ELECTROTOPOLOGICAL STATE INDEXES FOR ATOM TYPES - A NOVEL COMBINATION OF ELECTRONIC, TOPOLOGICAL, AND VALENCE STATE INFORMATION

The electrotopological state formalism is developed further in conjunction with atom classification. The classification scheme is based on the characteristics of hydride groups: (1) atomic number of an atom as element identifier; (2) a valence state designation consisting of valence and simple connectivity delta values (for each atom together with its bonded hydrogen atoms, as in -CH3 or -NH-), and (3) an aromaticity indicator. This scheme may be viewed as a three-dimensional array. In a few cases, bonded neighbor analysis is also required. The scheme is developed and illustrated. For each atom type in a molecule, the electrotopological state indices are summed. These atom type E-state indices, based on a summation of E-state values, are useful for database characterization, molecular similarity analysis, and QSAR. A QSAR/QSPR example is given for boiling point for a set of 245 alkanes and alcohols for which the standard error is 8.0 degrees C.