Resolution of Microscopic Protonation Mechanisms in Polyprotic Molecules

Abstract

Microscopic ionization equilibria can be fully resolved by means of a novel site-binding model, which is based on a cluster expansion technique borrowed from statistical mechanics. This model permits a parameterization of the problem, and offers substantial advantages over the commonly used microscopic equilibrium constants. While the number of microconstants grows very rapidly with the size of the molecules, the necessary number of parameters of the site-binding model remain small, and one can even obtain common sets of such parameters within a homologous series of molecules. Based on this approach, two methods to obtain such microconstants are discussed, namely based on NMR titration data, and on the analysis of potentiometric titrations within a homologous series.