In this age of cloud storage, few people are backing up data on CD-RWs. The technology to rewrite data on compact discs was made possible by phase-change materials altered by the light and heat of lasers, though this had a limit of 1,000 rewrites.

Now, scientists investigating photoswitching molecules, which change their properties when irradiated, have been finding possible applications for these materials, ranging from photopharmacology to data storage.

Osaka Metropolitan University Graduate School of Engineering student Shota Hamatani, Dr. Daichi Kitagawa, a lecturer, and Professor Seiya Kobatake synthesized aza-diarylethenes, which have nitrogen in place of carbon in a molecular structure similar to known photoswitching diarylethenes. The new aza-diarylethenes exhibited not only photoswitching but thermal switching as well.

They demonstrated that the new photoswitching molecules can be used as a rewritable recording medium, using light or heat to write, and erasing with light.

“Our findings are very useful for the development of switching molecules that can be reversibly altered not only by light but also by heat,” Dr. Kitagawa proclaimed. “They may also lead to the development of new functional materials.”

The findings were published in Angewandte Chemie International Edition.