Fully and partially fluorinated flavone derivatives.

In the crystal structures of the fully and partially fluorinated flavone derivatives 5,6,7,8-tetrafluoro-2-(2,3,4,5,6-pentafluorophenyl)-4H-1-benzopyran-4-one, C(15)HF(9)O(2), (I), and 5,6,7,8-tetrafluoro-2-phenyl-4H-1-benzopyran-4-one, C(15)H(6)F(4)O(2), (II), the pentafluorophenyl group and the pyranone moiety in (I) are twisted due to repulsion of the F substituents, and a CO(delta(-))...pi(delta(+)) intermolecular interaction is observed between the carbonyl O atom and the pentafluorophenyl group. In (II), on the other hand, the phenyl group and the pyranone moiety are almost coplanar, and arene-perfluoroarene interactions are observed in the head-to-tail intermolecular columnar stacking between the phenyl group and the tetrafluorophenylene moiety.