Photoalignment and surface-relief-grating formation are efficiently combined in low-molecular-weight halogen-bonded complexes

It is demonstrated that halogen bonding can be used to construct low‐molecular‐weight supramolecular complexes with unique light‐responsive properties. In particular, halogen bonding drives the formation of a photoresponsive liquid‐crystalline complex between a non‐mesogenic halogen bond‐donor molecule incorporating an azo group, and a non‐mesogenic alkoxystilbazole moiety, acting as a halogen bond‐acceptor. Upon irradiation with polarized light, the complex exhibits a high degree of photoinduced anisotropy (order parameter of molecular alignment > 0.5). Moreover, efficient photoinduced surface‐relief‐grating (SRG) formation occurs upon irradiation with a light interference pattern, with a surface‐modulation depth 2.4 times the initial film thickness. This is the first report on a halogen‐bonded photoresponsive low‐molecular‐weight complex, which furthermore combines a high degree of photoalignment and extremely efficient SRG formation in a unique way. This study highlights the potential of halogen bonding as a new tool for the rational design of high‐performance photoresponsive suprastructures.