Large-Scale Supramolecular Structure in Solutions of Low Molar Mass Compounds and Mixtures of Liquids. III. Correlation with Molecular Properties and Interactions

Abstract

The presence of a large-scale supramolecular structure is evidenced in a large variety of electrolyte solutions, nonelectrolyte solutions, and mixtures of liquids. This structure comprises submicron-sized domains with different solute concentration from that in the rest of solution. While the first paper of this series [J. Phys. Chem. B 2006, 110 (9), 4329-4338] dealt with a detailed characterization of the supramolecular structure and the second paper [J. Phys. Chem. B 2006, 110 (9), 4339-4345] dealt with the kinetics of the formation of this structure and its long-time stability, the present work contains a detailed classification of systems with respect to the capability of formation of the supramolecular organization. Around 100 different solute-solvent pairs were investigated in total, covering most common inorganic and organic electrolytes, nonionic solid compounds, and a large variety of liquids. The main experimental techniques used were static and dynamic light scattering, which are very effective techniques in observing and characterizing association. Light scattering data were complemented by osmotic pressure data obtained by vapor pressure osmometry, which reflects association on a different principle. The presence and intensity of the supramolecular domain organization was correlated with properties and interactions between constituent molecules and ions. The most plausible explanation of the observed effect of the large-scale supramolecular structure at this stage of our knowledge is that domains form due to directional attractive interactions between solute molecules via hydrogen bond bridges formed by one or several solvent molecules, which are themselves hydrogen bonded.

Possible Further Evidence for the Thixotropic Phenomenon of Water

“…The 100 nm mesoscale inhomogeneities are long-lived, with relatively slow kinetics of formation which was monitored on mixing the components. Visualization of such large-scale structures via nanoparticle tracking analysis (NTA), presented in Figure 1, may additionally confirm their previous LLS work [74][75][76]. In addition, good agreement between the size distributions obtained from LLS and NTA was obtained.…”

“…The features of EZ water, in our opinion, also play an important role in the development of the thixotropic phenomenon that could be further confirmed by large-scale inhomogeneities found in aqueous systems. Literature indicating large scale inhomogeneities in aqueous solutions is accumulating, with emphasis on static and dynamic laser light scattering (LLS) measurements [69][70][71][72][73][74][75][76][77][78][79][80]. A wide variety of other experimental techniques may confirm that in aqueous under-saturated strong electrolyte solutions, the ions are not homogeneously distributed [63,[81][82][83][84][85][86].…”

“…Sedlák [74][75][76] investigated systems of D-glucose, NaCl, Na 2 SO 3 , MgSO 4 , Al(NO 3 ) 3 , acetic acid, dimethyl sulfoxide, ethanol and benzene with double distilled and subsequently deionized (not degassed) water. LLS results show that the solutes were distributed inhomogeneously on large length scales.…”

Rattling the cage: Micro- to mesoscopic structure in liquids as simple as argon and as complicated as water

“…[18] It is widely thought that solutes -in particular charged solutes -can increase or reduce the extent of the structure of the solvent, and are classified in the Hofmeister series as kosmotropes (structure makers) and chaotropes (structure breakers), through their influence on viscosity, and on protein folding and unfolding. [19][20][21] Mesoscopic structure has been observed in aqueous solutions [22][23][24] as well as in mixtures [25] by a variety of techniques.…”

Functional Taxonomy of Bacterial Hyperstructures

“…Such fluxes could occur, for example, along the filaments within cytoskeletal and transertion hyperstructures. Whatever the validity of these or other hypotheses, water is the most abundant constituent of cells, and we should remain open to new developments (237,291).…”