Modeling of ion complexation and extraction using substructural molecular fragments

A substructural molecular fragment (SMF) method has been developed to model the relationships between the structure of organic molecules and their the rmodynamic parameters of complexation or extraction. The method is based on the splitting of a molecule into fragments, and on calculations of their c ontributions to a given property. It uses two types of fragments: atom/bond sequence and "augmented atoms"(atoms with their nearest neighbors). The SM F approach is tested on physical properties of C-2-C-9 alkanes (boiling poi nt, molar volume, molar refraction, heat of vaporization, surface tension, melting point, critical temperature, and critical pressures) and on octanol /water partition coefficients. Then, it is applied to the assessment of (i) complexation stability constants of alkali cations with crown ethers and p hosphoryl-containing podands, and of beta-cyclodextrins with mono- and 1,4- disubstituted benzenes, and (ii) solvent extraction constants for the compl exes of uranyl cation by phosphoryl-containing ligands.