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The synthesis of a novel photochromic dithienylethene-based polyurethane and its characterization by optical spectroscopy and scanning tunneling microscopy are presented. This linear polyurethane builds up perfect free-standing films suited for photonic applications. Moreover it may be extruded to long mechanically stable fibers. The photochromic reactions of the polyurethane, as being the electrocyclic ring-closure and ring-opening reactions of the dithienylethene unit in the polymer backbone, occur in a completely reversible and highly efficient fashion.

Photo-excited carminic acid and carminic acid-DNA complexes in a buffer solution at pH= 7 have been examined using a variety of spectroscopy techniques, that are in particular, the femtosecond resolved fluorescence up-conversion and transient absorption spectroscopy M -1 that is typical for anthracycline-DNA complexes.