Kirkwood Correlation Factor Research Articles

Thermodynamics of amide + amine mixtures. 4. Relative permittivities of N,N-dimethylacetamide + N-propylpropan-1-amine, + N-butylbutan-1-amine, + butan-1-amine, or + hexan-1-amine systems and of N,N-dimethylformamide + aniline mixture at several temperatures. Characterization of amine + amide systems using ERAS

Relative permittivities at 1 MHz, εr, and at (293.15–303.15) K are reported for the binary systems N,N-dimethylacetamide (DMA) + N-propylpropan-1-amine (DPA), + N-butylbutan-1-amine (DBA), + butan-1-amine (BA) or + hexan-1-amine (HxA) and for N,N-dimethylformamide (DMF) + aniline. The excess permittivities, εrE, are large and negative for systems with DMA, whereas they are large and positive for the aniline mixture. From the analysis of these εrE data and of measurements previously reported, it is concluded: (i) the main contribution to εrE in systems with linear amines arises from the breaking of interactions between like molecules; (ii) in the DMF + aniline mixture, interactions between unlike molecules contribute positively to εrE, and such a contribution is dominant; (iii) longer linear amines are better breakers of the amide-amide interactions; (iv) interactions between unlike molecules are more easily formed when shorter linear amines, or DMF, participate. These findings are confirmed by a general study conducted in terms of excess values of molar orientational and induced polarizabilities and of the relative Kirkwood correlation factors for systems and components. The ERAS model is also applied to amide + amine mixtures. ERAS represents rather accurately the excess enthalpies and volumes of the mentioned systems. The variation of the cross-association equilibrium constants, determined using ERAS, with the molecular structure is in agreement with that observed for εrE.

Modifying hydrogen-bonded structures by physical vapor deposition: 4-methyl-3-heptanol.

We prepared films of 4-methyl-3-heptanol by vapor depositing onto substrates held at temperatures between Tdep = 0.6Tg and Tg, where Tg is the glass transition temperature. Using deposition rates between 0.9 and 6.0 nm/s, we prepared films about 5 μm thick and measured the dielectric properties via an interdigitated electrode cell onto which films were deposited. Samples prepared at Tdep = Tg display the dielectric behavior of the ordinary supercooled liquid. Films deposited at lower deposition temperatures show a high dielectric loss upon heating toward Tg, which decreases by a factor of about 12 by annealing at Tg = 162 K. This change is consistent with either a drop of the Kirkwood correlation factor, gk, by a factor of about 10, or an increase in the dielectric relaxation times, both being indicative of changes toward ring-like hydrogen-bonded structure characteristic of the ordinary liquid. We rationalize the high dielectric relaxation amplitude in the vapor deposited glass by suggesting that depositions at low temperature provide insufficient time for molecules to form ring-like supramolecular structures for which dipole moments cancel. Surprisingly, above Tg of the ordinary liquid, these vapor deposited films fail to completely recover the dielectric properties of the liquid obtained by supercooling. Instead, the dielectric relaxation remains slower and its amplitude much higher than that of the equilibrium liquid state, indicative of a structure that differs from the equilibrium liquid up to at least Tg + 40 K.

Conformational and dielectric relaxation studies on hydrogen bonded binary mixture of ethyl acetate in 1-butanol and 1-pentanol

ABSTRACTThe dielectric relaxation study for the hydrogen bonded binary system of polar liquid ethyl acetate in 1-butanol and 1-pentanol, has been carried out at 11 concentrations over the frequency range of 10 MHz to 20 GHz at 30°C using TDR. The least squares fit method has been used to obtain the static dielectric constant (ϵ0) and relaxation time (τ). By using dielectric parameters the excess permittivity (ϵE), excess inverses relaxation time (1/τ)E, Kirkwood Correlation factor (g) are also obtained to explore the hydrogen-bonded hetero-molecular interactions. Conformational analysis of the hydrogen bond between the two systems is supported by the FTIR spectra.

