Preferential Solvation of a Hydrophobic Probe in Binary Mixtures Comprised of a Nonprotic and a Hydroxylic Solvent:  A View of Solute−Solvent and Solvent−Solvent Interactions

Abstract

The fluorescence of pyrene, a hydrophobic probe, was investigated in binary mixtures comprising a nonprotic [acetonitrile, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofurane (THF)] and a protic (water, methanol, ethanol, propan-2-ol, and butan-1-ol) solvent. The variation in I/III values, the intensity ratios between the first and third bands in vibronic fine structures of the emission spectra, along with the variation in the more polar component was studied for each binary mixture. A preferential solvation (PS) model was adapted from the literature and successfully applied to the experimental data. In the mixtures containing acetonitrile, pyrene is always preferentially solvated by the nonprotic component. However, the extent of PS by acetonitrile diminishes with a decrease in the polarity of the protic cosolvent. These results were explained by the fact that pyrene is a highly hydrophobic probe. Thus, a replacement of the more polar protic cosolvent for one which is more hydrophobic may lead to a comparatively stronger interaction of the probe with the cosolvent through hydrophobic interactions. Synergism was observed for binary mixtures comprising THF and the studied alcohols, for DMSO with water and methanol, and for DMF with water. Finally, D2O−DMF and D2O−DMSO mixtures were studied and compared with the corresponding H2O mixtures. It was verified that the extent of PS in both cases is diminished if water is replaced by deuterium oxide. All data were interpreted in terms of solute−solvent and solvent−solvent interactions.

Glucosan controlled biomineralization of SrCO3 complex nanostructures with superhydrophobicity and adsorption properties

“…DMF-H 2 O mixed solvents have aroused a lot of interest due to DMF being a polar (hydrophilic) aprotic solvent with high boiling point (152.8 C) and being practically unassociated. [29][30][31][32][33] Also DMF-H 2 O mixed solvents, forming H 2 O $DMF and H 2 O$(DMF) 2 via hydrogen bond interactions, can be used as a model to understand the biochemical system, due to DMF having a peptide bond structure. The peptide bond is quite strong and rigid.…”

1,3,6,8-Tetraethynylpyrene and 1,3,6,8-tetrakis (trimethylsilylethynyl) pyrene: Photophysical properties in homogeneous media

“…Pyrene and its derivatives are among the popular fluorescent probes used in the study of photophysical and photochemical processes in homogeneous media [1,2], micelles [1], polymers [3,4] and biological structural units such as vesicles and cells [5] employing the sensitivity of its spectral parameters such as change in vibrational structure (especially intensity ratios of first and third vibronic bands), quantum yield of fluorescence, excimer formation, fluorescence anisotropy [6], lifetime of fluorescence, external or internal quenching, etc, to the change of the environment [7]. A systematic experimental investigation on a series of polycyclic aromatic hydrocarbons (PAHs) [8,9,10,11,12,13,14,15,16,17,18] for a variation in selective vibronic bands with respect to solvent polarity show that the PAHs broadly fall in to three categories.…”

Functional group dependence of the acid catalyzed ring opening of biomass derived furan rings: an experimental and theoretical study

“…Addition of an organic co-solvent is known to cause changes in ion dissociation and substrate pK a values 36 as well as leading to preferential solvation. 37 The concentration of reactant water is also decreased, which may slow the reaction.…”