Photochromic behavior of diarylbenzene nanoparticles prepared by top-down and bottom-up approaches†
The use of photochromic molecules as active elements in aggregates is very important for developing advanced materials in the next generation. The nanoparticle is one of the aggregate forms and has been attracting much attention due to not only the ease of preparation but also the characteristic photoswitching properties. In this work, we fabricated nanoparticles composed of a photochromic diarylbenzene by both ball-milling and reprecipitation methods and investigated their photochromic behaviors. The nanoparticles made by the ball-milling method had crystallinity, while those made by the reprecipitation method were amorphous. Both nanoparticles exhibited reversible T-type photochromic behavior, but the kinetics of the thermal back reaction depended on the state of the nanoparticles. The results in this study provide a convenient and useful way to prepare nanoparticles with different thermal back reactivity from one molecule.