Dielectric characterization and molecular interaction behavior in amide–amide binary mixture

ABSTRACTThe frequency dependent dielectric relaxation spectra for binary mixture of dimethylacetamide with formamide and dimethylformamide at 11 different concentrations at 30°C over frequency range 10 MHz to 20 GHz is studied. The mixture exhibit a principle dispersion of the Davidson-Cole relaxation type. Dielectric constant (ϵ0), relaxation time (τ), excess dielectric constant (ϵE), excess inverse relaxation time (1/τ)E and Kirkwood correlation factor (g) have been determined and discussed in terms of the effect of NH2 and –CH3 side group on molecular dynamics and intermolecular hydrogen bonds. Conformational analysis of the formation of hydrogen bond is supported by the FTIR study.

Investigation of intermolecular interactions between amide-amine binary mixtures through dielectric relaxation study

ABSTRACTDielectric relaxation study on dimethylacetamide with ethanolamine and dimethylaminoethanol binary mixtures has been carried out at eleven concentrations over the frequency range of 10 MHz to 20 GHz at 30°C using TDR technique. The least squares fit method has been used to obtain the static dielectric constant (ϵ0) and relaxation time (τ). By using these dielectric parameters, the excess permittivity (ϵE), excess inverse relaxation time (1/τ)E and Kirkwood correlation factor (geff) are also obtained for investigating the intermolecular interaction. Conformational analysis of the intermolecular interaction between DMA-ETA and DMA-DMAE systems is supported by the FTIR spectra.

Dielectric and FTIR studies on the hydrogen bonded binary system of ester and alcohol

ABSTRACTConcentration dependent dielectric constant, relaxation time, excess dielectric constant, excess inverse relaxation time and the effective Kirkwood correlation factor of the binary mixture of methyl acetate with butanol and pentanol, over the entire mixing range have been determined at room temperature. The values of these functions emphasize on the hydrogen bond interactions between the unlike molecules in ester-alcohols mixtures, the nature of which depends on the extent of substitution of the alcohols. The concentration depending values of excess dielectric constant and excess inverses relaxation time were used to analyze the hydrogen bonding complexes formed between unlike molecules and the strength of the molecular connectivities in the binary mixtures. Conformational analysis of the formation of hydrogen bond is also supported by the FTIR study.

Dielectric studies of binary mixtures of ethylene glycol mono phenyl ether with 1-butanol at different temperatures

Static permittivity ([Formula: see text]), refractive index ([Formula: see text]) and density ([Formula: see text]) of binary mixtures of ethylene glycol mono phenyl ether (EGMPE) with 1-butanol (1-BuOH) over the entire range of mole fraction and at temperatures ([Formula: see text], 313.15 and 323.15[Formula: see text]K) have been measured. From the experimental data, parameters such as excess static permittivity ([Formula: see text]), excess permittivity at optical frequency ([Formula: see text]), effective Kirkwood correlation factor ([Formula: see text]), corrective Kirkwood correlation factor ([Formula: see text]) and Bruggeman factor ([Formula: see text]) have been calculated to obtain qualitative and quantitative information about the complex formation through H-bond in binary system. In order to predict the static permittivity of polar–polar binary mixtures six mixing rules were applied and for refractive index five mixing rule were applied. Experimental results of permittivity ([Formula: see text]) and refractive index (n) are compared with those obtained from theoretical calculations. Excess parameters were fitted to the Redlich–Kister type polynomial equation.

Physico-chemical and dielectric relaxation studies of ionic surfactants in Time Domain Reflectometry (TDR)

The properties of aqueous surfactant solutions with external additives are extensively useful in surfactant-based systems. To study the dielectric relaxation studies of aqueous ionic surfactants (SDS, CTAB, DPC) and aqueous butanol, benzyl alcohol, aniline and tributylamine were carried out for different concentrations at 303k. Dielectric relaxation spectroscopy (DRS) is valuable for understanding the dynamic process mainly in micellar systems. Time domain dielectric data were obtained through HP54750A oscilloscope and TDR plug-in-module. The relaxation times were determined through the well-known Cole-Cole method. The superposition of two relaxation times gives the dielectric relaxation time obtained from the hydrated water molecule with rotations around the micelle, ions and another hydrophobic inner side of the micelle. Viscosity measurements were used to correlate the dielectric data. The Kirkwood correlation factor (g f ), effective Kirkwood correlation factor (g eff ), Bruggeman Factor (f B ), excess inverse relaxation time (1/τ) E , excess dielectric constant (e E ) and free energy of activation (ΔF t ) were also calculated. The effects of dielectric relaxation and viscous flow were interpreted and discussed.

