Two-dimensional (2D) self-assembly of two 1,3,2-dioxaborine derivatives was investigated by STM. The molecules consist of π system and steric end groups. A droplet of toluene solution containing the molecules was deposited onto HOPG for preparing the assemblies. STM images showed that the mo- lecular structures affect the assembly structure. The dipole-dipole interaction and steric repulsion played important roles in the formation of the self-assembled monolayers.
Light-induced structural transformation of 4-(amyloxy)cinnamic acid (AOCA) on the surface of highly oriented pyrolytic graphite (HOPG) was investigated with scanning tunneling microscopy (STM). AOCA molecules form highly-ordered adlayer on HOPG spontaneously, stabilized by hydrogen bonding between neighboring molecules. After UV-light irradiation onto the adlayer, the ordered ad- layer was disrupted and a new disordered structure was observed, which indicated that dimerization of AOCA molecules took place. The STM results reveal the direct evidence for the photoisomerization of cin- namic acid at atom level.
