High-Resolution Photochemical Reaction Using Triplet-Sensitizer Probes

Hideki Miki,Akira Otomo^† and Shinro Mashiko
Kansai Advanced Research Center,
National Institute of Information & Communications Technology,
588-2 Iwaoka,Nishi-ku,Kobe 651-2401 Japan
^†Corresponding author.

ABSTRACT

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. In this work, we 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. We used a cone-shaped dendron molecule to avoid sensitizer self-quenching caused by the triplet energy migration within the probe surface. We then confirmed efficient site separation of the cone's focal point by measuring the absorption and fluorescent properties of the rhodamine Battached to the focal point. 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.