The self-sorting process triggered by photoreduction can be monitored by fluorescence microscopy, as shown in Fig. and Supplementary Movie S2. After approximately one minute of irradiation, a bundle of fibers is generated only in the irradiated spot (Fig. ), allowing for the creation of patterns. For instance, a circle can be drawn on a thin layer of a 2.6*10 -2 M solution of complex 2, deposited between two quartz plates, using a deuterium lamp equipped with a beam-shaping mask (Fig. ).