Dielectric relaxation study of amides with alcohol mixtures by time domain reflectometry

Using Time Domain Reflectometry (TDR), dielectric relaxation studies have been carried out on binary mixtures of amides (N-methylacetamide, N,N-dimethylacetamide) with alcohol (1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol and 1-decanol) for various concentrations over the frequency range from 10 MHz to 10 GHz at 303 K. The Kirkwood correlation factor and excess dielectric constant properties were determined and discussed to yield information on the molecular interactions of the systems. The relaxation time is varies with the chain length of alcohols and substituted amides are observed. The Bruggeman plot shows a deviation from linearity. This deviation was attributed to some sort of molecular interaction which might place between the alcohols and substituted amides. The excess static permittivity and excess inverse relaxation time values vary from negative to positive for all the systems indicating the solute-solvent interaction to exist between alcohol and substituted amides for all the dynamics of the mixture.

Dielectric study of H-bonded interactions in amyl alcohols with ketones and DMSO at T = 298.15 K

This paper reports the role of hydrogen bonding and other electrostatic interactions on the dielectric behaviour, excess parameters, and structure properties of the binary systems containing 1-pentanol isomers (H-bond donors) and dipolar aprotic liquids at T=298.15K. The dipolar aprotic liquids were four H-bond acceptor, i.e. dimethyl ketone (acetone), methyl ethyl ketone (2-butanone), methyl phenyl ketone (acetophenone), and dimethyl sulfoxide (DMSO). In order to make a coherent discussion, the dielectric data were analyzed with various approaches in terms of intermolecular interactions between like and unlike molecules. In order to obtain valuable information about hetero interaction and structure occurring in the studied systems, the effective and corrective Kirkwood correlation factors were calculated using Kumbharkhane et al. approach. The Winkelmann-Quitzsch theory was employed to obtain excess Helmholtz energies of dipole-dipole interactions. The Reis and Iglesias approach was applied to calculate excess Kirkwood correlation factors.

Thermodynamics of amide + amine mixtures. 3. Relative permittivities of N,N-dimethylformamide + N-propylpropan-1-amine, + N-butylbutan-1-amine, + butan-1-amine, or + hexan-1-amine systems at several temperatures

Relative permittivities at 1MHz, εr, and at (293.15–303.15)K, are reported for the binary systems N,N-dimethylformamide (DMF)+N-propylpropan-1-amine (DPA), +N-butylbutan-1-amine (DBA), +butan-1-amine (BA) or +hexan-1-amine (HxA). The values of the excess relative permittivities, εrE, have also been determined for these solutions. The measurements were realized by means of a precision impedance analyser 4294A, to which a 16452A cell connected using a 16048G test lead, all of them from Agilent. The εrE values are large and negative, and diminish when the size of the amine increases along a homologous series, which has been ascribed mainly to the rupture of interactions between like molecules along mixing. Calculations on excess molar orientational polarizabilities support this conclusion, indicating a dominant contribution to εrE from the orientational polarizability of the molecules in the mixture. The analysis of excess relative Kirkwood correlation factors shows that the correlation between dipoles is effectively decreased along the mixing process.

Investigation on molecular interaction studies of binary mixture of DEHPA and petrofin at 298.15 K

ABSTRACTThe present article reports the values of density (ρ12), molar volume (V12), apparent molar volume (Vɸ), dielectric constant (ϵ12), molar polarisation (P12) and molar refraction (R12) of binary mixture of di-2-ethylhexyl phosphoric acid (DEHPA) and petrofin at various compositions. The excess properties such as VE, ϵE, ΔnD, PE and RE have been calculated to throw light on the existence of interaction between the DEHPA and petrofin molecules in the binary mixture. The values of VE and RE were found to be positive while the values of ϵE, ΔnD and PE were negative over the entire composition showing weak interaction between the two unlike molecules in the mixture. The Kirkwood-correlation factors (g) have been evaluated to know the nature of interaction prevailing in DEHPA and petrofin. These data provide useful information regarding interaction between self-associated protic DEHPA and non-associated petrofin which in turn helps the metallurgist to use DEHPA diluted with petrofin as effective solvent in extraction of metals.

