Quantitative structure-activity relationships for phenyl triazolinones of protoporphyrinogen oxidase inhibitors: A density functional theory study

The equilibrium geometries, electronic structures, and electrostatic potentials of a series of substituted phenyl triazolinones of protoporphyrinogen oxidase (PPO) inhibitors have been investigated by using the density functional theory (DFT) method. The quantum chemical descriptors, highest occupied molecular orbital and lowest unoccupied molecular orbital energy gap (DeltaE), weighted electrophilic, and nucleophilic atomic frontier electron density (FA and FA), and net atomic charge (Q), were computed at the same DFT level. Based on these precise quantum chemical descriptors, a quantitative structure-activity relationships study has been carried out and shown that Q(C11), F-N5(E), F-C10(N), and DE of individual molecules are most likely to be responsible for the in vitro biological activity and greenhouse preemergence activity of phenyl triazolinones. The ability to quite accurately predict the biological activity of phenyl triazolinones by using DFT-based QSAR can be expected to help facilitate the design of additional substituted phenyl triazolinones as PPO inhibitors with good biological activity. (C) 2004 Wiley Periodicals, Inc.