Modeling of supramolecular ordering in mixtures: Structure, dynamics and properties

Abstract

The results on modeling supramolecular ordering in molecular mixtures, selforganized by H-bonding and the unified description of their thermodynamic, dielectric, optic, and kinetic properties have been reviewed. The hierarchy of the models of supramolecular species mixtures in thermodynamics of non-ideal solutions has been analyzed. New models of polyvariable supramolecular species as regards structure and composition, taking into account the cooperativity on H-bonding, as well as the description of their structure, composition, electric (dipole moment) and optical (polarizability tensor) properties, are discussed. The interrelations between thermodynamic functions (Gibbs energy, enthalpy, entropy), dielectric (permittivity), optic (refractive index and its fluctuation derivatives, defining Rayleigh light scattering) and kinetic properties of mixtures and microscopic characteristics of supramolecular species are presented. The dynamic models for describing supramolecular reorganization, intermolecular transitions, and energy transfer during thermal molecular motion, as well as fluctuation and relaxation (acoustic, dielectric, optic) phenomena in liquids on the basis of thermodynamic models with internal variables of the different tensor dimension have been considered. Expressions for fluctuation and relaxation contributions for both equilibrium and kinetic properties of nonideal mixtures are obtained. Contributions to integral Rayleigh light scattering due to fluctuation of the scalar parameters have been established. The methods for obtaining both integral and differential parameters of aggregation have been developed. The applications as to individual liquids (alcohols, N-amides, etc.) as well to binary mixtures with directed attractional molecular forces like H-bonds and both negative (e.g. acetone-chloroform) and positive (e.g. hydrocarbon-alcohol, chloroform-alcohol, ketone-alcohol) deviations from ideal solution behaviour are presented. The data on the structure and thermodynamics (equilibrium constant, Gibbs energy, enthalpy, and entropy) of supramolecular aggregation due to H-bonding in liquids and mixtures were obtained. The supramolecular assemblies in molecular liquids, selforganized by H-bonding, consisting of tens Thus the different forms of supramolecular ordering, characterizing the multiformity of aggregates both to structure and composition, differently manifest the macroscopic properties of liquids and mixtures. It's clear from the data obtained, that in associated mixtures with their common parameters of the state there is formation of supramolecular aggregates, consisting of tens of molecules, due to attractional directed molecular interactions like H-bonding, here the distribution functions of the aggregates on the size are quite wide. This is the evidence on the long-range translational and orientational molecular correlations in mixtures containing labile supramolecular aggregates due to the selforganisation processes through H-bonding. These supramolecular aggregates of nanosizes play an important role in the physicochemical properties of liquid systems.