Next, the thermal stability of the metastable Z isomer was scrutinized (Figure , for more details see the Supporting Information). After red-light-induced accumulation of the Z isomer its thermal conversion into the stable E isomer was monitored in benzene solution in the dark. Finally, we set out to provide an application for PAT 1 to showcase its utility for lightresponsive materials. For this purpose, PAT 1 was introduced into transparent polystyrene polymers to test whether photoisomerization is transferable to a solid matrix. To our delight PAT 1 retains its solution behavior and provides a viable photoresponse in the polymer with adjunct significant color changes (Figure ). Very strong color contrast allows writing in the material with red or orange light and erase with the reverse illumination color. Thus, spatially resolved NIR photoswitching is established with PAT 1, which is especially interesting in the context of optical memory, smart material, and light responsive solid state research areas.