INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
Critical effects on attractive solutes in binary liquid mixtures close to their consolute point: a new experimental strategy
K. I. GUTKOWSKI; R. FERNANDEZ PRINI; PEDRO F. ARAMENDÍA; MARÍA LAURA JAPAS
JOURNAL OF PHYSICAL CHEMISTRY B
Año: 2011 vol. 115 p. 15303 - 15303
The effect of near-criticality upon the properties of dilute solutions of attractive solutes has been previously studied only using pure solvents close to the vapor-liquid critical point. The experimental difficulties that plague this thermodynamic region have obscured somewhat the interpretations of the results. Consequently the coupling of long-range critical fluctuations with short-range intermolecular interactions is still a matter of debate. We developed a new strategy consisting in studying the changes in the solvation shell of probe molecules dissolved in a binary solvent mixture close to its lower consolute critical point. The study is based on UV-Vis absorption and fluorescent emission measurements of the solvatochromic and thermochromic effects of two dyes, Reichardt´s dye and Nile Red, dissolved in mixtures of lutidine-water. The results show unambiguously the existence of a subtle change in the composition of the near critical solvent surrounding the probe molecules with respect to the bulk composition, thus we conclude that the coupling of long-range fluctuations with short-range interactions is now firmly established.