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Assembly of pyridine-2-aldoxime drug with cucurbit [6]uril (CB[6]) has been investigated by 1H-NMR and 2D-ROESY NMR, UV-Vis spectroscopy, FT-IR spectroscopy, surface tension and conductivity measurements in aqueous saline environment. The distinct cationic receptor feature and the cavity dimension of the CB[6] emphasize that the macro-cyclic host molecule remain as complex with the nerve stimulus drug molecule. The results obtained from surface tension and specific conductivity measurements suggest 1:1 inclusion complex formation between drug and CB[6]. The stability constant evaluated by UV-Vis spectroscopic approach is 2.21×105 M−1 at 298.15 K, which indicates that the complex is sufficiently stable at physiological temperature.

The electrolytic conductivity of the tetraalkylammonium iodides, R4NI (R = butyl to heptyl), has been studied in (0.00, 0.25, 0.50 and 0.75) mass fraction of o-toluidine (C7H9N) in n-hexanol (C6H14O) at T = 298.15 K. The limiting molar conductance Λ0, association constants KA and the co-sphere diameter R for ion-pair formation in 0.00 and 0.25 mass fraction of solvent mixture have been evaluated using the Fuoss-equation. However, the deviation of the conductometric curves (Λ versus c1/2) from linearity for the electrolytes at 0.50 and 0.75 mass fraction of o-toluidine (C7H9N) in n-hexanol (C6H14O) indicates triple ion formation, and therefore the corresponding conductance data have been analyzed by the Fuoss–Kraus theory of triple ions. The observed values of the molar conductivity are explained by the ion-pairs (M+ + X− ↔ MX) and triple-ions ( 2 M + + X - ↔ M 2 X + , M + + 2 X - ↔ MX 2 - ) formation. From the investigations, the following trend in conductance of the solvated salts has been observed: Download : Download full-size image

Densities, ρ, viscosities, η, speeds of sound, u and refractive indices, n D, were measured for the binary systems of cyclohexylamine with 1-butanol, 2-butanol, isobutanol and t-butanol at 298.15 K over the entire composition range. From the experimental results, the excess volume, V E, the deviations in relative viscosity, Δη, and synergic index, I S, are derived by the equation developed by Kalentunc-Gencer and Peleg [J. Texture Studies 17, 61 (1986)] and Howell [Elucidation of protein–protein interactions in gels and foams, in Proceedings of 7th International Conference Wales 1993, edited by G.O. Phillips, P.A. Williams and D.J. Wedlock (Oxford University Press, New York, 1994)], respectively. Isentropic compressibility, , and deviation in refractive indices, Δn D, were also calculated. The above functions show the deviations from the additivity law, which depend on the nature of the carbon chain of the alcohols.

The densities and viscosities of six ternary mixtures of the water, monoalkanols; 1-propanol, 2-propanol and monoalkanoic acids; formic acid, acetic acid and propionic acid are determined over the entire range of composition at 298.15, 308.15 and 318.15 K. From the experimental observations, the viscous synergy and synergy interaction index are derived from the equations developed by Kalentunc-Gencer, Peleg and Howell, respectively. The speeds of the sound of these ternary mixtures have been measured over the whole composition range at the same temperatures, and also the excess molar volumes, the isentropic compressibilities and excess isentropic compressibilities have been evaluated from the experimental data.

Apparent molar volumes, V φ, viscosities, η, and apparent isentropic compressibilities, K φ, of glycine, L-alanine, L-valine and L-leucine in 0.05, 0.10, 0.15 mol Kg−1 catechol solutions have been determined at 298.15 K by measuring the densities, viscosities and ultrasonic speed of the above solutions respectively. The standard partial molar volumes, , standard volumes of transfer, , standard partial isentropic compressibilities, , transfer compressibilities, , hydration number, N w , of the amino acids have been calculated for investigating the various interactions in the ternary solutions. The linear correlation of partial molar volume and viscosity B-coefficients with increasing number of carbon atoms in the alkyl chain have been used to explain the contribution of charged end group ( , COO−) and the ‒CH2 group to . The results have been interpreted in the light of solute-solvent interactions in the mixed ternary solutions.

The excess molar volumes, VE, and viscosity deviations, Δη, were calculated from the measured density and viscosity data over the whole composition range for the ternary systems of 1,3-dioxolane (DO), dichloromethane (DM) + methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), butyl acetate (BA) and isoamyl acetate (IA) at 298.15 K. From the experimental observations the speed of sounds and refractive indices of these ternary mixtures have been measured over the entire range of composition at the same temperature. Also the isentropic compressibility, deviation in isentropic compressibility and deviation in molar refraction have been evaluated. The excess or deviation properties were found to be either negative or positive depending on the molecular interactions and the nature of liquid mixtures.

Electrolytic conductivities, densities, viscosities, and refractive indices of some lithium halides (LiCl, LiBr, and LiI) have been studied in mass fraction (0.10, 0.20, and 0.30) of ethylene glycol monomethyl ether + methyl alcohol mixtures at 303.15 K. The limiting molar conductivities (Λ0), association constants (KA), and the distance of closest approach of the ion (R) have been evaluated using the Fuoss conductance equation (1978). The Walden product is obtained and discussed. The limiting apparent molar volumes (ϕV°), experimental slopes (SV*) derived from the Masson equation, and viscosity A and B coefficients using the Jones−Dole equation have been interpreted in terms of ion−ion and ion−solvent interactions, respectively.

The excess molar volumes (VE) and viscosity deviations (Δη) have been calculated from experimental density (ρ) and viscosity (η) data of the binary mixtures of 1,3-dioxolane (DO) with 2-methoxyethanol (ME), 2-ethoxyethanol (EE), 2-butoxyethanol (BE), 2-propylamine (PA), and cyclohexylamine (CA) measured over the entire range of composition at 298.15 K. Moreover, deviations in isentropic compressibility (ΔKS) and molar refraction (ΔR) have been calculated from ultrasonic speed of sounds (u) and refractive indices (nD) of the mixtures, respectively. The excess or deviation properties were fitted to the Redlich−Kister polynomial equation to derive the adjustable parameters (Ak) and corresponding standard deviations (σ).

The apparent molar volumes, ?V, and viscosity B-coefficients, B, for nicotinic acid (NA) and benzoic acid (BA) in mixed solvents containing 10, 20, 30 mass % of n-amyl alcohol (n-AmOH) or isoamyl alcohol (i-AmOH) in methanol and in pure methanol (MeOH) were determined from the solution density and viscosity measurements at 298.15 K as function of concentrations of NA and BA. These results were, in conjunction with the results obtained in pure methanol, used to deduce the partial molar volumes of transfer, 0 ??V , and viscosity B-coefficients of transfer, ?B, for NA and BA from methanol to different mixed methanol solvents, in order to rationalize various interactions in the ternary solutions. An increase in the transfer properties of NA and BA with increasing mass % of n-AmOH and i-AmOH in methanol was observed and explained by the effect of structural changes and preferential solvation. Also, the free energies of viscous flow, ? 0? 1 ? and ? 0? ?2 , per mole of solvent and solute, respectively, were calculated and analyzed on the basis of the transition state theory of relative viscosity.