A novel PI index and its applications to QSPR/QSAR studies

A novel topological index, PI (Padmakar-Ivan index), is derived in this pap er. The index is very simple to calculate and has disseminating power simil ar to that of the Wiener (W) and the Szeged (Sz) indices. The comprehensive studies show that the proposed PI index correlates highly with W and Sz as well as with physicochemical properties and biological activities of a lar ge number of diversified and complex compounds. The proposed PI index promi ses to be a useful parameter in the QSPR/QSAR studies. The stability of eac h model is demonstrated by applying cross-validation test. Furthermore, mor e favorable comparison with other representative indices such as the Randic index is also made in order to establish the predictive ability of the PI index. The results have shown that in several cases the PI index gave bette r results.