Host–guest inclusion complexes of β-cyclodextrin with two vitamins viz., nicotinic acid and ascorbic acid in aqueous medium have been explored by reliable spectroscopic, physicochemical and calorimetric methods as stabilizer, carrier and regulatory releaser of the guest molecules. Job’s plots have been drawn by UV-visible spectroscopy to confirm the 1:1 stoichiometry of the host-guest assembly. Stereo-chemical nature of the inclusion complexes has been explained by 2D NMR spectroscopy. Surface tension and conductivity studies further support the inclusion process. Association constants for the vitamin-β-CD inclusion complexes have been calculated by UV-visible spectroscopy using both Benesi–Hildebrand method and non-linear programme, while the thermodynamic parameters have been estimated with the help of van’t Hoff equation. Isothermal titration calorimetric studies have been performed to determine the stoichiometry, association constant and thermodynamic parameters with high accuracy. The outcomes reveal that there is a drop in ΔSo, which is overcome by higher negative value of ΔHo, making the overall inclusion process thermodynamically favorable. The association constant is found to be higher for ascorbic acid than that for nicotinic acid, which has been explained on the basis of their molecular structures.

Partial molar volumes (V 0 φ ) and viscosity B-coefficients of sodium molybdate in 1,3-dioxolane + water mixtures have been determined from solution density and viscosity measurements at 303.15, 313.15, and 323.15 K and at various electrolyte concentrations. Also, the adiabatic compressibility of different solutions has been determined from the measurement of sound speeds at 303.15 K. The experimental density data were evaluated by the Masson equation, and the derived parameters were interpreted in terms of ion-solvent and ion-ion interactions. The viscosity data have been analyzed using the Jones-Dole equation, and the derived parameters, B and A, have also been interpreted in terms of ion-solvent and ion-ion interactions, respectively. The structure-making or breaking capacity of the electrolyte under investigation has been discussed in terms of the sign of (δ 2 V 0 φ /δT 2 ) P . The compressibility data obtained from sound speeds of different solutions indicate the electrostriction of the solvent molecules around the ions.

The apparent molar volumes and viscosities of three alkali metal chlorides, namely, lithium chloride, sodium chloride, and potassium chloride, have been determined in a 40 mass % tetrahydrofuran + water mixture at 303, 308, 313, and 318 K. The limiting apparent molar volumes (V φ o ) and slopes (S v *) have been interpreted in terms of ion-solvent and ion-ion interactions, respectively. Structure-making/-breaking capacities of various electrolytes have been inferred from the sign of (d 2 V φ o /dT 2 ), dB/dT, and the B coefficient for all electolytes studied. The viscosity data have been analyzed using the Jones-Dole equation. The results show that the three electrolytes act as structure promoters in this solvent mixture.

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The innovative study reveals the formation of 1:1 hosts–guest inclusion complexes for all the titled α-amino acids in the hydrophobic cavity of both α and β-cyclodextrin. The thermodynamic parameters for inclusion were studied depending on size and state of the guest molecules to draw inferences about contributions to the overall binding.

Apparent molar volumes and viscosity B-coefficients of glycine, L-alanine, and L-valine in 0.05, 0.10, and 0.15 mol‚dm -3 aqueous tetramethylammonium iodide (TMAI) solutions have been determined at 298.15 K from density and viscosity measurements. The standard partial molar volumes, standard volumes of transfer, and hydration number of the amino acids have been calculated for rationalizing various interactions in the ternary solutions. It has been found that the partial molar volume and viscosity B-coefficient varies linearly with the number of carbon atoms in the alkyl chain of the amino acids, and they were split into contributions from charged end groups (NH 3 + , COO -) and the CH 2group of amino acids. Furthermore, the side chain contribution to the partial molar volume and viscosity B-coefficient of the amino acids has been determined using a group additivity approach. The results have been discussed in terms of ion-dipolar, hydrophobic-hydrophobic, and hydrophilic-hydrophobic group interactions.

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Spectroscopic and physicochemical studies reveal formation of host–guest inclusion complexes of RNA nucleosides inside hydrophobic cavity of α and β-cyclodextrins.