Cucurbit[7]uril as a universal anchor for photoswitchable monolayers on gold

Abstract

Photoresponsive self-assembled monolayers (SAMs) were fabricated on gold surfaces using cucurbit[7]uril (CB[7])-based host–guest complexes. In this architecture, the macrocyclic CB[7] unit serves as a universal anchoring platform, with one portal binding to the gold surface and the opposite portal encapsulating a photoswitchable molecular rod featuring a pyridinium–adamantyl recognition site. Four distinct molecular rods were synthesized to demonstrate the versatility of this modular approach. In solution, all supramolecular complexes retained the inherent photoresponsive behavior of the parent rods, exhibiting reversible isomerization with high fatigue resistance and minimal perturbation from CB[7] complexation. Upon surface immobilization, the resulting monolayers retained functional photoactivity, as demonstrated on all four systems. These results underscore the potential of CB[7]-anchored assemblies for the fabrication of robust, light-responsive surfaces and molecular devices.