Diarylethene Self-Assembled Monolayers: Cocrystallization and Mixing-Induced Cooperativity Highlighted by Scanning Tunneling Microscopy at the Liquid/Solid Interface.

Stimulus control over 2D multicomponent molecular ordering on surfaces is a key technique for realizing advanced materials with stimuli-responsive surface properties. The formation of 2D molecular ordering along with photoisomerization was monitored by scanning tunneling microscopy at the octanoic acid/highly oriented pyrolytic graphite interface for a synthesized amide-containing diarylethene, which underwent photoisomerization between the open- and closed-ring isomers and also a side-reaction to give the annulated isomer. The nucleation (Kn) and elongation (Ke) equilibrium constants were determined by analysis of the concentration dependence of the surface coverage by using a cooperative model at the liquid/solid interface.