Self-Propelled Motion of a Coumarin Disk Characteristically Changed in Couple with Hydrolysis on an Aqueous Phase.

In this study, a coumarin disk was examined as a simple self-propelled object under a chemical reaction. A coumarin disk placed on an aqueous phase containing NaPO as a base exhibited continuous and oscillatory motion at lower and higher initial concentrations of NaPO, [NaPO], respectively. In addition, the period of the oscillation between rest and motion increased with increasing [NaPO].

Self-Propelled Motion of a Camphor Disk on a Photosensitive Amphiphilic Molecular Layer.

We have studied the self-propelled motion of a camphor disk on a 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole ( o-Cl-HABI) molecular layer, which was developed on water, as a photomechanical sensing system. The o-Cl-HABI dimer changed to its monomeric form upon UV light irradiation, and as a result, the surface pressure of the o-Cl-HABI molecular layer decreased. The reciprocating motion of a camphor disk in the absence of UV light irradiation was observed at A = 45 Å molecule, of which the surface pressure was ∼10 mN m.