Well‐Defined Pillararene‐Based Azobenzene Liquid Crystalline Photoresponsive Materials and Their Thin Films with Photomodulated Surfaces

Photoresponsive materials (PRMs) have long been a hot topic and photomodulated smart surface is very appealing. Particularly, liquid crystalline PRMs are able to amplify and stabilize photoinduced orientation thanks to their self-assembling and ordering characteristics. Herein, the fi rst pillararene-based azobenzene liquid crystalline PRM with well-defi ned structure is presented, which can avoid the usually ill-defi ned composition drawback of polymer PRMs and prevent the severe H-aggregation from suppressing or even completely blocking photoresponse in simple azobenzene derivatives. The pillar[5]arene-based macrocyclic azobenzenes with variant length spacers show wide temperature range smectic liquid crystalline mesophases and excellent fi lm-formation property. The tubular pillar[5]arene macrocyclic framework provides suffi cient free volume for azobenzene moieties to achieve reversible photoisomerization and photoalignment; thus, their thin fi lms demonstrate excellent light-triggered modulation of surface free energy, wettability, and even photoalignment-mediated orientation of an upper layer discotic liquid crystal columnar mesophase. Such pillararene-based azobenzene liquid crystals represent novel and promising PRMs with extensive fascinating applications.