A PM6 STUDY ON THE REACTIVITY OF OH GROUPS IN FISETIN: STRUCTURAL AND ELECTRONIC FEATURES OF ...
 
Z. S. Marković , J. M. Dimitrić Marković , Ć. Doličanin
 
Abstract
 
In the present study the fisetin molecule has been considered theoretically by performing semiempirical molecular orbital theory calculations in the gas phase. Preoptimization was performed by PCMODEL, version 7.0, that involved an MMX force field. The semiempirical Paramterization Method 6 (PM6) within the Unrestricted Hartree-Fock (UHF) formalism has been considered to fully optimize the geometries of the systems considered. The results of bond order, BDE, highest occupied molecular orbital (HOMO), and Mulliken spin density for fisetin were presented. The structure-activity relationship was examined in the light of these results. Particular attention was devoted to semiemirical interpretation of the reactivity of the OH groups in fisetin and the radicals formed after H-removal from this molecule. Keto-enol tautomerism before H-abstraction was also discussed for explaining the role of 3-OH group.