Orthogonal Photoswitching in Nematic Liquid Crystals.

Photoresponsive materials capable of orthogonal and path-independent switching are crucial for developing adaptive materials and smart technologies. In this work, we showcase a dual light-responsive nematic liquid crystalline system based on peri-anthracenethioindigo (PAT) and arylazopyrazole (AAP) doped into the liquid crystal 4-cyano-4'-pentylbiphenyl (5CB). The co-assembled supramolecular material exhibits a reversible phase transition between the nematic liquid crystalline and isotropic liquid state upon irradiation with different wavelengths of light ranging from ultraviolet to near infrared. These transformations are clearly visible using polarized optical microscopy, displaying either bright birefringent or completely dark images depending on the phase state. A key feature of this system is its ability to achieve independent and highly efficient photoisomerization of both photoswitches, ensuring orthogonality and path independence in solution as well as in the liquid crystalline phase. This orthogonal switching capability enables precise and reversible modulation of material properties, allowing sequential interconversion between multiple distinct states. Such a system represents an important proof-of-concept for future multifunctional materials that leverage light as a noninvasive external stimulus.