A model for a general type of intermolecular interaction between a molecule and a liquid phase based on the theory of generalized charges

Abstract

The described study was conducted within the framework of the problem of modelling high performance chromatography methods. The study was aimed at explaining the aspects of the theory of intermolecular forces that are relevant to the description of the selectivity of the chromatographic stationary phases and, as a result, to the a priori calculation of the chromatographic retention. The article presents a brief overview of the theory of generalized charges and its applications for the description of interatomic bonds (a homopolar bond and a donor-acceptor bond) and intermolecular forces (ab initio Lennard-Jones potential). A hydrogen bond is described as an example of a hydride bond without electron exchange and the corresponding charge separation. Each aspect of the theory was tested in the experiments whose results are presented in the referenced works and, to some extend, in this article. According to the suggested model, the energy of the intermolecular forces is determined by three different types of values, describing non-polar, polar, and hydrogen bonds. Each force is represented by its molecular descriptor: a generalised charge, a dipole moment, and two particles, which reflect the ability of the molecule to be either a donor, or acceptor in a hydrogen bond, respectively. The theory of generalised chargers helped us to obtain “structure-feature” bonds for all the elements of the intermolecular interaction energy. In particular, the article describes the contribution of the hydrogen bond to the overall energy of intermolecular interaction as the product of the threshold value, which has quantum-mechanical nature, and the probability of correct arrangement of the interacting molecules. This probability is determined as the probability of the system of interacting molecules being confined to a narrow potential well and is described by the parameters of the molecular structure. The suggested model was successfully used for a prior assessment of the heat of vaporisation of water, spirits, and acids, which proves the effectiveness of the developed approach.