Photoswitchable DNA-Intercalators
Scientists from Bielefeld and Siegen University have developed a photochromic compound whose activity to intercalate into dsDNA (double-straind DNA) can be controlled by light. Intercalators and especially switchable ones are of high interest for controlling biochemical recognition processes. Potential applications are tremendous and research activity is strongly increasing in many laboratories around the world.
Beside a recognition part the key of these compounds consists of a photochromic unit (photoswitch) whose structure and electronic behaviour can be reversibly changed by light exposure. In this joint contribution an N-methylphenanthrolinium-annelated spirooxazine derivative was prepared. Upon irradiation at 350 nm the spirooxazine (SO) is transformed to the corresponding photomerocyanine (PM) that binds to DNA. After irradiation with visible light the spirooxazine, which exhibits no significant DNA-binding properties, is regained. The association of the active form of this photoswitch with DNA was examined by CD and absorption spectroscopy, fluorescent intercalator displacement and viscometric titration.

This discovery was published by the Royal Society of Chemistry:
H, Ihmels, J. Mattay, F. May, and L. Thomas, Organic & Biomolecular Chemistry, 2013, 11, 5184–5188. [10.1039/C3OB40930A]