Dielectric relaxation and thermodynamic study of polyhydric sugar alcohols in DMSO using TDR technique

The measurement of complex permittivity spectra of binary mixtures of sugar alcohols with DMSO were carried out using picosecond time domain technique at the temperatures ranging from 283.15K to 298.15K. In order to obtain the dielectric parameters, the measured complex permittivity spectra were fitted to the Cole-Davidson model. These dielectric parameters are further used to evaluate the Kirkwood correlation factor and thermodynamic parameters to discuss hydrogen bond formation.

Microwave dielectric relaxation spectroscopy study of propylene glycol/ethanol binary mixtures: Temperature dependence

Complex dielectric permittivity measurements of propylene glycol (PG) in ethanol at various mole fractions were measured by using open-ended coaxial probe technique at different temperatures in the frequency range 0.02<ν/GHz<20. The dipole moment (μ), excess dipole moment (Δμ),excess permittivity (εE), excess inverse relaxation time(1/τ)E, Bruggeman parameter (fB), excess Helmholtz energy (ΔFE) are determined using experimental data. From the minimum energy based geometry optimization, dipole moments of individual monomers of propylene glycol and ethanol and their binary system have been evaluated theoretically at gaseous state as well as alcoholic medium by using PCM and IEFPCM solvation models from the Hatree-Fock (HF) and Density Functional Theory (DFT-B3LYP) methods with 6-311G* and 6-311G** basis sets. The obtained results have been interpreted in terms of the short and long range ordering of the dipoles, Kirkwood correlation factor (geff), thermodynamic parameters, mean molecular polarizability (αM) and interaction in the mixture through hydrogen bonding.

Dielectric study of primary alkanediols (C 3 , C 4 , C 5 ) with 1-pentanol isomers

Relative permittivities and refractive indices were measured for the several polar binary systems containing straight-chain primary diols and primary pentanol isomers over the whole composition range at 298.15 K and atmospheric pressure. The pentanol isomers were 1-pentanol (amyl alcohol), 3-methyl-1-butanol (isoamyl alcohol), and 2-methyl-1-butanol (active amyl alcohol). The chosen diols were 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol. The excess parameters, i.e. excess permittivity, excess Helmholtz energy and excess Kirkwood correlation factor, were determined. The Reis-Ιglesias formulation was used to obtain information on the molecular interactions and structure in these binary systems.

Dielectric properties of benzylamine in 1,2,6-hexanetriol mixture using time domain reflectometry technique

The dielectric properties of binary mixtures of benzylamine-1,2,6-hexantriol mixtures at different volume fractions of 1,2,6-hexanetriol have been measured using Time Domain Reflectometry (TDR) technique in the frequency range of 10 MHz to 30 GHz. Complex permittivity spectra were fitted using Havriliak–Negami equation. By using least square fit method the dielectric parameters such as static dielectric constant ([Formula: see text]), dielectric constant at high frequency ([Formula: see text]), relaxation time [Formula: see text] (ps) and relaxation distribution parameter ([Formula: see text]) were extracted from complex permittivity spectra at 25[Formula: see text]C. The intramolecular interaction of different molecules has been discussed using the Kirkwood correlation factor, Bruggeman factor. The Kirkwood correlation factor ([Formula: see text]) and effective Kirkwood correlation factor ([Formula: see text]) indicate the dipole ordering of the binary mixtures.

Characterization of relaxation processes over static permittivity frequency regime and compliance of the Stokes-Einstein-Nernst relation in propylene carbonate

Complex dielectric permittivity, alternating current electrical conductivity, electric modulus and impedance spectra of propylene carbonate were investigated in the frequency range from 20Hz to 1MHz and temperatures from 278K to 328K. The values of static permittivity, Kirkwood correlation factor, ionic conductivity, electric double layers and conductivity relaxation times, and the conductivity and relaxation activation energies of the propylene carbonate were determined. The effects of ionic impurities on electrical conduction and low frequency relaxation processes in propylene carbonate were explored. It was found that the conductivity behaviour of ionic contaminants in neat liquid propylene carbonate fulfilled the Stokes-Einstein-Nernst relation for the ions movement in viscous media. These results confirm great significance in interpretation of ion-conduction mechanism in liquid and solid polymer electrolytes when propylene carbonate is used as solvent and plasticizer, respectively.

