Structural characterization of the ternary solvent mixture methanol–acetonitrile–1‐propanol

Abstract

Refractive indices and ET values were measured for the ternary mixture methanol–acetonitrile–1‐propanol at 25.0 °C for 13 mole fractions, and also for the corresponding binary mixtures, methanol–1‐propanol, methanol–acetonitrile and 1‐propanol–acetonitrile, at 25.0 and 50.0 °C, at 10 different compositions. Solvent exchange equilibrium models were applied to the transition energy of the Dimroth–Reichardt ET(30) solvatochromic indicator in the binary systems and the Redlich–Kister polynomial was used to correlate excess ETN and nD values for the binary solvent mixtures data. The results allowed the analysis of synergetic behaviours, polarizability effects and preferential solvation trends both in the binary and in the ternary mixtures. Our results point towards the prevalence of specific solute–solvent–solvent interactions mainly due to hydrogen bonding by the hydroxylic components of the ternary mixture. Copyright © 2002 John Wiley & Sons, Ltd.

Photoreduction of 4,4‘-Bipyridine by Amines in Acetonitrile−Water Mixtures: Influence of H-Bonding on the Ion-Pair Structure and Dynamics

“…In this regard, the 44BPY vibrational frequency analyzed above (Figure 1) appears to be a good probe for evaluating the polarity of solvent mixtures as it is sensitive to both the specific and nonspecific solutesolvent interactions. As a confirmation, the behavior observed in Figure 1 for the 44BPY frequency is very similar to that reported 4 for the Dimroth-Reichardt polarity parameter, E T , calculated from the peak position of the absorption spectrum of the solvatochromic indicator betaine in binary mixtures of protic and aprotic solvents and fitted by a preferential solvation model 10 based on solvent-exchange equilibria. Comparable results were found for the solvatochromic probe coumarin 153 11,12 and 102 dyes.…”

“…In the present paper, we report an investigation of the photoreduction of 44BPY by DABCO and TEA in acetonitrile−water mixtures in order to better characterize the nature and dynamics of the triplet ion pair in the presence of water molecules in the solvent cage. Our results emphasize the determinant role of specific interaction and preferential solvation effects , on the ion pair formation and reactivity. A particular attention has been given to the reaction of protonation of the “super” photobase 44BPY -• (p K a >15) that arises in the presence of water within a hydrogen-bonded complex, 44BPY -• ···HO−H.…”

“…From 0% to 10% water, the frequency increases rapidly from 997 to 1005 cm -1 . This shift is attributable to the formation of hydrogen bonding 2 and denotes a phenomenon of preferential solvation 3,4 of 44BPY by water. The solute-solvent interaction is thus dominated by specific solvent hydrogen bond acidity interactions.…”

Nitro-Substituted 4-[(Phenylmethylene)imino]phenolates: Solvatochromism and Their Use as Solvatochromic Switches and as Probes for the Investigation of Preferential Solvation in Solvent Mixtures

“…In the research carried out applying solvatochromic probes to understand medium effects, much attention has been given to the chemistry of solvent mixtures. − The behavior of solutes in these systems is more complex than in pure solvents due to the fact that in many cases preferential solvation (PS) occurs, leading to a solute microenvironment having more of one solvent than the other, in comparison to the bulk composition. Therefore, this is a very important subject in terms of analyzing kinetic, spectroscopic, and equilibrium data in solution.…”

Modeling Preferential Solvation in Ternary Solvent Systems

“…It combines a straightforward mathematical approach and an easy interpretation of results and has been applied with success to describe the behavior of many solvatochromic dyes 4,[33][34][35][36][37][38][39] and also that of rate constants and even of pK a in binary mixtures. [40][41][42][43][44][45][46] In the scope of our work with binary and ternary solvent systems, 47 we came across the need to quantitatively describe solvent-solvent and solute-solvent interactions in these media. With this purpose, we have been using transition energies of Reichardt's E T (30) betaine dye in various solvents as probes to monitor those interactions at a molecular level, that is, in the cybotactic region of the dye.…”