Small-angle neutron scattering study of D<sub>2</sub>O–alcohol solutions

D’Arrigo, G.; Teixeira, J.

doi:10.1039/ft9908601503

Cited by 88 publications

(52 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1b) show coherent structure, with larger correlation lengths present in pyridine solutions, corresponding to clusters of tens to hundreds of molecules, while the small correlation length for the isopropanol implies aggregates of only a few molecules, as would be expected. The presence of structure in these solutions is consistent with previous SANS experiments 46-48. When 3 molal GdmCl is added to isopropanol (Fig.…”

Section: Resultssupporting

confidence: 91%

“…For this reason, it is not possible to determine simultaneously the exact composition of the clusters and the concentration of the clusters. This has been described previously by D’Arrigo and Teixeira,46 who showed that micelle-like clusters of solute in D 2 O or water-solute aggregates in the remaining water and solute monomers are the two most likely structures present in solution.…”

Section: Resultssupporting

confidence: 71%

See 1 more Smart Citation

Preferential Interactions of Guanidinum Ions with Aromatic Groups over Aliphatic Groups

et al. 2009

View full text Add to dashboard Cite

Small angle neutron scattering (SANS) and molecular dynamics (MD) simulations were used to characterize the long range structuring (aggregation) of aqueous solutions of isopropanol (IPA) and pyridine, and the effect on structuring of guanidinium chloride (GdmCl). These solutes serve as highly soluble analogs of the non-polar aliphatic (IPA), and aromatic (pyridine) side chains of proteins. SANS data showed that isopropanol and pyridine both form clusters in water resulting from interaction between non-polar groups of the solutes, with pyridine aggregation producing longer-range structuring than isopropanol in 3 molal solutions. Addition of GdmCl at 3 molal concentration considerably reduced pyridine aggregation, but had no effect on isopropanol aggregation. MD simulations of these solutions support the conclusion that long range structuring involves hydrophobic solute interactions, and that Gdm+ interacts with the planar pyridine group to suppress pyridine-pyridine interactions in solution. Hydrophobic interactions involving the aliphatic groups of isopropanol were unaffected by GdmCl, indicating that the planar and weakly hydrated Gdm+ cation cannot make productive interactions with the highly curved or “lumpy” aliphatic groups of this solute. These observations support the conclusion that the effects of Gdm+ ions on protein-stabilizing interactions involving aromatic amino acid side chains make significant contributions to the denaturant activity of GdmCl, whereas interactions with the “lumpy” aliphatic side chains are likely to be less important.

show abstract

Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 71%

Preferential Interactions of Guanidinum Ions with Aromatic Groups over Aliphatic Groups

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Subsequent DLS measurements in the temperature range 283 ≤ T/K ≤ 313 indicated that contamination in BE samples might have led to formation of such large diffusers, and for contaminationfree samples, the estimated correlation lengths were in general agreement with those from neutron 2-6 and light scattering measurements. 23 The scenario becomes even more complex with SANS measurements 5,6 reporting rapid growth of the correlation length with the solution temperature approaching T c . In addition, scaling laws related to critical phenomena appeared to explain the considerable slowing down of diffusivities in these mixtures as critical concentration (X BE c ) and temperature (T c ) were approached.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneity in (2-butoxyethanol + water) mixtures: Hydrophobicity-induced aggregation or criticality-driven concentration fluctuations?

Indra

Biswas

2015

The Journal of Chemical Physics

View full text Add to dashboard Cite

Micro-heterogeneity in aqueous solutions of 2-butoxyethanol (BE), a system with closed loop miscibility gap, has been explored via absorption and time-resolved fluorescence measurements of a dissolved dipolar solute, coumarin 153 (C153), in the water-rich region at various BE mole fractions (0 ≤ XBE ≤ 0.25) in the temperature range, 278 ≤ T/K ≤ 320. Evidences for both alcohol-induced H-bond strengthening and subsequent structural transition of H-bond network have been observed. Analyses of steady state and time-resolved spectroscopic data for these aqueous mixtures and comparisons with the results for aqueous solutions of ethanol and tertiary butanol indicate that alcohol aggregation in BE/water mixtures is driven by hydrophobic interaction with no or insignificant role for criticality-driven concentration fluctuations preceding phase separation. Excitation energy dependence of fluorescence emission of C153 confirms formation of aggregated structures at very low BE mole fractions. No asymptotic critical power law dependence for relaxation rates of the type, k ∝ (|T - Tc|/Tc)(γ), with γ denoting universal critical constant, has been observed for both solute's rotational relaxation and population relaxation rates in these mixtures upon either approaching to critical concentration or critical temperature. Estimated activation energies for rotational relaxation rate of C153 and solution viscosity have been found to follow each other with no abrupt changes in either of them at any mixture composition. In addition, measured C153 rotation times at various compositions and temperatures reflect near-hydrodynamic viscosity coupling through the dependence,〈τr〉∝ (η/T)(p), with p = 0.8-1.0, suggesting solute's orientational relaxation dynamics being, on an average, temporally homogeneous.