Dielectric Dispersion and Molecular Interaction in Polymer (PVA)-Surfactant (SDS) mixtures using picosecond time domain reflectometry

The interaction between polymers and surfactants molecules in aqueous medium interaction has significant changes in dielectric dispersion and offer ascent to the development of affiliation structures. The correlation of interaction alters the ordering and interfacial properties. The dielectric portrayal study on relaxation and molecular interaction of in ternary blend of polymer and the surfactant viz. polyvinyl alcohol (PVA) and sodium dodecyl sulphate (SDS) in aqueous solutions focused on various concentrations at 298K. The excess permittivity (εE), electrical conductivity (σ), free energy of activation (ΔF), dielectric relaxation (τ), Kirkwood correlation factor (geff) for relative concentrations of the ternary specimens considered. The hydrated micelles in PVA pivot as one unit in the viscous medium with critical changes in dielectric parameters by the blend constituents of SDS in the frequency range 10MHz to 30GHz. The estimations of geff acclimates relationship component of molecular interaction and parallel orientation of molecular ordering.

DIELECTRIC RELAXATION STUDY OF BINARY MIXTURES AT DIFFERENT TEMPERATURES

&lt;div class="Section1"&gt;&lt;p&gt;&lt;strong&gt;Objective: &lt;/strong&gt;The objective of this work is to study the intermolecular interaction and hydrogen bonding of the two binary mixtures at different temperatures which are determined from &lt;strong&gt;s&lt;/strong&gt;tatic dielectric constants and their excess properties.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;Dielectric measurements have been carry out using a sensor which is based on frequency domain reflectometry technique. The excess dielectric properties, Kirkwood correlation factor and Bruggeman factor of the binary mixtures have also been calculated and reported in this paper.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;The positive and negative behavior of excess dielectric permittivity and variation in linear relation in Bruggeman factor suggests the presence of intermolecular interaction in the binary mixtures. The angular Kirkwood correlation factor confirms the parallel and antiparallel orientation of the dipoles in the mixtures.&lt;/p&gt;&lt;p&gt;Conclusion: The static dielectric constant of binary systems increases with the addition of the volume fraction of water and decreases with increase in temperature. From excess properties, it is confirmed that there is an intermolecular interaction between the studied binary systems. Such study is useful in drug-receptor interaction.&lt;/p&gt;&lt;/div&gt;

Dielectric relaxation studies of binary mixture of β-picoline and methanol using time domain reflectometry at different temperatures

Complex permittivity spectra of binary mixtures of varying concentrations of [Formula: see text]-picoline and Methanol (MeOH) have been obtained using time domain reflectometry (TDR) technique over frequency range 10 MHz to 25 GHz at 283.15, 288.15, 293.15 and 298.15 K temperatures. The dielectric relaxation parameters namely static permittivity ([Formula: see text]), high frequency limit permittivity ([Formula: see text]) and the relaxation time ([Formula: see text]) were determined by fitting complex permittivity data to the single Debye/Cole-Davidson model. Complex nonlinear least square (CNLS) fitting procedure was carried out using LEVMW software. The excess permittivity ([Formula: see text]) and the excess inverse relaxation time (1/[Formula: see text] which contain information regarding molecular structure and interaction between polar–polar liquids were also determined. From the experimental data, parameters such as effective Kirkwood correlation factor (geff), Bruggeman factor (fB) and some thermo dynamical parameters have been calculated. Excess parameters were fitted to the Redlich–Kister polynomial equation. The values of static permittivity and relaxation time increase nonlinearly with increase in the mol–fraction of MeOH at all temperatures. The values of excess static permittivity ([Formula: see text]E) and the excess inverse relaxation time (1/[Formula: see text] are negative for the studied [Formula: see text]-picoline — MeOH system at all temperatures.