Functionalization of zinc oxide nanorods with diarylethene-based photochromic compounds

Two diarylethene molecules functionalized with a carboxylic acid function were grafted onto the surface of zinc oxide nanorods. Photochromic studies based on electronic absorption spectroscopy in solution showed that the switching units operate in a bidirectional mode, allowing both ring closure and ring-opening processes to take place successively in photochemical sequences combining irradiations of the open species at 300 nm and the closed ones at 500 nm. Depending on the molecular structure, some losses were observed presumably due to photodegradation. Compound 2 containing a terminal phenyl unit provides a longer conjugation pathway, thus offering red-shifted electronic absorption and better photochemical stability.