Insight into solute-solute and solute-solvent interactions of l-proline in aqueous-D-xylose/L-arabinose solutions by using physicochemical methods at temperatures from 293.15 to 318.15 K

Exploring the effects of saccharides on the solvation behaviour of L-Citrulline in aqueous medium: Volumetric, transition state theory, transfer parameters and spectroscopic approach

This study examines the volumetric, viscometric and UV-vis characteristics of L-Citrulline in water and aqueous saccharides at atmospheric pressure across the whole concentration range and the absorber operating temperature range of 293.15 K -313.15 K. Density, partial molar volume, apparent molar isobaric expansion, Hepler's constant and hydration number were among the examined volumetric parameters, and viscosity coefficients, viscosity deviation and free energy for viscous flow activation were among the examined viscometric parameters. Stronger interactions between L-Citrulline and L-Arabinose were indicated by the increase in the transfer characteristics in the following order: L-Arabinose > D-xylose. A comparison of the taste behaviours of L-Citrulline in water and in an aqueous solution of saccharides has also been attempted. L-Citrulline interacts with all solvents in a significant way, as evidenced by the UV-visible spectra suggested by the shift in UV-visible absorption maxima that correspond with a rise in L-Citrulline content in the solvent systems chosen.

Can Jones-Dole's B-Coefficient be a Consistent Structure-Making/Breaking Marker? Rigorous Molecular-Based Analysis and Critical Assessment of Its Marker Uniqueness

We analyzed the consistency, or lack thereof, of the conjectured connection between the sign of Jones-Dole's B-coefficient, or its isobaric-temperature derivative, and the structure-making/breaking ability of a solute in a dilute solution. We sought to shed light on some crucial issues, including (i) whether Jones-Dole's B-coefficient contains any embedded microstructural information, (ii) whether we can either assign any definite foundation to the widely used assumption about the sign of the B-coefficient and its structure-making/breaking trend or provide a rational justification for its use as a structure-making/breaking marker, and (iii) whether we actually need Jones-Dole's B-coefficient and its isobaric-temperature derivative as markers for the interpretation of structure-making/breaking trends. Thus, we first addressed the fundamental (statistical mechanical) microscopic to (thermodynamic) macroscopic foundations of a rigorous approach to the structure-making/breaking ability of a solute, regardless of the type of solvent or nature of the solute-solvent intermolecular interaction asymmetries, and its exact relationships to the resulting solution thermodynamics. Then, we derived the required conditions for the signs of the B-coefficient and/or its isobaric-temperature derivative to describe either a structure-making or a structure-breaking event, according to the actual solute-induced perturbation of the solvent microstructure, and consequently, tested the rationale underlying the B-based conjectured structure-making/breaking markers. Moreover, we invoked a well-known transition-state (TS) interpretation of the B-coefficient to connect it explicitly to the derived molecular-based structure-making/breaking signature and to find under which TS conditions the signs of the B-coefficient and its temperature derivative could describe the actual solute-induced perturbation of the solvent microstructure. We illustrated the actual structure-making/breaking behavior for a series of aqueous solutes over a wide range of solute-solvent intermolecular interaction asymmetries and compared their behavior against that predicted by Jones-Dole's based markers. This comparison, supported by rigorous thermodynamic arguments, highlighted the lack of uniqueness (or one-to-one correspondence) in the response of the B-based markers to the solute-solvent intermolecular interaction asymmetry, and therefore, their inadequacy as structure-making/breaking descriptors. Finally, we discuss the findings and provide a cautionary outlook on the use of the viscosity-based structural markers.