Surface-junction effects on interfacial electron transfer between bis(terpyridine)iron(II) and hydrogen-terminated silicon(111) electrode

Interfacial electron transfer at bis(tpy)-iron(II) complexes (tpy=2,2′:6′,2′′-terpyridine) on Si(111) electrodes was investigated by using four types of surface-anchor terpyridine ligands. Despite the greater distance, electron transfer between the bis(tpy)-iron(II) unit and the electrode is accelerated in surface-anchor ligands with an additional phenylene group. Anchor ligands: The electron-transfer rate constant (k _ET) for [Fe(tpy)₂] (tpy=2,2′:6′, 2′′-terpyridine) complexes linked by four types of anchor ligands on hydrogen-terminated Si(111) was investigated. The anchor ligands with phenylene units exhibited greater k_ET values in spite of their longer distance (see scheme).