Adding Properties — Property-Weighted Functions

One of the most important improvements for a radial distribution function is the possibility to introduce chemical properties of atoms or entire molecules to describe physicochemical, physical, or biological properties of a chemical structure rather than just the three-dimensional structure. 

All of the RDF functions presented already can be calculated including properties p of the individual atoms. These properties can be inserted in a preexponential term as a product leading to the property-weighted RDF descriptor, sometimes called RDF code  

This method transforms the frequency dimension into a property-weighted frequency dimension. The selection of atomic properties determines the characterization of the atoms within an RDF descriptor. Particularly, the classification of molecules by a Kohonen network is influenced by a decision for an atomic property. We can distinguish between static and dynamic atom properties. 

---

All new descriptors, QSAR approaches and chemometric strategies proposed since 2000 have been included in this handbook. Several new topics such as biodescriptors, characteristic polynomial-based descriptors, property filters, scoring functions, and cell-based methods have been added. Other topics, such as substructure descriptors, autocorrelation descriptors, delocalization degree indices, weighted matrices, connectivity indices, and so on, have been completely rewritten. 

Copolymers of 2-acrylamide-2-methylpropyldimethylammonium chloride and sodium 2-acrylamide-2-methylpropanesulfonate (AMPDAC-SAMPS) were prepared and their dilute solution properties studied as a function of copolymer composition, temperature, time, pH and added low-molecular-weight electrolytes [39-42]. Equimolar copolymers display a minimal viscosity in pure water and a maximal one in concentrated salt solutions. As the copolymer compositions deviate from an equimolar, charge imbalances increase the hydrodynamic volume of the macromolecules. 

---