show abstract

“…Recently, molecular dynamics simulations have shown the presence of micelle-like fluctuations over a dilute concentration range, 3 mol % to 8 mol % (11 mass % to 26 mass %) TBA in water [7]. Numerous experimental studies and other simulations support this picture [14][15][16][17][18][19][20]. Micelle-like structural fluctuations lead to anomalies in the thermodynamic properties of TBA-water solutions [7].…”

Section: Introductionmentioning

confidence: 99%

Phase behavior and mesoscale solubilization in aqueous solutions of hydrotropes

Subramanian

Анисимов

2014

Fluid Phase Equilibria

View full text Add to dashboard Cite

Hydrotropes are amphiphilic molecules that are too small to spontaneously form equilibrium structures in aqueous solutions, but form dynamic, non-covalent assemblies, referred to as clusters. In the presence of a hydrophobic compound, these clusters seem to get stabilized leading to the formation of long-lived, highly stable mesoscopic droplets, a phenomenon that we call "mesoscale solubilization". In this work, we focus on the unusual mesoscopic properties of aqueous solutions of a nonionic hydrotrope, namely tertiary butyl alcohol (TBA), on addition of various hydrophobic compounds. Aqueous TBA solutions, in about 3 mol % to 8 mol % TBA concentration range and about 0 °C to 25 °C temperature range, show the presence of short-ranged (~ 0.5 nm), short-lived (tens of picoseconds) molecular clusters which result in anomalies of the thermodynamic properties. These clusters are transient but do not relax by diffusion, thus distinctly different from conventional concentration fluctuations. In this concentration and temperature range, upon the addition of a third (more hydrophobic) component to TBA-water solutions, long-lived mesoscopic droplets of about 100 nm size are observed. In this work, we clarify the ambiguity behind the definition of solubility and elucidate the phenomenon of mesoscale solubilization. A systematic study of the macroscopic and mesoscopic phase behavior of three ternary systems TBA-water-propylene oxide, TBA-water-isobutyl alcohol, and TBA-water-cyclohexane has been carried out. We differentiate between molecular solubility, mesoscale solubilization, and macroscopic phase separation. We have confirmed that practically stable aqueous colloids can be created from small molecules, without addition of surfactants or polymers. Such kind of novel materials may find applications in the design of various processes and products, ranging from pharmaceuticals to cosmetics and agrochemicals.

show abstract

Small-angle neutron scattering study of D₂O–alcohol solutions

Cited by 88 publications

References 25 publications

Preferential Interactions of Guanidinum Ions with Aromatic Groups over Aliphatic Groups

Preferential Interactions of Guanidinum Ions with Aromatic Groups over Aliphatic Groups

Heterogeneity in (2-butoxyethanol + water) mixtures: Hydrophobicity-induced aggregation or criticality-driven concentration fluctuations?

Phase behavior and mesoscale solubilization in aqueous solutions of hydrotropes

Contact Info

Product

Resources

About

Small-angle neutron scattering study of D2O–alcohol solutions

Cited by 88 publications

References 25 publications

Preferential Interactions of Guanidinum Ions with Aromatic Groups over Aliphatic Groups

Preferential Interactions of Guanidinum Ions with Aromatic Groups over Aliphatic Groups

Heterogeneity in (2-butoxyethanol + water) mixtures: Hydrophobicity-induced aggregation or criticality-driven concentration fluctuations?

Phase behavior and mesoscale solubilization in aqueous solutions of hydrotropes

Contact Info

Product

Resources

About

Small-angle neutron scattering study of D₂O–alcohol solutions