Structural Information and a Flexibility Index from the Molecular Connectivity 3χp Index
Lemont B. Kier, Lowell H. Hall · Quantitative Structure-Activity Relationships · 1983
Abstract The molecular connectivity 3χp index has been evaluated for its structure information content. This index has been found to relate closely to a quantitation of the number of gauche‐trans rearrangements possible in the molecule. The count of the number of three‐path fragments, 3Np carries similar information. Both indexes are shown to relate closely to density and to the Mann estimate of the average number of gauche arrangements in a molecule, Zg. The 3χp and 3NP indexes are superior to the Zg index in relating to alkane density. On the basis of the quantitation of gauche‐trans folding a flexibility index, F = n/1 ‐ 3NP has been empirically derived to rank alkanes according to a perception of their kinetic flexibility.