Site-separation control using dendron molecular probes
towards high-resolution photochemical reaction

Akira Otomo, Hideki Miki, Isao Aoki, Shinro Mashiko

We propose molecular-scale photochemical-reaction control using triplet|triplet (T|T) energy transfer from a donor molecule attached on a probe to an acceptor on an insulator surface. We used a cone-shaped dendron molecule to avoid sensitizer self-quenching caused by the triplet energy migration within the probe surface. We demonstrated effective control of distance between functional sites on a surface using cone-shaped dendrons. The generation-three dendrons provide enough distance between the functional sites on the probe to reduce singlet energy transfer and it should control triplet energy migration. We also studied the feasibility of photochemical reactions on a substrate surface using a triplet sensitizer probe. We observed an efficient T|T energy transfer from Michler's ketone on the substrate to an acceptor molecule, cinnamoyl group, on the other substrate facing it. Approximately a quarter of the cinnamoyl groups were dimerized by triplet sensitization.