Highly efficient photodimerization of olefins in a nanotemplate on HOPG by scanning tunneling microscopy

Efficient photochemical reactions on a surface are of great importance for their potential applications in optoelectronic devices. In this work, a highly efficient photodimerization reaction of an olefin cocrystal built from two trans-1,2-bis(4-pyridyl)ethylenes (4,4′-bpe) and two isophthalic acid molecules via N⋯H–O hydrogen bonds in between was achieved in a nanotemplate on a highly oriented pyrolytic graphite (HOPG) surface. 4,4′-Bpe molecules first undergo the trans–cis isomerization followed by [2+2] photodimerization in the nanotemplate on HOPG upon UV irradiation. The efficiency of the isomerization as well as the photodimerization in the presence of the nanotemplate is much higher than that in its absence. These results provide a facile way to achieve highly efficient photodimerization of olefins on a large scale on surfaces.