Photoswitchable DNA-binding properties of a photochromic spirooxazine derivative

Abstract

An N-methylphenanthrolinium-annelated spirooxazine derivative 2^SO whose DNA-intercalating properties are reversibly changed by a photochromic reaction was prepared. Upon irradiation at 350 nm the spirooxazine is transformed to the corresponding photomerocyanine 2^PM that binds to DNA. After irradiation with visible light the spirooxazine 2^SO, which exhibits no significant DNA-binding properties, is regained. The association of 2^PM with DNA was examined by CD and absorption spectroscopy, fluorescent intercalator displacement and viscometric titration.