbonyl stretching, aldehydic , (CH) and ring-breathing modes, showed a linear variation in the peak position for varying concentrations of 4MeOBz in the different solvents. The dependence of Raman line width with concentration of 4MeOBz of these modes was also taken into account. The solute,solvent interaction is stronger in 2-propanol and acetonitrile because of the formation of hydrogen bonds between them, whereas in benzene the interaction is too weak to affect the Raman modes. The modes, , (CO) in 2-propanol and aldehydic , (CH) in acetonitrile, gave a Gaussian-type line width variation, which was explained by the concentration fluctuation model, and the linear variation of the line widths was also interpreted by solute,solvent interactions. IR spectra were taken for these binary mixtures, which also give further support to these data. Copyright © 2006 John Wiley & Sons, Ltd. [source] So how do you know you have a macromolecular complex?ACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2007Timothy R. Dafforn Protein in crystal form is at an extremely high concentration and yet retains the complex secondary structure that defines an active protein. The protein crystal itself is made up of a repeating lattice of protein,protein and protein,solvent interactions. The problem that confronts any crystallographer is to identify those interactions that represent physiological interactions and those that do not. This review explores the tools that are available to provide such information using the original crystal liquor as a sample. The review is aimed at postgraduate and postdoctoral researchers who may well be coming up against this problem for the first time. Techniques are discussed that will provide information on the stoichiometry of complexes as well as low-resolution information on complex structure. Together, these data will help to identify the physiological complex. [source] Urea interactions with protein groups: A volumetric study,BIOPOLYMERS, Issue 10 2010Soyoung Lee Abstract We determined the partial molar volumes and adiabatic compressibilities of N -acetyl amino acid amides, N -acetyl amino acid methylamides, N -acetyl amino acids, and short oligoglycines as a function of urea concentration. We analyze these data within the framework of a statistical thermodynamic formalism to determine the association constants for the reaction in which urea binds to the glycyl unit and each of the naturally occurring amino acid side chains replacing two waters of hydration. Our determined association constants, k, range from 0.04 to 0.39M. We derive a general equation that links k with changes in free energy, ,Gtr, accompanying the transfer of functional groups from water to urea. In this equation, ,Gtr is the sum of a change in the free energy of cavity formation, ,,GC, and the differential free energy of solute,solvent interactions, ,,GI, in urea and water. The observed range of affinity coefficients, k, corresponds to the values of ,,GI ranging from highly favorable to slightly unfavorable. Taken together, our data support a direct interaction model in which urea denatures a protein by concerted action via favorable interactions with a wide range of protein groups. Our derived equation linking k to ,Gtr suggests that ,,GI and, hence, the net transfer free energy, ,Gtr, are both strongly influenced by the concentration of a solute used in the experiment. We emphasize the need to exercise caution when two solutes differing in solubility are compared to determine the ,Gtr contribution of a particular functional group. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 866,879, 2010. [source] Ionic Liquids Made with Dimethyl Carbonate: Solvents as well as Boosted Basic Catalysts for the Michael ReactionCHEMISTRY - A EUROPEAN JOURNAL, Issue 45 2009Massimo Fabris Dr. Abstract This article describes 1),a methodology for the green synthesis of a class of methylammonium and methylphosphonium ionic liquids (ILs), 2),how to tune their acid,base properties by anion exchange, 3),complete neat-phase NMR spectroscopic characterisation of these materials and 4),their application as active organocatalysts for base-promoted carbon,carbon bond-forming reactions. Methylation of tertiary amines or phosphines with dimethyl carbonate leads to the formation of the halogen-free methyl-onium methyl carbonate salts, and these can be easily anion-exchanged to yield a range of derivatives with different melting points, solubility, acid,base properties, stability and viscosity. Treatment with water, in particular, yields bicarbonate-exchanged liquid onium salts. These proved strongly basic, enough to efficiently catalyse the Michael reaction; experiments suggest that in these systems the bicarbonate basicity is boosted by two orders of magnitude with respect to inorganic bicarbonate salts. These basic ionic liquids used in catalytic amounts are better even than traditional strong organic bases. The present work also introduces neat NMR spectroscopy of the ionic liquids as a probe for solute,solvent interactions as well as a tool for characterisation. Our studies show that high catalytic efficacy of functional ionic liquids can be achieved by integrating their green synthesis, along with a fine-tuning of their structure. Demonstrating that ionic liquid solvents can be made by a truly green procedure, and that their properties and reactivity can be tailored to the point of bridging the gap between their use as solvents and as catalysts. [source] Solvent Effect on Optical Rotation: A Case Study of Methyloxirane in WaterCHEMPHYSCHEM, Issue 12 2006Parag Mukhopadhyay Explicit solute,solvent interactions: MD simulations and TD-DFT are used to determine the solvent dependence of the optical rotatory dispersion (ORD) for methyloxirane in water (see figure). The inclusion of explicit solute,solvent interactions is essential to describe the influence of the solvent on the OR of the system and the MD simulations provide a suitable means to analyze and predict chiroptical solvation effects. [source] The Presence of Functional Groups Key for Biodegradation in Ionic Liquids: Effect on Gas SolubilityCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 3 2010Yun Deng Abstract The effect of the incorporation of either ester or ester and ether functions into the side chain of an 1-alkyl-3-methylimidazolium cation on the physico-chemical properties of ionic liquids containing bis(trifluoromethylsulfonyl)imide or octylsulfate anions is studied. It is believed that the introduction of an ester function into the cation of the ionic liquids greatly increases their biodegradability. The density of three such ionic liquids is measured as a function of temperature, and the solubility of four gases,carbon dioxide, ethane, methane, and hydrogen,is determined between 303,K and 343,K and at pressures close to atmospheric level. Carbon dioxide is the most soluble gas, followed by ethane and methane; the mole fraction solubilities vary from 1.8×10,3 to 3.7×10,2. These solubilities are of the same order of magnitude as those determined for alkylimidazolium-based ionic liquids. The chemical modification of the alkyl side chain does not result in a significant change of the solvation properties of the ionic liquid. All of the solubilities decrease with increasing temperature, corresponding to an exothermal solvation process. From the variation of this property with temperature, the thermodynamic functions of solvation (Gibbs energy, enthalpy, and entropy) are calculated and provide information about the solute,solvent interactions and the molecular structure of the solutions. [source] The effects of conformation and solvation on optical rotation: Substituted epoxides,CHIRALITY, Issue 3-4 2008Shaun M. Wilson Abstract The vapor-phase optical rotation (or circular birefringence) of (S)-1,2-epoxybutane, (S)-epichlorohydrin, and (S)-epifluorohydrin has been measured at the nonresonant excitation wavelengths of 355 nm and 633 nm by means of Cavity Ring-Down Polarimetry (CRDP). Complementary solution-phase studies were performed in a wide variety of dilute solvent media to highlight the pronounced influence of solute,solvent interactions. Density functional theory calculations of optical activity have been enlisted to unravel the structural and electronic provenance of experimental observations. Three stable, low-lying conformers have been identified and characterized for each of the targeted chiral species, with thermal (relative population weighted) averaging of their antagonistic chiroptical properties allowing specific rotation values to be predicted under both isolated and solvated conditions. For (S)-epichlorohydrin and (S)-epifluorohydrin, a self-consistent isodensity polarizable continuum model (SCI-PCM) has been exploited to gain further insight into the underlying nature of solvation effects. Chirality, 2008. © 2007 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||