Influence of Imidazolium Ionic Liquids on the Interactions of Human Hemoglobin with DyCl₃, ErCl₃, and YbCl₃ in Aqueous Citric Acid at T = (298.15, 303.15, and 308.15) K and 0.1 MPa

Abstract

Density, sound velocity, viscosity, surface tension, and molar conductivity for DyCl 3 •6H 2 O, ErCl 3 •6H 2 O, and YbCl 3 •6H 2 O from (0.002 to 0.012) mol•kg −1 in aqueous solutions of (a) citric acid (0.005 mol•kg −1 ) (b) citric acid + human hemoglobin (1 g•kg −1 ) and (c) citric acid + human hemoglobin +1alkyl-3-methylimidazolium chloride (0.001 mol•kg −1 ) ([RMIMCl], R = ethyl, butyl, and hexyl) at T = (298.15, 303.15, and 308.15) K and 0.1 MPa are reported. Densities were used to calculate the apparent molar volumes. The viscosity data are analyzed and interpreted using the extended Jones−Dole equation for lanthanide chloride to calculate viscosity A-and B-coefficient values. The varying trends of the aforesaid physicochemical parameters have been interpreted in terms of the solute− solute and solute−solvent interactions. An attempt has been made to investigate the influence of ionic liquid alkyl chain length on the interacting activities of lanthanide chloride with citric acid and the critical role being played by human hemoglobin in decoding the dominance of hydrophilic−hydrophobic interactions. 1-Ethyl-3methylimidazolium chloride induced greater conformational changes in the human hemoglobin than 1-butyl-3methylimidazolium chloride and 1-hexyl-3-methylimidazolium chloride due to differences in alkyl chain length with different interacting capabilities.