Dynamically Chiral Surfaces Using Photoresponsive Overcrowded Alkenes.

Combining surface chirality and photoresponsiveness can result in interfaces with dynamic stereochemical properties. Such materials offer unique opportunities in the context of tunable chiral recognition at interfaces. Here, we present a strategy to achieve dynamically chiral surfaces using self-assembled molecular networks (SAMNs) of overcrowded alkene-based molecular motors on highly oriented pyrolytic graphite. The chiroptical properties and the dynamic behavior of the molecular motors are maintained when confined in the SAMN, as shown using scanning tunneling microscopy (STM) with in situ irradiation. Light triggers the transition from a homochiral assembly of the stable state of a molecular motor (RP chirality) to the heterochiral coassembly between the stable and the metastable state (RP/RM chirality). The RP/RM coassembly is a kinetic phase that disappears once the external stimulus is removed─highlighting the reversibility of the system. These results demonstrate how molecular motion can be harnessed to encode reversible chirality into surfaces.