Phenanthrene-bridged diarylethenes: Synthesis, photochromism and non-destructive readout

Here we report on the synthesis and photochromism of a group of newly designed phenanthrene-bridged diarylethenes. The structure of one diarylethene derivative was determined by single crystal X-ray diffraction analysis. The photochromic dyes cyclize smoothly in polar organic solvents and water upon UV light irradiation while undergo fading under visible light. These photochromic materials have non-destructive readout capability through fluorescent modulation. Fluorescent read-out lights of them are 390 and 385 nm respectively. The non-destructive read out capability of them was studied with density functional theory and the results indicated that the cyclization probably took place at the second rather than the first excited states.