Photoswitchable conductivity in a rigidly dendronized salt.

Light switch: a dendronized salt exhibiting photoswitchable conductivity was designed and synthesized. The salt consists of tetrabutylammonium cations and large, rigidly dendronized borate anions, each bearing eight photoresponsive azobenzene moieties. The conductivity of solutions of this salt can be reversibly switched by irradiation, owing to light-induced changes in the overall size of the dendronized anion and the density of its polyphenylene shell.