Compound 1 is yellow and its UV-vis absorption spectrum in the solid state is shown in Figure The consecutive 638 nm light irradiation (red light) restores the original yellow color of 1vis and the its UV-vis spectrum is identical with that of the pristine 1 (Figure , brown solid line). The photochromic switching can be repeated in several cycles with the sample changing color between yellow and blue with no apparent photodegradation (Figure , inset) -a feature promising from the point of view of photoswitching of the magnetic properties.