Milan Chandra Roy

Host–guest inclusion complexes of α and β-cyclodextrins with α-amino acids

Studies of molecular inclusions of a congener series of guest amino acid molecules into the host cavity of α and β-cyclodextrins in aqueous solution have been focused on modern research gaining far reaching effect. With both the α and β-cyclodextrins, it is found that 1 : 1 hosts–guest inclusion complexes are formed with all the guest molecules at both low and high pH. The variation of the thermodynamic parameters with guest size and state are used to draw inferences about contributions to the overall binding from the driving forces, viz., hydrophobic effect, van der Waals forces, H-bonds, electrostatic forces, structural effect and configurational theory. The formation and comparative study of inclusion complexes have been analyzed by available data supplemented with surface tension, pH, density, viscosity, and refractive index.

Investigation of an inclusion complex formed by ionic liquid and β-cyclodextrin through hydrophilic and hydrophobic interactions

An investigation of the inclusion behavior of a guest ionic liquid (IL) 1-methyl-3-octylimidazolium tetrafluoroborate into the host cavity of β-cyclodextrin in aqueous solution has been carried out towards modern research to gain a far reaching effect. Surface tension and conductivity measurements showed that a 1 : 1 host–guest inclusion complex was formed and is favourable in the above system. Density, viscosity and refractivity measurements were also employed to study the same. The limiting apparent molar volume, viscosity B-coefficient, and molar refraction data have been used to characterize the solute–solvent interactions between the IL and cyclodextrin in the experimental ternary solution system.

Study of ion-pair and triple-ion origination of an ionic liquid ([bmmim][BF4]) predominant in solvent systems

Electrolytic conductivities, densities, viscosities, and FT-IR spectra of 1-butyl-2,3 dimethylimidazolium tetrafluoroborate ([bmmim][BF4]) have been studied in tetrahydrofuran, dimethylacetamide and methyl cellosolve at different temperatures. The limiting molar conductivities, association constants, and the distance of closest approach of the ions have been evaluated using the Fuoss conductance equation (1978). The molar conductivities observed were explained by the formation of ion pairs and triple ion formation. Ion–solvent interactions have been interpreted in terms of apparent molar volumes and viscosity B-coefficients which are obtained from the results supplemented with densities and viscosities, respectively. The limiting apparent molar volumes, experimental slopes 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. However, the deviation of the conductometric curves (Λ vs. √c) from linearity in tetrahydrofuran indicated triple-ion formation and therefore corresponding conductance data have been analyzed by the Fuoss–Kraus theory of triple ions. The limiting ionic conductances have been estimated from the appropriate division of the limiting molar conductivity value of tetrabutylammonium tetraphenylborate as the “reference electrolyte” method along with a numerical evaluation of ion-pair and triple-ion formation constants (KP ≈ KA and KT). The FT-IR spectra for the solvents as well as the solute in solvents have also been studied. The results are discussed in terms of ion–dipole interactions, hydrogen bond formation, structural aspects, and configurational theory.

Study to explore diverse interactions of amino acids and vitamin molecule in aqueous environment

ABSTRACT Physico-chemical study of solute–solvent interactions in phenylalanine, histidine and aqueous solution of nicotinic acid (vitamin) has been investigated by thermophysical properties. The apparent molar volume (ϕ), viscosity B-coefficient and molal refraction (RM) of phenylalanine and histidine have been studied in 0.01, 0.03 and 0.05 mol dm−3 aqueous vitamin solutions at different temperatures. Using the density data, Masson equation has been employed to obtain the limiting apparent molar volumes (ϕ) and experimental slopes (), which deduced the solute–solvent and solute–solute interactions, respectively. Using the Jones–Dole equation, the viscosity data were examined to determine the viscosity A and B coefficient. The Lorentz–Lorenz equation has been employed to determine the molar refractions (RM). The overall results established the strong solute–solvent interactions between the studied amino acids and vitamin mixture in the ternary solutions. UV-visible absorption spectra of the ternary solutions also stand in support of the results obtained.