Abstract A novel diarylethene with a bipyridyl unit has been designed and synthesized for the first time. Its photochromic behaviors could be modulated by protonation and coordination with Cu (II). The absorption maximum of the closed-ring isomer shifted from 569 to 666 nm when trifluoroacetic acid was added. Furthermore, the closed-ring isomer behaved as a sensitive colorimetric sensor, exhibiting an open-ring reaction upon ...
