Photoreactivity of fluoroquinolones: nature of aryl cations generated in water.

The nature of stabilized aryl cations generated from photodehalogenations of fluoroquinolones in aqueous media has been studied by comparing the photophysical and photochemical behavior of lomefloxacin (LFX) and its N(4')-acetylated form (ALFX). Photoproduct studies, laser flash photolysis, and emission measurements have shown that this small peripheral modification produces important changes in the properties of the singlet aryl cations generated. Also, in basic medium, a new photodehalogenation pathway for 6,8-dihalogenated fluoroquinolones has been observed.